DOE-HDBK-1122-2009 Chg Notice 2, Radiological Control Technician Training (Part 6 of 9)
Functional areas: Radiological Control Technician, Training, Radiation
This Handbook describes an implementation process for core training as recommended in chapter 14 to Implementation Guide G441.1-1C , Radiation Protection Programs for Use with Title 10, Code of Federal Regulations, Part 835, Occupational Radiation Protection, and as outlined in the DOE standard, Radiological Control (RCS). The Handbook is meant to assist those individuals within the Department of Energy, Managing and Operating contractors, and Managing and Integrating contractors identified as having responsibility for implementing core training recommended by the RCS
Related To:
Version history and related documents
Related documents
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 1 of 9, links to all Parts)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 2 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 3 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 4 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 5 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 7 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 8 of 9)
- DOE-HDBK-1122-2009 Chg Notice 2Radiological Control Technician Training (Part 9 of 9)
Document text
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Section 1
Part 6 of 9
Radiological Control Technician Training
Site Academic Training Study Guide Phase I
Coordinated and Conducted
for the
Office of Health, Safety and Security
U.S. Department of Energy
DOE-HDBK-1122-2009
Radiological Control Technician Study Guide
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Table of Contents
Page
Module 2.01 Radiological Documentation ............................................................................. 2.01-1
Module 2.02 Communication Systems ................................................................................... 2.02-1
Module 2.03 Counting Errors and Statistics ........................................................................... 2.03-1
Module 2.04 Dosimetry .......................................................................................................... 2.04-1
Module 2.05 Contamination Control ...................................................................................... 2.05-1
Module 2.06 Airborne Sampling Program/Methods .............................................................. 2.06-1
Module 2.07 Respiratory Protection ....................................................................................... 2.07-1
Module 2.08 Radiological Source Control ............................................................................. 2.08-1
Module 2.09 Environmental Monitoring ................................................................................ 2.09-1
Module 2.10 Access Control and Work Area Setup............................................................... 2.10-1
Module 2.11 Radiological Work Coverage ............................................................................ 2.11-1
Module 2.12 Shipment and Receipt of Radioactive Material................................................. 2.12-1
Module 2.13 Radiological Incidents and Emergencies........................................................... 2.13-1
Module 2.14 Personnel Decontamination............................................................................... 2.14-1
Module 2.15 Radiological Considerations for First Aid......................................................... 2.15-1
Module 2.16 Radiation Survey Instrumentation..................................................................... 2.16-1
Module 2.17 Contamination Monitoring Instrumentation...................................................... 2.17-1
Module 2.18 Air Sampling Equipment................................................................................... 2.18-1
Module 2.19 Counting Room Equipment............................................................................... 2.19-1
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DOE-HDBK-1122-2009
Module 2.01 Radiological Documentation Study Guide
2.01-1
Course Title: Radiological Control Technician
Module Title: Radiological Documentation
Module Number: 2.01
Objectives:
→ 2.01.01 List the types of records/reports that the Radiological Control group is
responsible for maintaining at your site.
Section 2
→ 2.01.02 Describe the types of records and reports used at your site by the
Radiological Control Group, to include but should not be limited to:
a. Radiological Work Permits
b. Survey Reports
c. Analysis Reports
d. Radiological Deficiency Reports
e. ALARA Documentation
f. Exposure Reports
→ 2.01.03 Explain the requirements for the records management system, such as
QC, auditability/retrievability, management information at your site.
INTRODUCTION
10 CFR 835 establishes radiation protection standards, limits, and program
requirements for protecting individuals from ionizing radiation resulting from the
conduct of DOE activities. It is important to maintain the proper documentation
to ensure that these standards and requirements are being met. An RCT plays a
vital role in supporting these requirements through proper documentation.
PURPOSE AND REQUIREMENTS
Radiological control records are needed to demonstrate the effectiveness of the
overall Radiation Protection program at DOE facilities. The records are used to
document radiological safety afforded to personnel on-site. Radiological control
records become valuable tools in work planning, evaluating past trends, and
guiding future performance goals. These records may become the basis for public
disclosures, legal proceedings, medical assessment and audits to show compliance
with company, state or federal requirements. Because of this, it is important that
these records be of high quality, readily retrievable, and managed for the
prescribed retention period. It is suggested that these records be cross-referenced,
when applicable, to aid in their retrieval.
DOE-HDBK-1122-2009
Module 2.01 Radiological Documentation Study Guide
2.01-2
References:
1. 10 CFR Part 835 (2007) "Occupational Radiation Protection.
2. "U.S. Department of Energy Radiological Control Standard"(2008).
RADIOLOGICAL RECORDS MANAGEMENT PROGRAM
Each DOE site must have a radiological records management program to ensure
that auditable records and reports are controlled through the stages of creation,
distribution, use, arrangement, storage, retrieval, media conversion and
disposition. The radiological records management program should include the
following:
a. Radiological Policy Statements
b. Radiological Control Procedures
c. Individual Radiological Doses
d. Internal and External Dosimetry Policies and Procedures (including Bases
Documents)
e. Personnel Training (course records and individual records)
f. ALARA Records
g. Radiological Instrumentation Test, Repair and Calibration Records
h. Radiological Surveys
i. Area Monitoring Dosimetry Results
j. Radiological Work Permits
k. Radiological Performance Indicators and Assessments
l. Radiological Safety Analysis and Evaluation Reports
m. Quality Assurance Records
n. Radiological Incident and Occurrence Reports (and Critique Reports, if
applicable)
o. Accountability records for sealed radioactive sources
p. Records for release of material to Controlled Areas
q. Reports of loss of radioactive material.
(Insert site specific information here.)
RADIOLOGICAL RECORD KEEPING STANDARDS
2.01.01 List the types of records/reports that the Radiological Control group is responsible
for maintaining at your site.
DOE-HDBK-1122-2009
Module 2.01 Radiological Documentation Study Guide
2.01-3
Section 3
Record keeping standards have been set by the Department of Energy. In addition
to the requirement of being accurate and legible, all radiological records must
include the following:
• identification of the facility, specific location, function, and process
• signature or other identifying code of the preparer and date
• legible entries in black ink
• corrections identified by a single line-out, initialed, and dated
• supervisory signature to indicate review and proper completion of the
forms.
Each radiological control organization should maintain a file of names, signatures
and initials for future identification of the person who signed or initialed a record.
In addition, radiological control records should not include:
• records that are corrected using opaque substances
• records that contain shorthand or other nonstandardized terms.
TYPES OF RADIOLOGICAL RECORDS
Various types of records are included in the radiological records management
program. These records fall into the following categories:
Employment History Records
Records detailing an employee's previous and on-going radiological work
assignments, yearly doses at DOE and non-DOE facilities must be maintained.
Where practical, the association between the radiation dose and job function must
be preserved for trend analyses and future worker health studies.
Personnel Radiological Records
Occupational Radiation Dose Records must be maintained for all contractor,
subcontractor, and Federal employees who are part of the personnel dosimetry
program. These records include results of personnel extremity, skin, eye and
whole body external dose measurements. The records also contain internal dose
information, including in vivo measurements, urine, fecal and other specimen
analysis and dose assessments. A complete record of radiological incidents and
occurrences involving personnel dose must also be retained. The investigation
and counseling of personnel radiological concerns must also be documented and
maintained within the radiological control record management program.
DOE-HDBK-1122-2009
Module 2.01 Radiological Documentation Study Guide
2.01-4
Medical Records
Reports of periodic medical examinations and evaluations, respirator fit-testing
results and records of medical treatment performed in support of the radiological
control program should be maintained. Sites are encouraged to maintain
nonoccupational radiation doses, such as therapeutic or large amounts of
diagnostic radiation doses for employees.
Radiological Training and Qualification Records
Records of training and qualification in radiological control are permanently
maintained to demonstrate that a person received appropriate information to
perform the work assignment in a safe manner. Qualification standard records are
retained for on-the-job, practical and formal classroom training. Training and
qualification records are available to first-line supervision and management to aid
in making work assignments. Included in the training records maintained, are
quizzes, tests, responses and acknowledgements of training, with the date and
signature of the person trained.
Instrumentation and Calibration Records
Section 4
Records of calibration, modification or maintenance, and periodic operational
checks of fixed, portable, and laboratory radiation measuring equipment must be
maintained. These records include frequencies, method, dates, personnel, training
and traceability of calibration sources. Records of additional tests and checks of
instrumentation used in conjunction with a suspected overexposure, questionable
indication, or unusual occurrence are also be retained.
Radiological Control Procedures
Sites should maintain radiological control procedures, policies, ALARA records,
work procedures, Radiological Problem Reports, Radiation Work Permits, and
supporting data as part of their radiological control record management program.
Specific requirements for each of these documents can be found in the DOE RCS.
2.01.02 Describe the types of records and reports used at your facility by the Radiological
Control group, to include but should not be limited to:
a. Radiological Work Permits
b. Survey Reports
c. Analysis Reports
d. Radiological Deficiency Reports
e. ALARA Documentation
f. Exposure Reports:
DOE-HDBK-1122-2009
Module 2.01 Radiological Documentation Study Guide
2.01-5
(Insert site specific information here.)
RECORDS MANAGEMENT
All records are required to be stored in a manner that ensures that they can be retrieved,
in addition to being able to maintain their integrity and security. Once a record has been
created, reviewed, and signed by appropriate supervision, the record should be considered
complete and must not be modified. Subsequent errors identified in a completed record
should be corrected by creating a supplemental record that includes traceability for the
correction. Radiological Control records should be protected from temperature extremes,
moisture, infestation, electromagnetic fields, excessive light, stacking, theft, and
vandalism. Protective measures should include vaults, file rooms with fixed fire
suppression, fire-rated cabinets, duplicate storage, or a combination of these.
(Insert site specific information here.)
RADIOLOGICAL REPORTING
All personnel that are monitored by a personnel dosimetry program shall be
provided an annual report of their radiation exposure. A person may also receive
a current radiation dose record upon special request. Terminating employees will
be given an exposure report within 90 days of their last day of employment
summarizing their radiation dose for the total period of employment at the
reporting facility.
2.01.03 Explain the requirements for the records management system, such as QC,
auditability/retrievability, management information at your facility.
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-1
Course Title: Radiological Control Technician
Module Title: Communication Systems
Module Number: 2.02
Objectives :
2.02.01 Explain the importance of good communication.
2.02.02 Identify two methods of communication and be able to determine
different types of each.
2.02.03 Describe different types of communication systems.
2.02.04 Describe the FCC and DOE guidelines regarding proper use of
communication systems.
2.02.05 Describe general attributes of good communications.
2.02.06 Explain the importance of knowing how to contact key personnel.
→ 2.02.07 Identify the communication systems available at your site and methods
Section 5
available to contact key personnel.
→ 2.02.08 Describe the emergency communication systems available at your site.
References:
(Add any site-specific references.)
IMPORTANCE OF COMMUNICATION
Good communication is important in everyday life to make sure our message is
clear, understood, and received. A clear concise communication eliminates
confusion and the possibility of misunderstanding. It is important that the
receiver understand the communication without unnecessary interpretation or
guess work. For a communication to be completed there must be a receiver. The
receiver is the person or group that the communication is intended. For a good
communication process there must be a clear concise message, a medium of
transmission (i.e. telephone, telegraph, E-mail, letter, signal flag, etc.), and a
receiver. If a response is required by the receiver, this can serve as confirmation
of reception of the communication, however, a response alone does not indicate
the communication was understood correctly. Misunderstanding of
2.02.01 Explain the importance of good communication.c. Energy
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-2
communication can potentially cause personal as well as physical damage to
equipment and surroundings.
In all communication processes, a sender of the communication must not assume
knowledge that is needed for safe execution of the desired response. The
communication must contain all pertinent information. Assuming or hoping the
receiver has a given understanding of a process can lead to an unsafe condition.
This is especially true in emergency situations that require immediate action or
response. Make sure in all communications that desired responses are not outside
the abilities or scope of the individual or group.
METHODS OF COMMUNICATION
In today's atmosphere of technology, there are methods of communications that
seemed unlikely just 20 years ago. Who would have thought that a car phone
would be as common as a home telephone. In general, communication can be
broken into two groups, verbal and nonverbal.
Verbal methods of communication include talking directly to another person,
telephone conversation, voice mail, video tele-conferencing, and various other
available mediums. Verbal methods generally allow discussion of details
followed by questions and/or an immediate response. Verbal communication
allows flexibility in the message along with added information without too much
difficulty in transmission.
Nonverbal methods of communication include signs, letters, signals, gestures,
documents, E-mail, and various other available mediums. Nonverbal methods
can limit the amount of information transmitted due to the difficulty in the
transmission method.
COMMUNICATION SYSTEMS
There are several communication systems available at most DOE sites. These may
include public address system, telephones, two-way radio, pagers, computer mail
system, and computer based bulletin boards. Following is a brief generic
description of each of these communication systems. The description is not
meant to be all inclusive, but a cursory overview of key aspects of each system.
2.02.02 Identify the two methods of communication and be able to determine different
types of each.
2.02.03 Describe different types of communication systems.
DOE-HDBK-1122-2009
Section 6
Module 2.02 Communications Systems Study Guide
2.02-3
Public Address
The public address system consists of loud speakers and calling stations located
throughout an area to provide audible notification to all personnel within the area.
The public address system may be used for routine messages, contacting groups
or individuals, items of interest to the general population, and emergency
notifications or warnings. The public address system should be administratively
controlled to ensure effectiveness in contacting facility personnel and availability
during emergency conditions.
Telephones
Telephones provide a means for point to point communication. The telephone
may be considered semiprivate when compared to the public address system,
however while on a DOE facility, all calls are subject to monitoring for security
reasons. The telephone system may offer the ability to leave a voice message
whenever the receiving party is unavailable. The telephone system provides
communication, but is subject to usage by other individuals which may impede
your contacting the person or persons needed in an emergency situation.
Two-way Radio
Two-way radio communication provides a direct link to other individuals on your
frequency or net. Although "traffic" on the radio may impair your message from
being clearly understood, usage is controlled by possession of a radio with the
correct frequency. Radio communication is subject to interference by outside
sources, which may garble or mask the message. This may be of significance
during emergency situations when location or type of emergency in progress must
be relayed to response teams. Two-way radios do provide mobility and access
while at remote locations.
Pagers
Pagers a small electronic devices capable of receiving signals from the telephone
system to alert the carrier of intended communication from another party. Pagers
provide access to personnel while away from the work location. Most pagers
provide only a voice message or phone number to contact. Pagers normally do
not allow the carrier to respond directly to the page verbally. Pagers provide a
means of contacting personnel when there whereabouts are unknown, but are
assumed to be within the site boundaries or very nearby.
Computer Mail Systems
Computer mail systems provide communication between computer terminals.
Most systems are linked via a local area network. This links enables users to
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-4
contact individuals or groups directly and leave written messages for these
individuals to receive. Computer mail systems enable the user to contact
receivers directly while other users are unaware.
Computer Bulletin Boards
Computer bulletin boards provide communication to anyone with access to the
bulletin board. The user provides messages or information without knowing who
will receive the information. Usually messages and information of general
subject matter or routine information that apply to most users are available on a
bulletin board. Most bulletin boards are controlled with minimal requirements for
access. Bulletin boards provide a means for communicating with a large diverse
group.
FCC AND DOE RULES AND REGULATIONS
When using communication systems licensed by the Federal Communications
Commission and operated by the Department of Energy, one cannot:
Section 7
• Use profane, indecent, or obscene language.
• Willfully damage or permit radio equipment damage.
• Cause malicious interference with any radio communications.
• Intercept and use or publish the contents of any radio message without the
permission of the proper authorities.
• Make unnecessary or unidentified transmissions.
• Transmit without first making sure that the transmission will not cause
harmful interference.
• Make any adjustments, repairs, or alterations to a radio transmitter without
licensing by the FCC or acceptable equivalent.
• Transmit a call sign, letter, or numeral which has not been assigned to
your station.
• Rebroadcast another transmission (i.e. radio station music).
2.02.04 Describe the FCC and DOE guidelines regarding proper use of communication
systems.
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-5
GENERAL ATTRIBUTES OF GOOD COMMUNICATIONS
• Minimize the use of abbreviations and acronyms. Only abbreviations and
acronyms from and approved list should be used in facility
communication.
• Make all oral instructions clear and concise. Do not include multiple
actions in a verbal instruction which may get confused or misunderstood.
• Ensure the identity of the person(s) is/are clearly understood. Identify
yourself and your position, and ensure that you know to whom you are
speaking.
• Use clear, precise terminology. Do not use slang terms. Avoid words that
sound alike. Use commonly agreed upon terms. Employ the phonetic
alphabet for clarification. (See Table 1)
Table 1. Phonetic Alphabet and Numbers
A - Alpha J - Juliett S - Sierra 1 - One
B - Bravo K - Kilo T - Tango 2 - Two
C - Charlie L - Lima U - Uniform 3 - Three
D - Delta M - Mike V - Victor 4 - Fower
E - Echo N - November W - Whiskey 5 - Fife
F - Foxtrot O - Oscar X - X-Ray 6 - Six
G - Golf P - Papa Y - Yankee 7 - Seven
H - Hotel Q - Quebec Z - Zulu 8 - Eight
I - India R - Romeo . - Point 9 - Niner
0 - Zero
2.02.05 Describe general attributes of good communications.
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-6
• Repeat back messages, either paraphrased or verbatim.
• Speak distinctly and deliberately.
• Acknowledge all communications.
CONTACT OF KEY PERSONNEL
The importance of knowing how to contact key personnel can not be understated.
The importance lies in getting the knowledgeable people at the location they are
needed. This can apply to emergency situations, routine circumstances, or
nonroutine circumstances. The ability of the RCT to contact key personnel can
reduce personnel injury, equipment damage, uncontrolled radioactive release,
unrestricted movement of controlled materials, and other important actions. The
RCT must be aware of the location of communication equipment, phone numbers
or pager numbers, and/or emergency numbers regardless of location. Familiarity
with the working environment will reduce the time needed to contact key
personnel. The RCT must be aware of the location, situation, and personnel or
equipment involved. This information must be relayed without misinterpretation
to key personnel to afford proper response.
SITE COMMUNICATION SYSTEMS
(Insert site specific information here.)
SITE EMERGENCY COMMUNICATIONS
(Insert site specific information here.)
Section 8
2.02.06 Explain the importance of knowing how to contact key personnel.
2.02.07 Identify the communication systems available at your site and methods available to
contact key personnel.
2.02.08 Describe the emergency communication systems available at your site.
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-7
SUMMARY
This lesson has covered topics related to effective communications, contacting
key personnel, and emergency communications. As an RCT you should be aware
of your location and what communication systems are available to you while
working on any job or situation.
DOE-HDBK-1122-2009
Module 2.02 Communications Systems Study Guide
2.02-8
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DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
Course Title: Radiological Control Technician
Module Title: Counting Errors and Statistics
Module Number: 2.03
Objectives:
(This document, Study Material, is referred to as Study Guide in the Program Management
Guide)
2.03.01. Identify five general types of errors that can occur when analyzing
radioactive samples, and describe the effect of each source of error on
sample measurements.
2.03.02. State two applications of counting statistics in sample analysis.
2.03.03. Define the following terms:
a. mode
b. median
c. mean
2.03.04. Given a series of data, determine the mode, median, or mean.
2.03.05. Define the following terms:
a. variance
b. standard deviation
2.03.06. Given the formula and a set of data, calculate the standard deviation.
2.03.07. State the purpose of a Chi-squared test.
→ 2.03.08. State the criteria for acceptable Chi-squared values at your site.
2.03.09. State the purpose of creating quality control (QC) charts.
→ 2.03.10. State the requirements for maintenance and review of QC charts at your
site.
2.03.11. State the purpose of calculating warning and control limits.
2.03.12. State the purpose of determining efficiencies and correction factors.
2.03.13. Given counting data and source assay information, calculate efficiencies
and correction factors.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
2.03.14. State the meaning of counting data reported as x ± y.
2.03.15. Given counting results and appropriate formulas, report results to desired
confidence level.
2.03.16. State the purpose of determining background.
→ 2.03.17. State the method and requirements for determining background for
counting systems at your site.
2.03.18. State the purpose of performing sample planchet maintenance.
→ 2.03.19. State the method and requirements for performing planchet maintenance
for counting systems at your site.
2.03.20. Explain methods to improve the statistical validity of sample
measurements.
2.03.21. Define "detection limit," and explain the purpose of using detection limits
in the analysis of radioactive samples.
→ 2.03.22. Given the formula and necessary information, calculate detection limit
values for counting systems at your site.
2.03.23. State the purpose and method of determining crosstalk.
→ 2.03.24. State the criteria for acceptable values of crosstalk for counting systems at
your site.
2.03.25. State the purpose of performing a voltage plateau.
Section 9
→ 2.03.26. State the method of performing a voltage plateau on counting systems at
your site.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
References:
1. "Advanced Health Physics Course Prestudy Guide," United States Nuclear
Regulatory Commission, General Physics Corporation, 1987.
2. Chase & Rabinowitz, "Principles of Radioisotope Methodology," 3rd Edition,
Burgess Publishing, 1987.
3. Gollnick, Daniel A., "Basic Radiation Protection Technology," 6th Edition,
Pacific Radiation Corporation, Altadena, CA, 2012.
4. Knoll, Glenn F., "Radiation Detection and Measurement," 4th Edition, John
Wiley & Sons, New York, 2010.
5. "Webster's New World Dictionary," 4thd College Edition, Webster's New World,
Cleveland & New York, 2003.
6. Moe, Harold, "Operational Health Physics Training," ANL-88-26; DOE; Argonne
National Laboratory, Chicago, 1988.
7. "Introduction to Low-background Counting Systems," Oxford-Tennelec
Instruments.
8. Environmental Implementation Guide for Radiological Survey Procedures--Draft;
DOE; February 1997.
9. Accuracy and Detection Limits for Bioassay Measurements in Radiation
Protection - Statistical Considerations; U.S. Nuclear Regulatory Commission
Office of Nuclear Regulatory Research; April 1986.
10. “Manual for Conducting Radiological Surveys in Support of License Termination
– Draft Report for Comment,” NUREG/CR-5849/ORAU-92/C57, June 1992.
11. “Multi-Agency Radiation Survey and Site Investigation Manual (MARSSIM),”
NUREG-1575, Rev. 1 / EPA 402-R-97-016, Rev. 1 / DOE/EH-0624, Rev. 1,
August 2000.
12. Multi-Agency Radiation Survey and Assessment of Materials and Equipment
Manual (MARSAME) (NUREG-1575, Supplement 1), January 2009.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
INTRODUCTION
Radiological sample analysis involves observation of a random process, one that may or may not
occur, and estimation of the amount of radioactive material present based on that observation.
All over the country radiation protection personnel are using activity measurements to make
decisions that may affect the health and safety of workers at those facilities and their surrounding
environments.
This unit presents an overview of measurement processes, and statistical evaluation of both
measurements and equipment performance. In addition, this unit addresses some of the actions
to take to minimize the sources of error in count room operations.
2.03.01 Identify five general types of errors that can occur when analyzing radioactive
samples, and describe the effect of each source of error on sample
measurements.
GENERAL SOURCES OF ERROR
Assuming the counting system is calibrated correctly, there are five general sources of error
associated with counting a sample:
1. Self-absorption
2. Backscatter
3. Resolving time
4. Geometry
5. Random disintegration of radioactive atoms (statistical variations).
Self-Absorption
When a sample has an abnormally large amount of material on the sample media (or the
sample itself is large), it could introduce a counting error due to self-absorption, which is
the absorption of the emitted radiation by the sample material itself. Self-absorption
could occur for:
• Liquid samples with a high solid content
• Air samples from a high dust area
• Use of improper filter paper may introduce a type of self-absorption, especially in
Section 10
alpha counting (i.e., absorption by the media, or filter).
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
Personnel counting samples should ensure the correct sample media is used, and that the
sample does not become too heavily loaded with sample material. Count room personnel
should be routinely checking samples for improper media or heavily loaded samples.
Backscatter
Counting errors due to backscatter occur when the emitted radiation traveling away from
the detector is reflected, or scattered back, to the detector by the material in back of the
sample. The amount of radiation that is scattered back will depend upon the type and
energy of the radiation and the type of backing material (reflector). The amount of
backscattered radiation increases as the energy of the radiation increases and as the
atomic number of the backing material increases. Generally, backscatter error is only a
consideration for particulate radiation, such as alpha and beta particles. Because beta
particles are more penetrating than alpha particles, backscatter error will be more
pronounced for beta radiation. The ratio of measured activity of a beta source counted
with a reflector compared to counting the same source without a reflector is called the
backscatter factor (BF).
counts − with − reflector
(Equation 1) BF =
counts − without − reflector
Normally, backscatter error is accounted for in the efficiency or conversion factor of the
instrument. However, if different reflector materials, such as aluminum and stainless
steel, are used in calibration and operation, an additional unaccounted error is introduced.
(This additional error will be about 6% for stainless steel versus aluminum.) Count room
personnel must be aware of the reflector material used during calibration of the counting
equipment. Any deviation from that reflector material will introduce an unaccounted
error and reduce confidence in the analysis results.
Resolving Time
Resolving time (or dead time) is the time interval which must elapse after a detector pulse
is counted before another pulse can be counted. Any radiation entering the detector
during the resolving time will not be recorded as a pulse; therefore, the information on
that radiation interaction is lost. As the activity, or decay rate, of the sample increases,
the amount of information lost during the resolving time of the detector is increased. As
the losses from resolving time increase, an additional error in the measurement is
introduced. Typical resolving time losses are shown in Table 1.
Table 1. Typical Resolving Time Losses
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
Count rate
(cpm) GM Tube
1 Proportional
2
Scintillation
3
20,000 1.7% < 1% < 1%
40,000 3.3% < 1% < 1%
60,000 5.0% < 1% < 1%
100,000 8.3% < 1% 1.0%
300,000 25.0% < 1% 3.5%
500,000 42.0% 1.5% 5.8%
1
GM tube: 50µs resolving time
2
Proportional detector: 2µs resolving time
3
Scintillation detector: 7µs resolving time
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Resolving time losses can be corrected by using the equation:
R
(Equation 2) R = o
1− R τ o
where: R = "true" count rate, in cpm
Ro = observed count rate, in cpm
τ = resolving time of the detector, in minutes ("tau")
Count room personnel should be aware of the limitations for sample count rate, based
Section 11
upon procedures and the type of detector in use, to prevent the introduction of additional
resolving time losses. This is especially true for counting equipment that uses GM
detectors.
Instructor note: A detector, or detection system, can be characterized by a paralyzable or non
paralyzable behaviour. In a non-paralyzable detector, an event happening during the dead time
since the previous event is simply lost, so that with an increasing event rate the detector will
reach a saturation rate equal to the inverse of the dead time. In a paralyzable detector, an event
happening during the dead time since the previous one will not just be missed, but will restart the
dead time, so that with increasing rate the detector will reach a saturation point where it will be
incapable of recording any event at all. A semi-paralyzable detector exhibits an intermediate
behaviour, in which the event arriving during dead time does extend it, but not by the full
amount, resulting in a detection rate that decreases when the event rate approaches saturation.
Geometry
Geometry related counting errors result from the positioning of the sample in relation to
the detector. Normally, only a fraction of the radiation emitted by a sample is emitted in
the direction of the detector because the detector does not surround the sample. If the
distance between the sample and the detector is varied, then the fraction of emitted
radiation which hits the detector will change. This fraction will also change if the
orientation of the sample under the detector (i.e., side-to-side) is varied.
An error in the measurement can be introduced if the geometry of the sample and
detector is varied from the geometry used during instrument calibration. This is
especially critical for alpha counting, where any change in the sample-to-detector
distance also increases (or decreases) the chance of attenuation of the alpha particles by
the air between the sample and detector.
Common sources examples of geometry-related errors include:
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• Piling smears and/or filters on top of each other in the same sample holder (moves
the top sample closer to the detector and varies the calibration geometry).
• Using deeper or shallower sample holders than those used during calibration
(changes the sample-to-detector distance).
• Adjusting movable bases in the counting equipment sliding drawer (changes the
sample-to-detector distance).
• Using too many or inappropriate sample holders or planchets (changes the
sample-to-detector distance). Sources not fixed in position can change geometry
and reduce reproducibility.
• Plexiglas shelving in counting chamber is improperly set.
Random Disintegration
The fifth source of general counting error is the random disintegration of the radioactive
atoms and constitutes the remainder of the lesson.
STATISTICS
Statistics is a branch of mathematics that deals with the organization, analysis, collection, and
interpretation of statistical data. No definition of statistical data is given. However, Webster's
does define a statistic as "an estimate of a variable, as an average or a mean, made on the basis of
a sample taken from a larger set of data."
This last definition is applicable to our discussion of counting statistics. After all, when we take
samples, we use the data derived from analysis of those samples to make determinations about
Section 12
conditions in an area, in water, in air, etc., assuming that the sample is representative.
So, we have estimated conditions (a variable) on the basis of a sample (our smear, water sample,
air sample) taken from a larger set of data.
Over the years, various methods and observations have identified three models which can be
applied to observations of events that have two possible outcomes (binary processes). Luckily,
we can define most observations in terms of two possible outcomes. For example, look at the
following table:
Table 2: Probability of Success
Trial Definition of Success Probability of Success
Tossing a coin "heads" 1/2
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Rolling a die
observing a given
radioactive nucleus for a
time, t
"a six"
The nucleus decays during
the observation
1/6
1-e -λt
For each of the processes that we want to study, we have defined a trial (our test), a success and
a failure (two possible outcomes), and have determined the probability of observing our defined
success.
Now, to study these processes, we can use proven, statistical models to evaluate our observations
for error. Consider the possibilities when throwing two dice. There are 36 possible outcomes
when throwing two dice, as indicated in Table 3.
Table 3. Possibilities in Rolling Dice
Result Possibilities No. of Possibilities
2 1&1 1
3 1&2,2&1 2
4 1&3,2&2,3&1 3
5 1&4,2&3,4&1,3&2 4
6 1&5,2&4,3&3,4&2,5&1 5
7 1&6,2&5,3&4,4&3,5&2,6&1 6
8 2&6,3&5,4&4,5&3,6&2 5
9 3&6,4&5,5&4,6&3 4
10 4&6,5&5,6&4 3
11 5&6,6&5 2
12 6&6 1
If, in our study of this process, we define a success as throwing a number between 2 and 12, the
outcome is academic. All trials will be successful, and we can describe the probabilities of
throwing any individual number between the range of 2 and 12 inclusive would add up to 1.
If we define a success as throwing a particular number, we can define the probability of our
success in terms of the number of possible outcomes that would give us that number in
comparison to the total number of possible outcomes.
If we were to take two dice, roll the dice a large number of times, and graph the results in the
same manner, we would expect these results to produce a curve such as the one shown in Figure
1.
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The area under the curve can be mathematically determined and would correspond to the
probability of success of a particular outcome. For example, to determine the probability of
throwing a particular number between 2 and 12 we would calculate the area under the curve
between 2 and 12. The results of that calculation are 36.
This is what statistics is all about; random binomial processes that should produce results in
certain patterns that have been proven over the years. The three models that are used are
distribution functions of binomial processes with different governing parameters. These
functions and their restrictions are:
• Binomial Distribution
This is the most general of the statistical models and is widely applicable to all processes
with a constant probability. It is not widely used in nuclear applications because the
mathematics is too complex.
• Poisson Distribution
A simplified version of binomial distribution is the Poisson (pronounced "pwusówn")
distribution, which is valid when the probability of success, P(x), is small. If we
Section 13
graphed a Poisson distribution function, we would expect to see the predicted number of
successes at the lower end of the curve, with successes over the entire range if sufficient
trials were attempted. Thus, the curve would appear as seen in Figure 2.
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The Poisson model is used mainly for applications involving counting system
background and detection limits, where the population (i.e., number of counts) is small.
This will be discussed in greater detail later.
• Gaussian Distribution
Also called the "normal distribution," the Gaussian (pronounced "Gowziun") distribution
is a further simplification which is applicable if the average number of successes is
relatively large, but the probability of success is still low. A graph of a Gaussian
distribution function is shown in Figure 3.
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Note that the highest number of successes is at the center of the curve, the curve is a bell
shaped curve, and the relative change in success from one point to the adjacent is small.
Also note that the mean, or average number of successes, is at the highest point, or at the
center of the curve.
The Gaussian, or normal, distribution is applied to counting applications where the mean
count or success is expected to be greater than 20. It is used for counting system
calibrations and operational checks, as well as for normal samples containing activity. It
may or may not include environmental samples (i.e., samples with very low activity).
2.03.02 State the two purposes for statistical analysis of count room operations.
APPLICATION OF STATISTICAL MODELS
Application of specific statistical methods and models to nuclear counting operations is termed
counting statistics and is essentially used to do two things:
• Predict the inherent statistical uncertainty associated with a single measurement,
thus allowing us to estimate the precision associated with that measurement.
• Serve as a check on the normal function of nuclear counting equipment.
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2.03.03 Define the following terms:
a. mode
b. median
c. mean
DEFINITIONS
Mode An individual data point that is repeated the most in a particular data set.
Median The center value in a data set arranged in ascending order.
Mean The average value of all the values in a data set.
2.03.04 Given a series of data, calculate mode, median, or mean.
DETERMINATION OF MODE, MEDIAN, AND MEAN
• Determination of the Mode: In the set of test scores above, a score of 95 occurs (i.e., is
repeated) more often than any other score.
• Determination of the Median: In the same set of test scores, this is the score in the
middle - where one half of the scores are below, and the other half are above the median.
The median for the test scores in Figure 4 is 90.
• Determination of the Mean: This is found by adding all of the values in the set together,
and dividing by the number of values in the set. The mean of the nine test scores is 89.
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Mean determination is often expressed using special symbols, as illustrated in the following
equation:
Σx
(Equation 3) x = i
n
2.03.05 Define the following terms:
a. variance
Section 14
b. standard deviation
2.03.06 Given the formula and a set of data calculate the standard deviation.
VARIANCE AND STANDARD DEVIATION
Using the Gaussian distribution model depicted in Figure 5 (below) we need to define the terms
"variance" and "standard deviation," which are both used as descriptors of the spread of the
population (or the data set) in a normal distribution.
E
f data points around the mean
, it tells how much the data "varies" from the mean.
al distribution, the standard deviation is
recise than the variance is
The standard deviation of a sample is defined mathematically
are located close to the mean, the curve will be tall and steep
value for a standard
ot as steep and have a larger numerical value for a standard
, it has been determined mathematically that 68.2% of the area
in the data point located at the mean ± (plus or minus) one
95.4% of the area under the curve falls between the data point
deviations (2
ated at ±
processes is that if the distribution (as depicted in Figure 5) is
ng function with a mean observable success >20 (Gaussian
the observed successes (or counts) will be within ±1 standard
ean.
the observed successes (or counts) will be within ±2 standard
ean.
D
Counting Errors an t'
amount of scatter e sample
. In other word an.
Mathematically, in a nor uare root
. A term more epresented by a
(pronounced “sigma”). athematically
=
If most of the data points tall and steep
and have a low numerica re scattered, the
curve will be lower and r a standard
In a Gaussian distributio .2% of the area
it inus) one
) the data point
two standard curve falls
point lo hat this means
to us in terms of countin in Figure 5) is
representative of a count (Gaussian
68.2% of the tim in ±1 standard
deviation of the
95.4% of the tim in ±2 standard
deviations of the
Stude
is defined as t
. In other words, it tells how much the data "varies" from the m
the s
,
(pronounced “sigma”). The standard deviation of a sample is defined
If most of the data points are located close to the mean, the curve will be
deviation. If data points
curve will be lower and not as steep and have a larger numerical value f
In a Gaussian distribution, it has been determined mathematically that 6
ithin the data point located at the mean ± (plus or
); 95.4% of the area under the curve falls betwee
), 99.97% of the area under the
) etc.
to us in terms of counting processes is that if the distribution (as depicte
representative of a counting function with a mean observable success >2
68.2% of the time the observed successes (or counts) will be wit
95.4% of the time the observed successes (or counts) will be wit
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Variance
The amount of scatter o of data points around the mean is defined as th he sample
variance. In other words s, it tells how much the data "varies" from the me ean.
Standard Deviation
Mathematically, in a norm mal distribution, the standard deviation is the sq quare root of the
variance. A term more p precise than the variance is standard deviation, r represented by a
σ (pronounced “sigma”). The standard deviation of a sample is defined m mathematically
as:
(Equation 4) σ = √(∑(xi )
2
/ (n - 1))
where: σ = standard deviation of a sample
xi = sample counts for each data point
= mean
n = number of data points
If most of the data points are located close to the mean, the curve will be tall and steep
Section 15
and have a low numericall value for a standard deviation. If data points a are scattered, the
curve will be lower and n not as steep and have a larger numerical value fo or a standard
deviation.
In a Gaussian distribution n, it has been determined mathematically that 68 8.2% of the area
under the curve falls with hin the data point located at the mean ± (plus or mminus) one
standard deviation (1 σ ); ; 95.4% of the area under the curve falls between n the data point
located at ± two standard deviations (2 σ ), 99.97% of the area under the curve falls
between the data point loccated at ± three standard deviations (3 σ ) etc. WWhat this means
to us in terms of counting g processes is that if the distribution (as depicted d in Figure 5) is
representative of a counti ing function with a mean observable success >200 (Gaussian
distribution):
• 68.2% of the time e the observed successes (or counts) will be with hin ±1 standard
deviation of the m mean.
• 95.4% of the time e the observed successes (or counts) will be with hin ±2 standard
deviations of the m mean.
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• 99.97% of the time the observed successes (or counts) will be within ±3 standard
deviations of the mean.
Remember, the area of the curve represents the probability of success in a random
process. In radiation protection this random process is the decay of a radioactive sample.
The known statistical distribution is used in radiation protection when setting up a
counting system and in evaluating its operation by means of daily pre-operational source
checks. In performing the calibration of the system, a radioactive source with a known
activity is counted twenty times for one minute each time. Using the data from the
twenty counts, the mean and standard deviation can be calculated. The mean can then be
used to determine the efficiency of the system while allowing for a certain number of
standard deviations during operation. The twenty counts can also be used to perform
another required test of the system's performance, the chi-squared test (see below).
Example 2.03-1
Calculate the mean and sample standard deviation for the following data set:
193, 188, 202, 185, 179, 217, 191 199, 201, 214,
193, 232, 199, 210, 196, 211, 191, 203, 201, 195
2.03.07 State the purpose of a Chi-squared test.
CHI-SQUARED TEST
The Chi-squared test (pronounced "ki") is used to determine the precision of a counting system.
Precision is a measure of exactly how a result is determined without regard to its accuracy. It is
a measure of the reproducibility of a result, or in other words, how often that result can be
repeated, or how often a "success" can be obtained.
This test results in a numerical value, called the Chi-squared value (X
2
), which is then compared
to a range of values for a specified number of observations or trials. This range represents the
2
expected (or predicted) probability for the chosen distribution. If the X value is lower than the
expected range, this tells us that there is not a sufficient degree of randomness in the observed
data. If the value is too high, it tells us that there is too much randomness in the observed data.
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The Chi-squared test is often referred to as a "goodness-of-fit" test. If it does NOT fit a curve
Section 16
indicating sufficient randomness, then the counting instrument may be malfunctioning.
The Chi-squared value is calculated as follows:
∑ ( x − x)
2
i
(Equation 5) X
2 =
x
Example 2.03-2
Using the data from Example 2.03-1, determine the Chi-squared value for the data set.
2.03.08 State the criteria for acceptable Chi-squared values at your site.
(Insert site-specific information here.)
Assuming a given set of data passes the Chi-squared test, the data can then be used to prepare
quality control charts for use in verifying the consistent performance of the counting system.
2.03.09 State the purpose of creating quality control (QC) charts.
2.03.10 State the requirements for maintenance and review of QC charts at
QUALITY CONTROL CHARTS
Quality control charts may be prepared using source counting data obtained during system
calibration. Obviously since this test verifies that the equipment is still operating within an
expected range of response, we cannot change the conditions of the test in mid-stream. QC
charts, then, enable us to track the performance of the system while in use.
Data that can be used for quality control charts include gross counts, counts per unit time, and
efficiency. Most nuclear laboratories use a set counting time corresponding to the normal
counting time for the sample geometry being tested.
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When the system is calibrated and the initial calculations performed, the numerical values of the
mean ± 1, 2, and 3 standard deviations are also determined.
Using graph paper or a computer graphing software, lines are drawn all the way across the paper
at those points corresponding to the mean, the mean plus 1, 2, and 3 standard deviations, and the
mean minus 1, 2, and 3 standard deviations. The daily control check results are then plotted on
the control chart to see if the results fall outside the limits
(Insert site-specific information here.)
2.03.11 State the purpose of calculating warning and control limits.
SYSTEM OPERATING LIMITS
The values corresponding to ±2 and ±3 standard deviations may be called the upper and lower
warning and control limits, respectively (or other terms such as action limits) . The results of the
daily source counts are graphed in many countrooms. Most of the time results will lie between
the lines corresponding to ±1 standard deviation (68.2%). We also know that 95.4% of the time
our count will be between ±2 standard deviations and that 99.97% of the time our count will be
between ±3 standard deviations.
Counts that fall outside the warning limit (±2 σ ) are not necessarily incorrect. Statistical
distribution models say that we should get some counts in that area. Counts outside the warning
limits indicate that something MAY be wrong. The same models say that we will also get some
outside the control limits (±3 σ ). However, not very many measurements will be outside those
limits. We use 3 σ as the control – a standard for acceptable performance. In doing so we say
that values outside of ±3 σ indicate unacceptable performance, even though those values may be
statistically valid.
True randomness also requires that there be no patterns in the data that are obtained; some will
be higher than the mean, some will be lower, and some will be right on the mean.
When patterns do show up in quality control charts, they are usually indicators of systematic
error. For example:
Section 17
• Multiple points outside two sigma
• Repetitive points (n out of n) outside one sigma
• Multiple points, in a row, on the same side of the mean
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• Multiple points, in a row, going up or down.
The assumption is made that systematic error is present in our measurements, and that our
statistical analysis has some potential for identifying its presence. However, industry assumption
is that systematic error that is present is very small in comparison to random error.
Quality control charts should be maintained in the area of the radioactivity counting system such
that they will be readily accessible to those who operate the system. These charts can then be
used by operators to determine if routine, periodic checks (typically daily) have been completed
before system use.
2.03.12 State the purpose of determining efficiencies and correction factors.
2.03.13 Given counting data and source assay information, calculate efficiencies and
correction factors.
COUNTER EFFICIENCY
A detector intercepts and registers only a fraction of the total number of radiations emitted by a
radioactive source. The major factors determining the fraction of radiations emitted by a source
that are detected include:
• The fraction of radiations emitted by the source which travel in the direction of the
detector window
• The fraction emitted in the direction of the detector window which actually reach the
window
• The fraction of radiations incident on the window which actually pass through the
window and produce an interaction
• The fraction scattered into the detector window
All radiation detectors will, in principle, produce an output pulse for each particle or photon
which interacts within its active volume. Because of the factors outlined above, only a fraction
of the disintegrations occurring in a source result in counts being reported by the detector.
Therefore, there is only a certain fraction of the disintegrations occurring that results in counts
reported by the detector. Using a calibrated source with a known activity, a precise figure can be
determined for this fraction. This value can then be used as a ratio in order to relate the number
of pulses counted to the number of particles and/or photons emitted by the source. This ratio is
called the efficiency.
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The detector efficiency gives us the fraction of counts detected per disintegration, or c/d. Since
activity is the number of disintegrations per unit time, and the number of counts are detected in a
finite time, the two rates can be used to determine the efficiency if both rates are in the same
units of time. Counts per minute (cpm) and disintegrations per minute (dpm) are the most
common.
Thus, the efficiency, E, can be determined as shown in Equation 6. Used in this manner the time
units will cancel, resulting in counts/disintegration (c/d).
cpm c
(Equation 6) E = =
dpm d
The efficiency obtained in the formula above will be in fractional or decimal form. To calculate
the percent efficiency, the fraction can be multiplied by 100. For example, an efficiency of 0.25
would mean 0.25 × 100, or 25%.
Example 2.03-3
A source is counted and yields 2840 counts per minute. If the source activity is
known to be 12,500 dpm calculate the efficiency and percent efficiency.
Section 18
By algebraic manipulation, Equation 6 can be solved for the disintegration rate (see Equation 7).
The system efficiency is determined as part of the calibration. When analyzing samples, a count
rate is reported by the counting system. Using Equation 7, the activity, (A), of the sample can be
determined in dpm, and then converted to any other units of activity (e.g., Ci, Bq).
cpm cpm
(Equation 7) dpm =
E
⎯⎯→ dpm A =
E
Example 2.03-4
A sample is counted on a system with a 30% efficiency. If the detector reports 4325
net counts per minute what is the activity of the sample in dpm?
A correction factor (CF), which is simply the inverse of the efficiency, is used by multiplying it
by the net count rate to determine the activity, as in Equation 8.
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1
(Equation 7) CF =
E
Example 2.03-5
An instrument has an efficiency of 18%. What is the correction factor?
This count-rate correction factor should not be confused with a geometry correction factor used
with some radiation instruments, such as the beta correction factor for a Cutie Pie (RO-3C).
2.03.14 State the meaning of counting data reported as x.xx ± yy.
2.03.15 Given counting results and appropriate formulas, report results to desired
confidence level.
ERROR CALCULATIONS
The error present in a measurement governed by a statistical model can be calculated using
known parameters of that model. Nuclear laboratories are expected to operate at a high degree
of precision and accuracy. However, since we know that there is some error in our
measurements, we are tasked with reporting measurements to outside agencies in a format that
identifies that potential error. The format that is used should specify the activity units and a
range in which the number must fall. In other words, the results would be reported as a given
activity plus or minus the error in the measurement. Since nuclear laboratories prefer to be right
more than they are wrong, counting results are usually reported in a range that would be correct
95% of the time, or at a 95% confidence level.
In order to do this, the reported result should be in the format:
(Equation 9) x.xx ± yy (K σ )
where: x.xx = measured activity, in units of dpm, Ci, or Bq
yy = associated potential (or possible) error in the measurement
K = multiple of counting error
σ = standard deviation at stated confidence level (CL)
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Note: Use of K σ is only required for confidence levels other than 68% (see Table 4). Therefore:
σ = 1× σ 68% CL (optional)
1.64 σ = 1.64 × σ 90% CL (sometimes used)
2 σ = 1.96 × σ 95% CL (normally used)
For example, a measurement of 150 ± 34 dpm (2 σ ) indicates the activity as 150 dpm; however,
it could be as little as 116 dpm or as much as 184 dpm with 95% confidence (at 2 σ ).
The calculations of the actual range of error are based on the standard deviation for the
distribution. In the normal (or Gaussian) distribution, the standard deviation of a single count is
defined as the square root of the mean, or σ = x . The error, e, present in a single count is
some multiplier, K, multiplied by the square root of that mean, i.e., some multiple times the
standard deviation, K σ . The value of K used is based on the confidence level that is desired,
and is derived from the area of the curve included at that confidence level (see Figure 5).
Section 19
Common values for K include:
Table 4. Counting Error Multiples
Error
Confidence
Level
K
Probable 50% 0.6745
Standard 68% 1.0000
9/10 90% 1.6449
95/100 95% 1.9600
99/100 99% 2.5750
To calculate the range to the point at which you would expect to be right 95% of the time, you
would multiply the standard deviation by 1.96, and report the results of the measurement as x.xx
dpm ± yy dpm (2 σ ). Note that using a 68% or 50% confidence level introduces an expected
error a large percentage of the time. Therefore, for reasonable accuracy a higher confidence
level must be used.
The simple standard deviation (σ) of the single count (x) is usually determined as a count rate
(counts per unit time). This is done by dividing the count rate (R) by the count time (T).
Subscripts can be applied to distinguish sample count rates from background count rates.
(Equation 10) σ = K
R
T
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Example 2.03-6
The count rate for a sample was 250 cpm. Assume 10 minute counting time, zero background
counts and a 25% efficiency. Report sample activity at a 95% C.L.
2.03.16 State the purpose of determining background.
BACKGROUND
Determination of Background
Radioactivity measurements cannot be made without consideration of the background.
Background, or background radiation, is the radiation that enters the detector
concurrently with the radiation emitted from the sample being analyzed. This radiation
can be from natural sources, either external to the detector (i.e., cosmic or terrestrial) or
radiation originating inside the detector chamber that is not part of the sample.
In practice, the total counts are recorded by the counter. This total includes the counts
contributed by both the sample and the background. Therefore, the contribution of the
background will produce an error in radioactivity measurements unless the background
count rate is determined by a separate operation and subtracted from the total activity, or
gross count rate. The difference between the gross and the background rates is called the
net count rate (sometimes given units of ccpm, or corrected counts per minute). This
relationship is seen in the following equation:
(Equation 11) R = R − RS S +B B
where: RS = net sample count rate (cpm)
RS+B = gross sample count rate (cpm)
RB = background count rate (cpm)
The background is determined as part of the system calibration by counting a background
(empty) sample holder for a given time. The background count rate is determined in the
same way as any count rate, where the gross counts are divided by the count time, as seen
in Equation 12 below.
(Equation 12) R
B
=
N
B
TB
where: RB = background count rate (counts per time, i.e., cpm)
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NB = gross counts, background
TB = background count time
In practice, background values should be kept as low as possible. As a guideline,
background on automatic counting systems should not be allowed to exceed 0.5 cpm
alpha and 1 cpm beta-gamma. If system background is above this limit the detector
should be cleaned or replaced.
Reducing Background
Typically, the lower the system background the more reliable the analysis of samples will
be. In low-background counting systems the detector housing is surrounded by lead
shielding so as to reduce the background. Nonetheless, some background still manages
Section 20
to reach the detector. Obviously, little can be done to reduce the actual source of
background due to natural sources. On many systems a second detector is incorporated
to detect penetrating background radiation. When a sample is analyzed the counts
detected by this second detector during the same time period are internally subtracted
from the gross counts for the sample.
Background originating inside the detector chamber can be, for the most part, more easily
controlled. The main contributors of this type of background are:
• Radiation emitted from detector materials
• Radioactive material on inside detector surfaces
• Radioactive material on the sample slide assembly
• Contamination in or on the sample planchet or planchet carrier
There are, unfortunately, trace levels of radioactivity in the materials of which detectors
and their housings are made. This is simply a fact of life in the atomic age.
The contribution to background from such materials is negligible, but should nonetheless
be acknowledged.
Radioactive material can be transferred from contaminated samples to the inside surfaces
of the detector chamber during counting. This usually occurs when samples having gross
amounts of material on them are counted in a low-background system. During the
insertion and withdrawal of the sample into the detector chamber, loose material can be
spread into the chamber. In order to prevent this, these samples should be counted using
a field survey instrument or a mini-scaler. Low-background systems are designed for
counting lower-activity samples. Counting of a high-activity sample on these systems
should be avoided unless it is a sealed radioactive source.
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(Insert site-specific information here.)
Note: The following is provided as an example as a typical counting system.
Radioactive material can also be transferred from contaminated samples to the slide
assembly upon which samples are inserted into, and withdrawn from, the detector
chamber.
This can be prevented in the same way as stated above. In addition, when loading and
stacking samples for counting, ensure that the slide assembly cover is in place. The slide
assembly should also be cleaned on a routine basis (i.e., weekly).
When loading and unloading samples into and from planchets, material from the samples
can be spread to the planchet and/or the carrier. Most smears and air samples are 47-mm
diameter and are counted in a planchet that is almost the same size. The planchet is
placed in a carrier which surrounds and supports the planchet and allows for automatic
sample exchange by the counting system. When a sample is counted, the entire carrier is
placed under the detector window inside the detector chamber. Any contamination on
the carrier (or in the planchet) is counted with, and attributed to, the sample.
A paper disc can be placed in the bottom of the planchet as a step in preventing transfer
of material from samples to the planchet. Care should be taken when loading and
unloading samples such that material remains on the sample media.
2.03.17 State the method and requirements for determining background for counting
systems at your site.
(Insert site-specific information here.)
2.03.18 State the purpose of performing planchet maintenance.
PLANCHET MAINTENANCE
Planchets and carriers should be inspected, cleaned, and counted on a routine basis. All in-use
Section 21
planchets and carriers must read less than established site limits. Planchets exceeding these
limits should be decontaminated and recounted as necessary.
By maintaining planchets clean and as free from contamination as possible, sample result
reliability will be increased because the amount of error introduced in the sample analysis will be
reduced.
2.03.19 State the method and requirements for performing planchet maintenance for
counting systems at your site.
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Module 2.03 Counting Errors and Statistics Student's Material
PROPAGATION OF ERROR
The error present in a measurement includes the error present in the sample count and the error
present in the background count. The total error in the measurement is calculated by squaring
the error in the background and adding that to the square of the error in the sample count, and
taking the square root of the sum, as shown in Equation 13.
(Equation 13) e = e 2 + e 2
S S + B B
where: eS = error present in the measurement (sample)
eS+B = error in sample count (sample plus background)
eB = error present in background count
Since we normally use this equation in terms of a count rate, the formula is slightly modified as
follows, and the error stated as the sample standard deviation (σ S):
R RS +B B(Equation 14) Kσ S = K +
TS TB
where: RS+B = gross sample count rate (sample plus background)
RB = background count rate
TS = sample count time
TB = background count time
K = confidence level multiple (see Table 4)
The error in the sample count is the standard deviation of the count, which is the square root of
that count (see Equation 13 above). Example 2.03-7
An air sample is counted and yields 3500 counts for a 2-minute count period. The system
background is 10 cpm determined over a 50-minute count time. Determine the error in the
sample and report the net count rate to 95% confidence level.
If the sample counting time and the background counting time is the same, the formula can be
simplified even more to:
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Module 2.03 Counting Errors and Statistics Student's Material
R + RS +B B(Equation 15) Kσ = K s
T
Example 2.03-8
A long-lived sample is counted for one minute and gives a total of 562 counts. A one
minute background gives 62 counts. Report net sample count rate to 95% CL.
2.03.20 Explain the methods used to improve the statistical validity of count room
measurements.
IMPROVING STATISTICAL VALIDITY OF COUNT ROOM MEASUREMENTS
Minimizing the statistical error present in a single sample count is limited to several options. If
we look at the factors present in the calculation below (same as Equation 14), we can see that
there are varying degrees of control over these factors. The standard deviation is calculated here
in terms of count rate.
R RS +B Bσ rate = +
TS TB
RS+B is the sample count rate. We really have no control over this.
RB is the background count rate. We do have some control over this. On any counting
equipment the background should be maintained as low as possible. In most of our counting
applications, however, the relative magnitude of the background count rate should be extremely
small in comparison to the sample count rate if proper procedures are followed. This really
becomes an issue when counting samples for free release or environmental samples. However,
some reduction in error can be obtained by increasing the background counting time, as
Section 22
discussed below.
TB and TS are the background and sample counting times, respectively. These are the factors that
we have absolute control over. In the previous section we talked about the reliability of the
count itself. We have been able to state that a count under given circumstances may be
reproduced with a certain confidence level, and that the larger the number of counts the greater
the reliability. The condition we have been assuming is that our count is taken within a given
time. In order to get more precise results, many counts must be observed. Therefore, if we have
low count rates, the counting time must be increased in order to obtain many counts, thereby
making the result more precise (or reproducible).
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
The total counting time required depends upon both the sample and background count rates. For
high sample activities the sample count time can be relatively short compared to the background
count time. For medium count rates we must increase the sample count time in order to increase
precision. As the sample activity gets even lower, we approach the case where we must devote
equal time to the background and source counts. In other words, by counting low activity
samples for the same amount of time as that of the background, we increase the precision of our
sample result. However, we must never count a sample for a period of time longer than the
system background.
In summary, by minimizing the potential error present, we improve statistical validity of our
measurements.
2.03.21 Define "detection limit," and explain the purpose of using detection limits in
the analysis of radioactive samples.
DETECTION LIMITS
The detection limit of a measurement system refers to the statistically determined quantity of
radioactive material (or radiation) that can be measured (or detected) at a preselected confidence
level. This limit is a factor of both the instrumentation and technique/procedure being used.
The two parameters of interest for a detector system with a background response greater than
zero are (see Figure 6):
LC Critical detection level: the response level at which the detector output can be
considered "above background"
LD Minimum significant activity level, i.e., the activity level that can be seen with a
detector with a fixed level of certainty
These detection levels can be calculated by the use of Poisson statistics, assuming random errors
and systematic errors are separately accounted for, and that there is a background response. For
these calculations, two types of statistical counting errors must be considered quantitatively in
order to define acceptable probabilities for each type of error:
Type I - occurs when a detector response is considered above background when in fact it is
not (associated with LC)
Type II - occurs when a detector response is considered to be background when in fact it is
greater than background (associated with LD)
2.71
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
If the two probabilities (areas labeled I and II in Figure 6) are assumed to be equal, and the
background of the counting system is not well-known, then the critical detection level (LC) and
the minimum significant activity level (LD) can be calculated. The two values would be derived
using the equations LC = kσB and LD = k
2
Section 23
+ 2kσB, respectively. If 5% false positives (Type I
error) and 5% false negatives (Type II error) are selected to be acceptable levels, i.e., 95%
confidence level, then k = 1.645 and the two equations can be written as:
RB RB(Equation 16) LC = 1.645 +
TB TS
R R3 B B(Equation 17) LD = + 3.29 +
TS TB TS
where: LC = Critical detection level
LD = a priori detection limit [minimum significant activity level
RB = background count rate
TB = background count time
TS = sample count time
2.71
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
The minimum significant activity level, LD, is the a priori (before the fact) activity level that an
instrument can be expected to detect 95% of the time. In other words, it is the smallest amount
of activity that can be detected at a 95% confidence level. When stating the detection capability
of an instrument, this value should be used.
The critical detection level, LC, is the lower bound on the 95% detection interval defined for LD,
and is the level at which there is a 5% chance of calling a background value "greater than
background." This value (LC) should be used when actually counting samples or making direct
radiation measurements. Any response above this level should be counted as positive and
reported as valid data. This will ensure 95% detection capability for LD.
If the sample count time (TS) is the same as the background count time (TB), then equations 16
and 17 can be simplified as follows:
(Equation 18) LC = 2.32
RB
T
R
(Equation 19) LD = 3 + 4.65 B
T T
where: T = count time (sample and background)
Therefore, the full equations for LC and LD must be used for samples with count times differing
from the background determination time (95% CL used). These equations assume that the
standard deviation of the sample planchet/carrier background during the sample count (the
planchet/carrier assumed to be 0 activity) is equal to the standard deviation of the system
background (determined using the background planchet/carrier).
The critical detection level, LC, is used when reporting survey results. It is used to say that at a
95% confidence level, samples above this value are radioactive. This presupposes, then, that 5%
of the time clean samples will be considered radioactive.
The minimum significant activity level, LD, [also referred to as the LLD (Lower Limit of
Detection) in some texts] is calculated prior to counting samples. This value is used to determine
minimum count times based on release limits and airborne radioactivity levels. In using this
value we are saying that at a 95% CL, samples counted for at least the minimum count time
calculated using the LD that are positive will indeed be radioactive (above the LC). This
presupposes, then, that 5% of the time samples considered clean will actually be radioactive.
Example 2.03-9
A background planchet is counted for 50 minutes and yields 16 counts. Calculate the critical
detection level and the minimum significant activity level for a 0.5 minute sample count time.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
2.03.22 Given the formula and necessary information, calculate detection limit values
for counting systems at your site.
MINIMUM DETECTABLE ACTIVITY (MDA)
The minimum significant activity level, LD , can be used to evaluate whether the measurement
Section 24
process is adequate to meet requirements. For example, the results of Example 2.03-9 (in units
of cpm) can be converted using counting efficiency and area of swipe to determine the adequacy
of the measurement system for contamination surveys for removable contamination performed to
ensure that the removable surface contamination values specified in Appendix D of 10 CFR 835
are not exceeded (in units of dpm/100cm
2
).
In most cases, swipes to determine the removable contamination levels will be counted in the
field or submitted to the counting lab for analysis where the background radiation levels are
sufficiently low enough to ensure that LD, and thus MDA, are below the limits in 10 CFR 835
Appendix D.
(Equation 19b) MDAremovable = LD x (100/Aswipe) / e
where:
MDAremovable = Activity level in dpm/100 cm
2
e = Detector efficiency in counts per disintegration
Aswipe = Area of surface swiped in cm
2
Static Count MDAs
Similarly, one can calculate a MDA for a static field measurement to evaluate total surface
contamination values. In this case, an adjustment is needed to account for the size of the
detector. To determine the MDA for static counts, i.e., the probe is stationary for a prescribed
period of time, Equation 19c is used.
(Equation 19c) MDAtotal = LD x (100/Aprobe) / e
where:
MDAtotal = Activity level in dpm/100 cm
2
e = Detector efficiency in counts per disintegration
Aprobe = Surface area of probe in cm
2
Scanning MDA
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
The ability to identify a small region or area of slightly elevated radiation during surface
scanning is dependent upon the RCT’s skill in recognizing an increase in the audible output of
the instrument. Experience has shown that a 25% to 50% increase may be easily identifiable at
ambient background levels of several thousand counts per minute, whereas, at ambient levels of
a few counts per minute, a two to three fold increase in the audible signal is required before a
change is readily recognizable. The detection sensitivity of scanning is dependent upon a
number of other factors, such as detector scan speed, surface characteristics, size of elevated
activity region, surveyor efficiency, level of activity, and detector/surface distance.
The ability to detect an elevated region of activity using a particular survey scanning technique
would need to be determined empirically and is beyond the scope of this training.
(Insert site-specific information here.)
2.03.23 State the purpose and method of determining crosstalk.
CROSSTALK
Discrimination
Crosstalk is a phenomenon that occurs on proportional counting systems (such as a
Tennelec) that employ electronic, pulse-height discrimination, thereby allowing the
simultaneous analysis for alpha and beta-gamma activity. Discrimination is
accomplished by establishing two thresholds, or windows, which can be set in accordance
with the radiation energies of the nuclides of concern. Recall that the pulses generated by
alpha radiation will be much larger than those generated by beta or gamma. This makes
the discrimination between alpha and beta-gamma possible. Beta and gamma events are
difficult to distinguish; hence, they are considered as one by such counting systems.
In practice, the lower window is set such that electronic noise and ultra-low-energy
photon events are filtered out. Any pulse generated whose size is greater than the setting
Section 25
for the lower window is considered an event, or a count. The upper window is then set
such that any pulses which surpass the upper discriminator setting will be considered an
alpha count (see Figure 7).
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
For output purposes, the system routes each count to a series of channels which simply
keep a total of the counts routed to them. Channel A is for alpha counts, Channel B is
beta-gamma counts, and Channel C is total counts. As a sample is being counted, all
valid counts registered (i.e., those which surpass the lower discriminator setting) are
routed to the C-channel. In addition, if the count was considered an alpha count (i.e., it
surpassed the upper discriminator setting) it is routed to the A-channel; else it is tallied in
the B-channel. In effect, what occurs is that the number of beta-gamma counts (Channel
B) are determined by subtracting the number of alpha counts (Channel A) from the total
counts (Channel C), or B = C - A.
Origin of Crosstalk
Now that we understand the process involved, there is a dilemma that stems from the fact
that events are identified by the system as either alpha or beta-gamma according to the
size of the pulse generated inside the detector. The system cannot really tell what type of
radiation has generated the pulse. Rather, the pulse is labeled as "alpha" or "beta
gamma" by comparing the size of the pulse to the discriminator setting. It is the setting
of the discriminator that poses the dilemma.
Alpha particles entering the detector chamber generally are attenuated by the detector
fill-gas because of their high LET, thereby producing a large pulse. Low-energy beta
particles and photons will also lose all their energy within the detector gas, but
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
nevertheless produce a smaller pulse because of their lower energies. High energy beta
particles can still retain some of their energy even after having produced a pulse while
traversing the detector volume. Rather than leaving the detector, as would a photon, the
beta is reflected off of the detector wall and reenters the volume of gas, causing
ionizations and generating a second pulse. These two pulses can be so close together that
the detector sees them as one large pulse. Because of the large pulse size it can surpass
the upper discriminator setting and is, therefore, counted as an alpha, and not as a beta.
The result is that alpha activity can be reported for a sample when in fact there was little
or no alpha present. Conversely, if a true alpha-generated pulse is not large enough so as
to exceed the upper discriminator, it would be counted as a beta-gamma event. This is
crosstalk.
The solution is not a simple one. The setting of the upper discriminator depends on the
radiations and energies of the sources and samples being analyzed. If high energy beta
radiations are involved, a significant portion of them could be counted as alpha events if
the setting is too low. If the setting is too high, lower-energy alpha events could be
counted as beta-gamma. Typically, the setting of the discriminator will usually be some
"happy medium." A discussion of how this can be dealt with is in order.
Calibration Sources and Crosstalk
For calibrations of Tennelec counting systems, the manufacturer provides the following
Section 26
general recommendations for discriminator settings: First, using a Strontium-90 beta
source, set the upper (A) discriminator such that there is 1% beta-to-alpha crosstalk.
Then, using a Polonium-210 alpha source, set the A+B discriminator such that there is
less than 3% alpha-to-beta crosstalk.
Energies of sources used to calibrate counting systems should be the same as, or as close
as possible to, the energies of radionuclides in the samples analyzed. Wherever possible
they should be a pure emitter of the radiation of concern.
For beta-gamma sources the most popular isotope in radiation protection is Sr-90. It has
a relatively long half-life of 29.1 years, but emits betas of only 546 keV. However, Sr-90
decays to Yttrium-90, another beta emitter which has a short half-life of only 2.67 days
and emits a 2.281 MeV beta. Y-90 decays to Zirconium-90m which emits a 2.186 Mev
gamma almost instantaneously to become stable. The daughters reach equilibrium with
the strontium parent within a number of hours after source assay. Hence, for every Sr
beta emitted a Y beta is also emitted, thereby doubling the activity. These sources are
often listed as Sr/Y-90 for obvious reasons. This makes Sr/Y-90 sources an excellent
choice and they are used by many sites for calibrations and performance testing.
Po-210 is essentially a pure alpha emitter. This is primarily the reason why it is
recommended for calibrations and performance testing. It yields a strong alpha, but it
also has a short half-life. A comparison of some alpha emitters is given in Table 5.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
Table 5. Alpha Emitters
Isotope Half-Life Energy (MeV)
Po-210 138.38 days 5.3044
Pu-239 2.4E4 years 5.156, 5.143, 5.105
Ra-226 1.60E3 years 4.78, 4.602
Th-230 7.54E4 years 4.688, 4.621
Natural U 4.4E9 years (avg.) 4.2 (avg.)
2.03.24 State the criteria for acceptable values of crosstalk for counting systems at
your site
(Insert site-specific information here.)
VOLTAGE PLATEAUS
Very simply put, a voltage plateau is a graph that indicates a detector's response to a specific
energy particle with variations of high voltage. The x-axis represents the high voltage and the
y-axis the response (i.e., counts). The resulting curve gives an indication of detector quality, and
can indicate problems with the counting gas should they be present. The curve can also be used
to determine the optimum operating high voltage for the system.
Most automatic low-background counting systems provide several different analysis modes.
These modes count samples at certain pre-determined voltages. Counting systems generally
provide three analysis modes:
• ALPHA ONLY
• ALPHA THEN BETA
• ALPHA AND BETA (SIMULTANEOUS)
There are usually two voltage settings used in conjunction with these analysis modes:
• Alpha voltage (lower)
• [Alpha plus] Beta voltage (higher)
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
Recall that in a proportional counter the amount of voltage determines the amount of gas
multiplication. Because of the high LET of alpha radiation, at a lower voltage, even though the
gas amplification will be lower, alpha pulses will still surpass the lower discriminator and some
will even pass the upper discriminator. Because of the lower gas amplification beta-gamma
pulses will not be large enough to be seen. Therefore, any counts reported for the sample will be
Section 27
alpha counts.
In the ALPHA ONLY mode, the sample is counted once, at the alpha voltage. Counts may
appear in either the A or B channels. Upon output, the A and B channels will be added together
and placed in Channel A and, therefore, reported as alpha counts; the B channel will be cleared
to zero, thereby resulting in no beta-gamma counts.
In the ALPHA THEN BETA mode, the sample is counted twice. The first count interval
determines the alpha counts using the alpha voltage. The second count is done at the beta
voltage. The determination of alpha and beta-gamma counts in this mode is based strictly on the
operating characteristics of the detector at the different voltages. For this reason, the A and B
counts are summed during both counting intervals to attain the total counts. The separation of
alpha and beta-gamma counts is then calculated and reported according to the following formula:
A + B
α = 1 1
(Equation 20) CF α
β = ( A − B ) − α2 2
where: α = reported gross alpha counts
β = reported gross beta-gamma counts
A1,B1 = accumulated channel counts respectively, 1st interval
A2,B2 = accumulated channel counts respectively, 2nd interval
CFα = alpha correction factor (ratio of alpha efficiency at alpha
voltage to efficiency at beta voltage)
In the ALPHA AND BETA (SIMULTANEOUS) mode, the sample is counted once using the
beta voltage. Alpha events are reported in the A channel, while beta-gamma counts are reported
in the B channel. This is the mode used most often.
As can be seen, the setting of the two voltages will have a direct impact on the number of counts
reported for a given sample. The determination of what these voltage settings should be must be
done such that the optimum performance of the detector is obtained for those voltage regions.
This is the purpose of a plateau.
2.03.26 State the method of performing a voltage plateau on counting systems at your
site.
DOE-HDBK-1122-2009 (Revised 2013)
Module 2.03 Counting Errors and Statistics Student's Material
(Insert site-specific information here.)
In conjunction with initial system setup and calibration by the vendor, two voltages plateaus are
performed--alpha voltage and beta voltage. For P-10 gas the alpha plateau is started at about 400
volts and the beta plateau at about 900 volts. The plateaus are developed by plotting the gross counts
accumulated for each radionuclide. Each time that a count is completed, the high voltage is
incremented a specific amount, typically 25 to 50 volts, and another count is accumulated. This
is repeated until the end of the range is reached, typically about 1800 volts.
With the high voltage set at the starting point, few or no counts are observed because of
insufficient ion production within the detector. As the voltage is increased, a greater number of
pulses are produced with sufficient amplitude to exceed the discriminator threshold, and are then
accumulated in the counter. There will be a high voltage setting where the increase in counts
levels off (see Figure 8). This area is the detector plateau. Further increases in high voltage
result in little change in the overall count rate. The plateau should remain flat for at least 200
volts using a Sr/Y-90 source, and this indicates the plateau length. Between 1750 and 1850 volts
the count rate will start to increase dramatically. This is the avalanche region, and the high
voltage should not be increased any further.
DOE-HDBK-1122-2009 (Revised 2013)
Section 28
Module 2.03 Counting Errors and Statistics Student's Material
The region where the counts level off is called the knee of the plateau. The operating voltage is
chosen by viewing the plateau curve and selecting a point 50 to 75 volts above the knee and
where the slope per 100 volts is less than 2.5%. This ensures that minor changes in high voltage
will have negligible effects on the sample count. Poor counting gas or separation of the methane
and argon in P-10 can result in a very high slope of the plateau. Upon initial system setup and
calibration the vendor determines and sets the optimum operating voltages for the system.
Thereafter, plateaus should be generated each time the counting gas is changed.
SUMMARY
This lesson addressed the measures used to minimize error and the fundamentals of binomial
statistics, as well as the application of these fundamentals in a nuclear counting environment.
Completion of the unit does not qualify the student to perform any tasks independently.
DOE-HDBK-1122-2009
Module 2.04 Dosimetry Study Guide
2.04-1
Course Title: Radiological Control Technician
Module Title: Dosimetry
Module Number: 2.04
Objectives:
2.04.01 Identify the DOE external exposure limits for general employees.
2.04.02 Identify the DOE limits established for the embryo/fetus of a declared
pregnant female general employee.
→ 2.04.03 Identify the administrative exposure control guidelines at your site,
including those for the:
a. General employee
b. Member of the public/minor
c. Incidents and emergencies
d. Embryo/fetus
→ 2.04.04 Identify the requirements for a female general employee who has notified
her employer in writing that she is pregnant.
2.04.05 Determine the theory of operation of a thermoluminescent dosimeter
(TLD).
2.04.06 Determine how a TLD reader measures the radiation dose from a TLD.
2.04.07 Identify the advantages and disadvantages of a TLD compared to a film
badge.
→ 2.04.08 Identify the types of beta-gamma TLDs used at your site.
→ 2.04.09 Identify the types of neutron TLDs used at your site.
→ 2.04.10 Determine the requirements for use of TLDs used at your site.
→ 2.04.11 Determine the principle of operation, and the types used, for the personnel
neutron dosimeters used at your site.
→ 2.04.12 Determine the principle of operation of self-reading dosimetry (SRD) used
at your site.
→ 2.04.13 Determine the principle of operation, and guidelines for use, for the
alarming dosimeters used at your site.
→ 2.04.14 List the types of bioassay monitoring methods at your site.
DOE-HDBK-1122-2009
Module 2.04 Dosimetry Study Guide
2.04-2
INTRODUCTION
Radiation dosimetry is the branch of science that attempts to quantitatively relate
specific measures made in a radiation field to chemical and/or biological changes that
the radiation would produce in a target. Dosimetry is essential for quantifying the
incidence of various biological changes as a function of the amount of radiation
received (dose-effect relationships), for comparing different experiments, for
monitoring the radiation exposure of individuals, and for surveillance of the
environment.
Section 29
External dosimetry is the science dealing with the measurement of a radiation field
incident to the body and the evaluation of the equivalent dose resulting from energy
deposited within the body by radiation. External dose is usually a derived or inferred
quantity since it is not possible to directly measure the exact dose to any organ or
tissue. Any measurement must be compared to a known quantity to derive dose and
equivalent dose. This process is called "calibration".
Internal dosimetry is the analysis and measurement of radionuclides in humans or
bioassay samples and the evaluation of intakes and doses from those measurements. It
involves evaluation of bioassay data, evaluation of the intake, distribution, retention,
and elimination of radionuclides, and evaluation of various absorbed doses and
equivalent dose quantities. Internal dosimetry is inherently indirect in nature. It is not
possible to determine the exact organ absorbed dose, equivalent dose or effective dose
in a living human being resulting from an intake of radioactive materials. Internal
dose is usually a derived or inferred quantity, obtained by evaluation of indirect
measurements and computational models. This is particularly true for alpha- and beta-
emitting radionuclides in the body which have low photon emission abundances.
Direct measurements of internalized photon-emitting radionuclides in organs also may
be difficult because of attenuation and scattering by overlying tissues.
The capability to accurately measure and analyze radioactive materials and workplace
conditions, and determine personnel radiation exposure is fundamental to the safe
conduct of radiological operations. Accordingly, DOE shall ensure radiological
measurements, analyses, worker monitoring results and estimates of public exposures
are accurate and appropriately made. 10 CFR 835 prescribes the requirements for
both external and internal dose monitoring.
It is the responsibility of all workers to wear personnel monitoring devices where
required by Radiological Work Permits, signs, procedures or by radiological control
personnel. They are also expected to report immediately the loss, damage or
unexpected exposure of personnel monitoring devices or off-scale readings of self-
reading dosimeters to the Radiological Control Organization (RCO). All employees
are expected to keep track of their radiation exposure status and avoid exceeding
radiological Administrative Control Levels. Additionally, all should notify the RCO
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of off-site occupational radiation exposures so that worker dosimetry records can be
updated.
References:
1. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
2. ANL-88-26 (1988) "Operational Health Physics Training"; Moe, Harold;
Argonne National Laboratory, Chicago.
3. "DOE Radiological Control Standard"; U.S. Department of Energy, 2008.
4. 10 CFR Part 835 (2007) "Occupational Radiation Protection".
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DOSIMETRY TERMS
Absorbed Dose (D):
Energy absorbed by matter from ionizing radiation per unit mass of irradiated material
at the place of interest in that material. The absorbed dose is expressed in units of rad
(or gray) (1 rad = 0.01 gray).
Section 30
Equivalent Dose (HT):
The product of average absorbed dose (DT,R) in rad (or gray) in a tissue or organ (T)
and a radiation (R) weighting factor (wR). For external dose, the equivalent dose to
the whole body is assessed at a depth of 1 cm in tissue; the equivalent dose to the lens
of the eye is assessed at a depth of 0.3 cm in tissue, and the equivalent dose to the
extremity and skin is assessed at a depth of 0.007 cm in tissue. Equivalent dose is
expressed in units of rem (or Sv).
Whole Body:
For the purposes of external exposure, head, trunk (including male gonads), arms
above and including the elbow, or legs above and including the knee.
Extremity:
Hands and arms below the elbow or feet and legs below the knee.
Committed Equivalent Dose (HT,50):
The equivalent dose calculated to be received by a tissue or organ over a 50-year
period after the intake of a radionuclide into the body. It does not include
contributions from radiation sources external to the body. Committed equivalent dose
is expressed in units of rem (or Sv).
Radiation Weighting Factor (wR ):
A modifying factor used to calculate the equivalent dose from the average tissue or
organ absorbed dose; the absorbed dose (expressed in rad or gray) is multiplied by the
appropriate radiation weighting factor. The radiation weighting factors to be used for
determining equivalent dose in rem are as follows:
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Table 1. RADIATION WEIGHTING FACTORS, wR
Type and energy range Radiation weighting factor
Photons, electrons and muons, all energies
1
Neutrons, energy < 10 keV2, 3
5
Neutrons, energy 10 keV to 100 keV2, 3
10
Neutrons, energy > 100 keV to 2 MeV2, 3
20
Neutrons, energy > 2 MeV to 20 MeV2, 3
10
Neutrons, energy > 20 MeV2, 3
5
Protons, other than recoil protons,
energy > 2 MeV
5
Alpha particles, fission fragments, heavy
nuclei
20
1. All values relate to the radiation incident on the body or, for internal sources,
emitted from the source.
2. When spectral data are insufficient to identify the energy of the neutrons, a
radiation weighting factor of 20 shall be used.
3. When spectral data are sufficient to identify the energy of the neutrons, the
following equation may be used to determine a neutron radiation weighting factor
value:
wR = 5 + 17 exp
⎥
⎦
⎤
⎢
⎣
⎡−
6
))2(ln( 2
nE
Where En is the neutron energy in MeV.
Committed Effective Dose (E50):
The sum of the committed equivalent doses to various tissues or organs in the body
(HT,50), each multiplied by the appropriate tissue weighting factor (wT)--that is, E50 =
ΣwTHT,50 + wRemainderHRemainder,50. Where wRemainder is the tissue weighting factor
assigned to the remainder organs and tissues and HRemainder,50 is the committed
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equivalent dose to the remainder organs and tissues. Committed effective dose is
expressed in units of rem (or Sv).
Total Effective Dose (TED):
The sum of the effective dose (for external exposures) and the Committed Effective
Dose (for internal exposures).
Annual Limit on Intake (ALI):
Section 31
The derived limit for the amount of radioactive material taken into the body of an
adult worker by inhalation or ingestion in a year. ALI is the smaller value of intake of
a given radionuclide in a year by the reference man (ICRP Publication 23) that would
result in a committed effective dose of 5 rems (0.05 sieverts (Sv)) (1 rem = 0.01 Sv) or
a committed equivalent dose of 50 rems (0.5 Sv) to any individual organ or tissue.
ALI values for intake by ingestion and inhalation of selected radionuclides are based
on International Commission on Radiological Protection Publication 68, Dose
Coefficients for Intakes of Radionuclides by Workers, published July, 1994 (ISBN 0
08 042651 4).
Derived Air Concentration (DAC):
For the radionuclides listed in appendix A of this part, the airborne concentration that
equals the ALI divided by the volume of air breathed by an average worker for a
working year of 2000 hours (assuming a breathing volume of 2400 m3). For the
radionuclides listed in appendix C of this part, the air immersion DACs were
calculated for a continuous, non-shielded exposure via immersion in a semi-infinite
cloud of radioactive material. Except as noted in the footnotes to appendix A of this
part, the values are based on dose coefficients from International Commission on
Radiological Protection Publication 68, Dose Coefficients for Intakes of
Radionuclides by Workers, published July, 1994 (ISBN 0 08 042651 4) and the
associated ICRP computer program, The ICRP Database of Dose Coefficients:
Workers and Members of the Public, (ISBN 0 08 043 8768).
Bioassay:
The determination of kinds, quantities, or concentrations, and, in some cases, locations
of radioactive material in the human body, whether by direct measurement or by
analysis, and evaluation of radioactive materials excreted or removed from the human
body.
In Vivo:
A direct bioassay measurement of radioactivity in living tissue, for example, a whole
body count or chest count.
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In Vitro:
The bioassay measurement of radioactivity by means of internal representative
sampling in order to estimate the radioactivity in tissue. Examples are analysis of
urine and fecal collections.
Background:
Radiation from: naturally occurring radioactive materials which have not been
technologically enhanced, cosmic sources, global fallout as it exists in the
environment (such as from the testing of nuclear explosive devices), radon and its
progeny in concentrations or levels existing in buildings or the environment which
have not been elevated as a result of current or prior activities, and consumer products
containing nominal amounts of radioactive material or producing nominal amounts of
radiation.
Declared Pregnant Worker:
A woman who has voluntarily declared to her employer, in writing, her pregnancy for
the purpose of being subject to the occupational exposure limits to the embryo/fetus as
provided in 10 CFR 835.206. This declaration may be revoked, in writing, at any time
by the declared pregnant worker.
DOE LIMITS
Limits are the legal maximum values stated in 10 CFR 835. To exceed these values is
to violate the law. Programs must be in place to ensure that exposures to ionizing
radiation are kept below these levels. To accomplish this, Administrative Control
Levels are selected well below the regulatory limits. These control levels are usually
multi-tiered with increasing levels of authority required to approve higher
Administrative Control Levels.
Section 32
Annual dose limits are based on a calendar year (January 1st through December 31st).
For assigning internal doses received from intakes (committed equivalent dose and
committed effective dose), the total 50-year committed dose received is assigned to
the time of the intake even though the actual dose is proportionally received over the
50-year period.
2.04.01 Identify the DOE external exposure limits for occupational workers.
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General Employees
General employees are DOE employees or DOE contractors. A Radiological Worker
is a general employee whose job assignment involves operation of radiation
producing devices or working with radioactive materials, or who is likely to be
routinely occupationally exposed above 0.1 rem (0.001 sievert) per year total effective
dose.
Radiological workers from other DOE or DOE contractor facilities may receive
occupational exposure to ionizing radiation as a radiological worker if they:
• Provide a record of current Radiological Worker I or II standardized core training,
• Receive site-specific Radiological Worker I or II training at the facility where they
will be working, and
• Provide their radiation dose record or a written estimate for the current year.
Table 2 lists the various legal limits for exposure to ionizing radiation. There are four
general categories listed: whole body, lens of the eyes, extremities and
organ/tissue/skin. These limits are also covered in 10 CFR 835.208 and the
Radiological Control Standard (RCS). Exposures should be well below the limits in
this table and maintained as low as reasonably achievable.
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Table 2 - Summary of Dose Limits
TYPE OF EXPOSURE
ANNUAL
LIMIT
General Employees:
Whole body (internal + external)
Lens of Eye
Extremity (hands and arms below the elbow: feet and legs below the
knee)
Any organ or tissue (other than lens of eye) and skin
5 rem
(0.05 sievert)
15 rem
(0.15 sievert)
50 rem
(0.5 sievert)
50 rem
(0.5 sievert)
Declared Pregnant Worker
Embryo/Fetus
0.5 rem
(0.005 sievert)
Per gestation
period
Minors (under age 18) and Students
Whole body (internal + external)
Extremity/Skin
Lens of Eye
0.1 rem
(0.001 sievert)
5 rem
(0.05 sievert)
1.5 rem
(0.001 sievert)
Members of the public:
Whole body (internal + external)
0.1 rem
(0.001 sievert)
Notes:
1. Internal dose to the whole body should be calculated as committed effective dose. The
committed effective dose is the resulting dose committed to the whole body from internally
deposited radionuclides over a 50-year period after intake.
2. The annual limit of exposure to “any organ or tissue” is based on the committed does to that
organ or tissue resulting from internally deposited radionuclides over a 50-year period after
intake plus any external effective dose to that organ during the year.
3. Exposures due to background radiation, therapeutic and diagnostic medical procedures, and
participation in medical research programs should not to be included in either personnel
radiation dose records or assessment of dose against the limits in this table.
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Minors//Public
Minors are individuals less than 18 years of age. The public are defined as individuals
not occupationally exposed to radiation or radioactive materials. An individual is not
a "member of the public" during any period in which the individual receives an
occupational dose. Occupational dose is an individual's dose due to exposure to
ionizing radiation (external and internal) as a result of that individual's work
assignment. Occupational dose does not include exposure received as a medical
patient, background radiation, or participation in medical research programs. The
DOE limit for exposure to minors and the public is stated in 10 CFR 835.207 and
835.208 and are listed in Table 2.
Embryo/Fetus of Declared Pregnant Workers
After a female general employee voluntarily notifies her supervisor in writing that she
is pregnant, for the purposes of embryo/fetal dose protection, she should be considered
a declared pregnant worker. The employer should provide the option of a mutually
agreeable reassignment of work tasks, without loss of pay or promotional opportunity,
such that further occupational radiation exposure is unlikely.
For a declared pregnant worker who chooses to continue radiological work:
• The dose limit for the embryo/fetus for the entire gestation period (from conception
to birth) is 0.5 rem (0.005 sievert) {10 CFR 835.206}.
• Efforts should be made to avoid exceeding 0.05 rem (0.0005 sievert) per month to
the pregnant worker {10 CFR 835.206}.
If the dose is likely to approach 0.05 rem/month (0.0005 sievert/month), additional
dosimetry will be assigned to monitor the dose to the embryo/fetus.
If the dose to the embryo/fetus is determined to have already exceeded 0.5 rem (0.005
sievert) when a worker notifies her employer of her pregnancy, the worker should not
be assigned to tasks where additional occupational radiation exposure is likely during
the remainder of the gestation period.
2.04.02 Identify the DOE limits established for the embryo/fetus of a female
occupational worker.
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Emergency Exposures
Emergency Exposure Situations
For emergency situations, general employees could be allowed to exceed specified
dose limits. The level of exposure permitted will depend upon the severity of the
emergency situation. Exposures up to 2 times the annual dose limits could be
permitted to protect against property loss. Higher exposures, up to 5 times the annual
dose limits or greater, could be permitted to save lives and protect public health. The
potential amount of exposure to rescue personnel should be evaluated, and an
exposure objective should be established for the rescue mission.
The DOE requires that the details of any exposure in excess of the annual dose limits
be documented in the occupational exposure record of the affected employee. In
addition, the incident must be investigated and the results reported to DOE.
Departmental requirements for occurrence reporting and processing provide a
mechanism for such investigations and reports. The employee must not be allowed to
receive further exposure until approval is first obtained from the contractor
management and responsible DOE field organization. Also, the employee must
receive counseling from the appropriate health experts regarding the consequences of
receiving additional occupational exposure that year and the affected employee must
agree, before returning to radiological work.
Section 34
Operations which have been suspended as a result of a dose in excess of the limits
specified in § 835.202, except those received in accordance with § 835.204, may only
be resumed with the approval of the DOE. The operation that caused the exposure
must cease pending a finding by DOE that the conditions that caused the exposure had
been eliminated.
Planned Special Exposures
A planned special exposure may be authorized for a radiological worker to receive
doses in addition to and accounted for separately from the doses received under the
normal occupational limits specified in Sec. 835.202(a) provided that each of the
following conditions are satisfied:
1. The planned special exposure is considered only in an exceptional situation when
alternatives that might prevent a radiological worker from exceeding the limits in
835.202(a) are unavailable or impractical;
2. The contractor management (and employer, if the employer is not the contractor)
specifically requests the planned special exposure, in writing; and
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3. Joint written approval is received from the appropriate DOE Headquarters
program office and the Secretarial Officer responsible for environment, safety, and
health matters.
Prior to requesting an individual to participate in an authorized planned special
exposure, the individual's dose from all previous planned special exposures and all
doses in excess of the occupational dose limits should be determined. An individual
should not receive a planned special exposure that, in addition to these doses
determined, would result in a dose exceeding:
1. In a year, the numerical value of the dose limits established in 835.202(a); or
2. Over the individual's lifetime, five times the numerical value of the dose limits
provided in 835.202(a).
Prior to a planned special exposure, written consent should be obtained from each
individual involved. Each individual consent should include:
1. The purpose of the planned operations and procedures to be used;
2. The estimated doses and associated potential risks and specific radiological
conditions and other hazards which might be involved in performing the task: and
3. Instructions on the measures to be taken to keep the dose ALARA considering
other risks that may be present.
Records of the conduct of a planned special exposure should be maintained and a
written report submitted within 30 days after the planned special exposure to the
approving organizations. The dose from these planned special exposures is not to be
considered in controlling future occupational dose as part of the normal occupational
dose of the individual under 835.202(a).
Equivalency of Dosimetric Terms
Under certain circumstances, when an individual conducts multiple activities
involving both activities under 10 CFR 835.1(b)(1) and excluded activities, e.g.,
activities involving NRC licensed activities, it is not clear as to how to apply using
different dose coefficients and weighting factors to calculate the overall cumulative
total effective dose for workers. Accordingly DOE has stated that, for the purpose of
compliance with 10 CFR 835.1(b)(1), DOE considers the following terms to be
equivalent:
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2.04-13
Table 3 Equivalency of Dosimetric Terms
Dosimetric Term Prior to 2007
Amendment to 10 CFR 835
DOE Amended Dosimetric Term
Committed effective dose equivalent
Committed effective dose
Committed dose equivalent
Committed equivalent dose
Cumulative total effective dose equivalent
Cumulative total effective dose
Deep dose equivalent
Equivalent dose to the whole body
Dose equivalent
Equivalent dose
Effective dose equivalent
Effective dose
Lens of the eye dose equivalent
Equivalent dose to the lens of the eye
Quality factor
Radiation weighting factor
Shallow dose equivalent
Equivalent dose to the skin or
Equivalent dose to any extremity
Weighting factor
Tissue weighting factor
Total effective dose equivalent
Total effective dose
SITE ADMINISTRATIVE GUIDELINES
2.04.03 Identify the administrative exposure control guidelines at your site, including
those for the:
a. Radiation worker
b. Non-radiation worker
c. Incidents and emergencies
d. Embryo/Fetus
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Radiological Workers
(Insert site specific information here)
Non-radiation Worker
(Insert site specific information here)
Exposure from Incidents or Emergencies
(Insert site specific information here)
Embryo/Fetus of a Declared Pregnant Worker
(Insert site specific information here)
SITE EXPOSURE REQUIREMENTS FOR THE UNBORN CHILD
(Insert site specific information here)
TYPES OF DOSIMETRY
As a result of irradiation, some solid substances undergo changes in some of their
physical properties. These changes amount to storage of the energy from the
radiation. Since the energy is stored, these materials can be used for dosimeters. The
features that have been studied include:
Optical density changes
Optical density changes involve a change in the color of some types of plastics
and glass. In glass, the dose range is 103 to 106 rads (10 to 104 gray). The range
for plastics is 106 to 109 rads (104 to 107 gray). Film badges, a type of optical
density dosimetry, provides low range monitoring 10 mR to 10 R for personnel
and high range monitoring 1 R to 1,000 R for accident readings.
2.04.04 Identify the requirements for a female radiation worker who has notified her
employer in writing that she is pregnant.
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Thermoluminescence
Thermoluminescence (TL) is the ability of some materials to convert the energy
from radiation to a radiation of a different wavelength, normally in the visible
light range. There are two categories of thermoluminescence.
Fluorescence This is emission of light during or immediately after irradiation
(within fractions of a second) of the phosphor. This is not a particularly useful
reaction for TLD use.
Phosphorescence This is the emission of light after the irradiation period. The
delay time can be from a few seconds to weeks or months. This is the principle of
operation used for thermoluminescent dosimeters.
The property of thermoluminescence of some materials is the main method used
for personnel dosimeters at DOE facilities.
TLD OPERATION
TLDs use phosphorescence as their means of detection of radiation.
Section 36
Electrons in some solids can exist in two energy states, called the valence band and the
conduction band. The difference between the two bands is called the band gap.
Electrons in the conduction band or in the band gap have more energy than the valence
band electrons. Normally in a solid, no electrons exist in energy states contained in
the band gap. This is a "forbidden region."
In some materials, defects in the material exist or impurities are added that can trap
electrons in the band gap and hold them there. These trapped electrons represent
stored energy for the time that the electrons are held. (See figure 1) This energy is
given up if the electron returns to the valence band.
2.04.05 Determine the theory of operation of a thermoluminescent dosimeter (TLD).
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In most materials, this energy is given up as heat in the surrounding material, however,
in some materials a portion of energy is emitted as light photons. This property is
called luminescence. (See figure 2)
TLD READER
Heating of the TL material causes the trapped electrons to return to the valence band.
When this happens, energy is emitted in the form of visible light. The light output is
detected and measured by a photomultiplier tube and a dose is then calculated. A
typical basic TLD reader contains the following components: (See figure 3)
• Heater - raises the phosphor temperature
2.04.06 Determine how a TLD reader measures the radiation dose from a TLD.
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• Photomultiplier Tube - measures the light output
• Meter/Recorder - display and record data
A glow curve can be obtained from the heating process. The light output from TL
material is not easily interpreted. Multiple peaks result as the material is heated and
electrons trapped in "shallow" traps are released. This results in a peak as these traps
are emptied. The light output drops off as these traps are depleted. As heating
continues, the electrons in deeper traps are released. This results in additional peaks.
Usually the highest peak is used to calculate the dose. The area under the curve
represents the radiation energy deposited on the TLD. A simple glow curve is shown
in figure 4.
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After the readout is complete, the TLD is annealed at a high temperature. This process
essentially zeroes the TL material by releasing all trapped electrons. The TLD is then
ready for reuse.
ADVANTAGES AND DISADVANTAGES OF TLDs
Advantages (as compared to film dosimeter badges) includes:
• Able to measure a greater range of doses
• Doses may be easily obtained
• They can be read on site instead of being sent away for developing
• Quicker turnaround time for readout
• Reusable
2.04.07 Identify the advantages and disadvantages of a TLD compared to a film badge.
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Disadvantages
• Each dose cannot be read out more than once
• The readout process effectively "zeroes" the TLD
Section 37
SITE BETA/GAMMA TLDs
(Insert site specific material here)
SITE NEUTRON TLDs
(Insert site specific material here)
DOE EXTERNAL DOSIMETRY REQUIREMENTS
Personnel dosimetry should be provided to and used by individuals as follows:
1. General employees who are expected to receive an effective dose to any portion of
the whole body of 0.1 rem (0.001 sievert) or more in a year or an equivalent dose
to the extremities, or organs and other tissues (including lens of the eye and skin)
of 10 percent or more of the corresponding limits [835.402(a)(1)];
2. Declared pregnant workers who are expected to receive from external sources an
equivalent dose of 0.05 rem (0.0005 sievert) or more to the embryo/fetus during
the gestation period [835.402(a)(2)];
3. Occupationally exposed minors likely to receive from external sources an
effective dose in excess of 50% of the limits [835.402(a)(3)];
4. Members of the public who enter the controlled area and are likely to receive an
effective dose of 0.05 rem (0.0005 sievert) or more in a year [835.402(a)(4)]; and
5. Individuals entering a high or very high radiation area radiation area
[835.402(a)(5)].
2.04.08 Identify the types of beta-gamma TLDs used at your site.
2.04.09 Identify the types of neutron TLDs used at your site.
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Neutron dosimetry shall be provided when an individual is likely to exceed the
applicable threshold provided above due to neutron radiation [835.402(b)].
Dosimeters should be issued only to individuals knowledgeable of their proper use and
worn only by those to whom the dosimeters were issued.
To minimize the number of individuals in the dosimetry program, the issuance of
dosimeters is discouraged to other than individuals entering radiological areas where
there is a likelihood of external exposure in excess of the monitoring thresholds
established in Article 511.1 of the Radiological Control Standard. Although issuing
dosimeters to individuals who are not occupationally exposed to radiation can appear
as a conservative practice, it creates the impression that the wearers are occupationally
exposed to radiation. Implementation of an unnecessarily broad dosimetry program is
not an acceptable substitute for development of a comprehensive workplace
monitoring program.
Individuals should return dosimeters for processing as scheduled or upon request, and
should be restricted by line management from continued radiological work until
dosimeters are returned.
Individuals should wear their primary dosimeters on the chest area, on or between the
waist and the neck, or in the manner prescribed by radiological control procedures or
work authorizations.
Film dosimeters should not be worn or taken off-site unless specifically authorized by
the Radiological Control Manager or designee.
The practice at some facilities of taking thermoluminescent dosimeters (TLDs) off-site
is discouraged and should not be implemented where not in place.
Individuals should not wear dosimeters issued by their resident facilities while being
monitored by a dosimeter at another facility unless authorized by the Radiological
Control Manager or designee. Individuals should not expose their dosimeters to
security X-ray devices, excessive heat, or medical sources of radiation.
Section 38
An individual whose dosimeter is lost, damaged, or contaminated should place work
in a safe condition, immediately exit the area, and report the occurrence to the
Radiological Control Organization. Reentry of the individual into radiological areas
should not be made until a review has been conducted and management has approved
reentry.
2.04.10 Determine the requirements for use of TLDs used at your site.
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SITE REQUIREMENTS FOR USE OF TLDs
(Insert site specific material here)
SITE PERSONNEL NEUTRON DOSIMETERS
(Insert site specific material here)
POCKET AND ELECTRONIC DOSIMETERS
Pocket and electronic dosimeters are supplemental dosimeters that provide real-time
indication of exposure to radiation and assist in maintaining personnel doses less than
Administrative Control Levels.
Supplemental dosimeters shall be issued to personnel prior to entry into a High or
Very High Radiation Area [835.502(a)(2)]. Supplemental dosimeters should also be
issued when planned activities could cause an individual to exceed 50 millirem or 10
percent of a facility Administrative Control Level from external radiation in 1 work
day, whichever is greater or when required by a Radiological Work Permit. Pocket
dosimeters should be selected with the lowest range applicable (typically 0-200 mR)
for anticipated personnel exposures.
Supplemental dosimeters should be worn simultaneously with the primary dosimeter
and located on the chest area, on or between the waist and the neck.
Supplemental dosimeters should be read periodically while in use and should not be
allowed to exceed 75 percent of full scale.
Work authorized by written authorization should be stopped when supplemental
dosimeter readings indicate total exposure or rate of exposure substantially greater
than planned. The Radiological Control Organization should be consulted prior to
continuation of work.
The energy dependence of supplemental dosimeters, particularly to low-energy beta
radiation, should be considered in determining their applicability. For example, the
SRPD (shown in figure 5) has a thick case that effectively shields most betas.
Use of electronic dosimeters is encouraged for entry into High Radiation Areas or
when planned doses greater than 0.1 rem (0.001 sievert) in 1 work day are expected.
2.04.11 Determine the principle of operation, and the types used, for the personnel
neutron dosimeters used at your site.
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An electronic dosimeter provides an early warning of elevated exposure through the
use of alarm set points at specified dose rates or integrated doses.
When the dose results from the pocket or electronic dosimeters differ by more than 50
percent from the primary dosimeter result and the primary dosimeter result is greater
than 0.1 rem (0.001 sievert), an investigation should be initiated to explain the
difference.
SITE SELF-READING DOSIMETERS
(Insert site specific material here)
Self Reading Pocket Dosimeters (SRPD)
The direct reading pocket dosimeter consists of an ionization chamber sensitive to a
desired radiation; a quartz fiber electrometer to measure the charge; and a microscope
to read the fiber image off a scale (reticule). (See figure 5)
Section 39
The electrometer embodies two electrodes, one of which is a moveable quartz fiber and
the other a metal frame. When the electrometer is charged to a predetermined voltage,
the electrodes assume a calibrated separation.
2.04.12 Determine the principle of operation of self-reading dosimetry (SRD) used at
your site.
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As the dosimeter is exposed to radiation, ionization occurs in the surrounding
chamber decreasing the charge on the electrode in proportion to the exposure. The
deflection of the moveable quartz fiber electrode is projected by a light source
through an objective lens to a calibrated scale and read through a microscope
eyepiece. (See Figure 6)
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Illumination for the optical system is obtained by pointing the dosimeter at any
convenient light source. Light passes through the clear glass bottom seal to illuminate
the scale.
The bottom is sealed by a bellows containing an insulated charging pin. When
charging, the charging pin moves up to contact the electrometer closing the circuit.
Sufficient voltage is applied to recharge the system. The entire dosimeter system is
hermetically sealed in a protective barrel.
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SITE ALARMING DOSIMETRY
(Insert site specific material here)
INTERNAL DOSIMETRY REQUIREMENTS
Per 10 CFR 835: for the purpose of monitoring individual exposures to internal
radiation, internal dose evaluation programs (including routine bioassay programs)
shall be conducted for:
1. General employees who, under typical conditions, are likely to receive 0.1 rem
(0.001 sievert) or more committed effective dose from all occupational
radionuclide intakes in a year;
2. Declared pregnant workers likely to receive an intake resulting in an equivalent
dose to the embryo/fetus in excess of 10 percent of the limit (or 0.05 rem [0.0005
sievert]);
3. Occupationally exposed minors who are likely to receive a committed effective
dose in excess of 50 percent of the applicable limit (or 0.05 rem [0.0005 sievert])
from all radionuclide intakes in a year;
4. Members of the public entering a controlled area likely to receive a committed
effective dose in excess of 50 percent of the limit (or 0.05 rem [0.0005 sievert])
from all radionuclide intakes in a year.
The estimation of internal dose should be based on bioassay data rather than air
concentration values unless bioassay data are unavailable, inadequate, or internal dose
estimates based on air concentration values are demonstrated to be as or more
accurate.
Personnel should participate in follow-up bioassay monitoring when their routine
bioassay results indicate an intake in the current year with a committed effective dose
of 0.1 rem (0.001 sievert) or more.
Personnel whose routine duties may involve exposure to surface or airborne
contamination or to radionuclides readily absorbed through the skin, such as tritium,
should be considered for participation in the bioassay program.
2.04.13 Determine the principle of operation, and guidelines for use, for the alarming
dosimeters used at your site.
Section 40
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Personnel should submit bioassay samples, such as urine or fecal samples, and
participate in bioassay monitoring, such as whole body or lung counting, at the
frequency required by the bioassay program.
Personnel should be notified promptly of positive bioassay results and the results of
dose assessments and subsequent refinements. Dose assessment results should be
provided in terms of rem or mrem.
BIOASSAY ASSESSMENT METHODS
Today's technology has not produced a device that allows accurate determination of
internal exposure following the entry of radioactive materials into the body.
The method that is used to determine internal dose contributions relies on calculation
of dose to affected portions of the body based on the quantities of radioactive
materials in the body. Thus, the real problem becomes one of quantifying the amount
of material present.
Bioassay is the term that is used to describe the assessment of the quantity of
radioactive material present in the body. There are currently two types of bioassay
measurements employed in nuclear industries: in vivo and in vitro. In vivo bioassay
involves counting the living tissue, as described below. In vitro involves counting an
excreted sample, such as urine.
Bioassay programs are designed to fulfill two needs:
1) Evaluate effectiveness of contamination control practices
• Routine bioassay programs utilize submission and analysis of samples from
workers in facilities where the likelihood of intake exists
• Primarily limited to urinalysis due to ease of sample collection
• Also includes initial, routine, and termination whole body counts
2) Evaluate potential consequences of accidental inhalation or ingestion of large
quantities of radioactive materials
• Can involve all types of bioassay measurements with collection and analysis
of nasal, urine, and fecal samples.
• Whole body counts provide immediate indications for given radionuclides if
individual(s) involved are free of external contamination.
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Quantification of materials actually in the body can be affected by the availability of
measurements taken early after the incident. The elimination rate of some materials
from the body falls off as the concentration in the body falls off, or with time.
Accurate quantification of initial quantities, present, thus accurate dose assessment,
can be dependent on availability of early data.
Identification of the proper bioassay technique to use is aided by a knowledge of the
types of contamination present in a particular work area. For example, if you know
that the contamination in a facility typically includes radionuclides that cannot be
detected with in vivo measurements, then it would be obvious that collection and
measurement of urine or other samples is necessary.
If the presence of gamma emitting nuclides is identified, consider the possibility of the
presence of materials that do not decay with gamma emission. Periodic radionuclide
assessment of contamination in facilities will provide information on relative
radionuclide concentrations. Caution must be exercised in using information of this
nature. Cycles of contamination should be used as an indicator only. Remember,
fresh coolant does not have the same isotopic makeup of coolant that has decayed.
Section 41
Contamination control measures cannot be too stringent during collection, handling,
and analysis of bioassay samples. Cross-contamination can cause erroneous
assumptions and inaccurate dose assessments. If procedural guidance is not sufficient
to determine required actions, consult supervision.
In Vivo Measurements
In vivo techniques consist of direct measurements of gamma or X-radiation emanating
from the body. This method is very useful for any radionuclide which emits (or has
daughters which emit) photons of sufficient energy to escape the body. The photon
flux density must be large enough for measurement in a reasonable time period, even
though the quantity of material in the organ is very small.
This method is possible only for those radionuclides emitting penetrating radiation,
e.g., Co-60 and Cs-137 or bremsstrahlung, e.g., P-32 and Sr-90. Many radionuclides,
Na-22, Fe-59, Co-60, Zn-65, Rb-86, Sr-85, Te-132, I-131, Cs-137, Ba-140, Ce-144,
Au-198, U-235, Np-239, and Am-241 emit electromagnetic radiation of sufficient
energy to be measured by external counting. If the counter has been calibrated
previously, one may rapidly determine the identity and amount of any of these
radionuclides. Such measurements are more acceptable to the subject than the
provision of samples of excreta, although they do require him to be absent from work
during the period of measurement. Direct counting of the individual without
preparation beforehand (changing into clean clothes and external decontamination)
may give misleading results, since this method measures all gamma emitting
radionuclides in or on a subject; therefore, sensitive counts (lung) should be done
immediately after the subject washes and changes into clean clothing. Radon
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daughters that cling to body hair due to their electrostatic charge are the chief source
of bad lung counts. When this method errs, it usually does so by being too high, so
that a negative result is likely to be a reliable indication that there is no internal
contamination with gamma emitters.
In external counting, the requirement for sensitivity and energy discrimination
determines the complexity of the measuring equipment. Estimations of very small
quantities require elaborate shielding of both the sensing element and the subject,
sensitive detectors, and the best discrimination between gamma ray energies.
However, a single moderately large, well-shielded sodium iodide crystal coupled with
a multichannel analyzer can usually meet the need. This system in conjunction with a
shielded chair or moving bed, is capable of determining:
• I-131 in the thyroid gland.
• Insoluble radionuclides in the chest.
• Insoluble radionuclides in the intestine.
• Insoluble radionuclides in wounds.
These need not emit highly penetrating radiation, since much of the material may be
on or near the surface, i.e., for wounds.
Because large sodium iodide crystals do not have good collimation capabilities, it is
usually not possible to measure specific organ contents directly. In some cases, solid
state detector
(GeLi) can be used for specific organ determination. However, the decreased
sensitivity of this method limits the usefulness of these measurements. Small sodium
iodide detectors are used for determining thyroid dose.
Site In Vivo Methods
Section 42
(Insert site specific material here)
Advantages of In Vivo Measurements
• No sample required
• Results obtained quickly
• Some equipment design allows field use
• Time and manpower requirements minimized.
Disadvantages of In Vivo Measurements
2.04.14 List the types of bioassay monitoring methods at your site.
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• Limited to detection and measurement of gamma emitters
• Individual must be free of external contamination
• Long count times for identification
• Effects of background
• Complex calibration procedure and calibration equipment
• Expense
• Quantification error due to differences in tissue structure from one person to
another as compared to calibration phantom.
In Vitro Measurements
The amount of material present in the body is estimated using the amount of materials
present in excretions or secretions from the body. Samples could include urine, feces,
blood, sputum, saliva, hair, and nasal discharges. Calculation requires knowledge and
use of metabolic models which allow sample activity to be related to activity present
in the body.
Resulting dose calculations to quantify committed and effective doses are estimates.
This is due partly to use of default values for measurements that cannot be readily
made such as mass of particular organs, volumes of particular fluids, etc., in lieu of
actual values for individual involved. Remember that reference man is an average.
Another contributing factor is the difference in metabolism from one individual to
another.
Urinalysis
Indicates effectively that soluble radioactive material has been deposited in the blood
for transport to various organs. A fraction of the material is normally removed from
the blood by
the kidneys and excreted. Later, material absorbed by various organs may be released
to the blood through biological exchange processes, and then may be excreted in the
urine.
Certain compounds are determined to be insoluble because they are avidly retained in
the lung. However, they also eventually appear in the urine. Particles are removed to
the pharynx by the ciliary-mucus transport mechanism where they are swallowed,
dissipated and partially absorbed in the gastrointestinal tract for transport to the blood.
Other particles are removed by transport to the lymphatic system for subsequent
release to the blood. Other particles slowly enter into a physical or chemical state
which allows direct transport from the pulmonary region of the lung to the blood. All
three cases lead to urinary excretion of the material.
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Taking samples of urine involves two special difficulties. One is the possibility of
contamination if the sample is taken at work. The other is the problem of collecting a
sample from which can be calculated the total excretion of radionuclide per unit time,
usually per day. It is ordinarily not convenient to collect a full 24-hr sample of urine,
so it is frequently necessary to estimate the fraction this is of the relatively constant
daily urine excretion.
Section 43
One of the advantages of measuring the radionuclide content of urine is that if a
radionuclide is found in a carefully collected sample of urine, there can be no doubt
that it was in extracellular body fluids. Furthermore, under the most favorable
conditions, the amount of daily urinary excretion of radionuclide may be used directly
to calculate total body content. One of the simplest examples of practical importance
is tritium oxide which is present in the same concentration in urine as in extracellular
fluids of the body.
Almost all employees are willing to provide a limited number of urine samples;
however, prolonged urine sampling involving samples taken both at home and at work
will often meet with increasing employee resistance.
Fecal Analysis
An appreciable fraction of the particles entering the gastrointestinal tract may not be
absorbed; these appear in the feces within twenty-four hours. Thus, fecal analysis is
an excellent and relatively rapid indicator that an exposure has occurred. Fecal
analysis is particularly useful for inhaled, insoluble materials that do not appear in the
urine for weeks. For many highly insoluble materials, particles remaining in the
pulmonary system continue to reach the mucus blanket, although at a greatly reduced
rate. These particles are then transported by ciliary action to the gastrointestinal tract.
Thus, fecal analysis can also contribute to the estimate of the lung burden.
Two drawbacks to fecal analysis are: (1) there is considerable employee resistance to
provide fecal samples and (2) there is very little correlation between fecal content and
organ depositions. Thus, fecal analysis is primarily a qualitative method used only for
detecting the intake of insoluble materials and providing indication of clearance of
such materials from the lungs. Fecal sampling is normally done immediately
following an incident because correlation is best when intake times are known.
Sputum
When obtainable, sputum may contain insoluble material initially deposited in the
lung and later eliminated by ciliary action. However, clearance time for sputum is
very rapid and samples must be taken immediately after an incident.
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Saliva
May be analyzed to detect internal contamination, but the only practical case in which
saliva can be used to estimate body content is that of tritium oxide, for which urine is
the usual method.
Nasal Discharge
The presence of radionuclides in nasal discharge and nasal swabs generally gives an
indication of the deposition of the coarsest inhaled particles in the nose. Measurement
of the amounts present cannot always be used for quantitative estimation of the
amount in the body, but it can be useful in detecting significant exposures and
identifying the radionuclide involved in an accident.
Site In Vitro Methods
(Insert site specific material here)
Advantages of In Vitro Measurements
• Can be used for estimation of neutron doses using activation product
concentration in hair and blood (P32 and Na24)
• Can be used to quantify presence of materials which decay by alpha and beta
emission to allow detection and measurement with external detector systems.
Disadvantages of In Vitro Measurements
• Requires sample submission and analysis
• Time and manpower requirements
BIOASSAY SCHEDULING PROGRAM
Section 44
Contamination found in a given facility will depend on the materials that are used and
produced in the facility. Thus, the materials that internal dosimetrists are primarily
concerned with will change from one site to another as well.
Baseline/Routine/Exit Evaluations
(Insert site specific material here)
2.04.14 List the types of bioassay monitoring methods at your site.
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Special Evaluations
(Insert site specific material here)
Investigation Levels
(Insert site specific material here)
Medical Uses
(Insert site specific material here)
SUMMARY
The method of operation of dosimeters is a vital knowledge for RCT. RC personnel are
the first line of defense against abuse of these instruments and must ensure the proper
wearing and use of them.
Internal exposure involves a source (contaminant) inside the body. It is more difficult to
measure; sophisticated whole body counters or indirect measurements of excreta samples
are required to obtain an estimate. The exposure from the contaminant does not stop
when the person leaves the radiation field and the contaminant continues to irradiate
tissue all day and all night. If necessary, medical treatment is required to enhance the
removal of the source material from the body. Alpha radiation poses the biggest
problem.
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DOE-HDBK-1122-2009
Module 2.05 Contamination Control Study Guide
2.05-1
Course Title: Radiological Control Technician
Module Title: Contamination Control
Module Number: 2.05
Objectives:
2.05.01 Define the terms "removable and fixed surface contamination," state
the difference between them and list common methods used to
measure each.
2.05.02 State the components of a radiological monitoring program for
contamination control and common methods used to accomplish
them.
2.05.03 State the basic goal of a contamination control program and list
actions that contribute to its success.
2.05.04 State the basic principles of contamination control and list examples
of implementation methods.
2.05.05 List and describe the possible engineering control methods used for
contamination control.
2.05.06 State the purpose of using protective clothing in contamination areas.
2.05.07 List the basic factors which determine protective clothing
requirements for personnel protection.
INTRODUCTION
Contamination control is probably one of the most difficult and challenging tasks the
Radiological Control Technician will encounter. To have a successful contamination
control program, the radiological control staff must have considerable foresight,
initiative, and experience.
References:
1. DOE Radiological Control Standard, Articles 325, 337 and 338 (2008).
2. "The Health Physics and Radiological Health Handbook," Shleien; 1992.
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TYPES OF CONTAMINATION
Section 45
Contamination is simply defined as radioactive material in an unwanted location, e.g.,
personnel, work areas, etc. Two types of contamination are possible, fixed and
removable. Fixed contamination is radioactive surface contamination that is not easily
transferred to other personnel or equipment through normal contact. Removable
contamination is radioactive surface contamination that is easily transferred to other
personnel or equipment through normal contact.
Removable contamination is measured by a transfer test using a suitable sampling
material. Common materials used for the monitoring are the standard paper disk smear
or cloth smear. The standard technique involves wiping approximately 100 cm2 of the
surface of interest using moderate pressure. A common sampling practice used to ensure
a 100 cm2 sample is to wipe a 16 square inch "S" shape on the surface (i.e., 4 inches by 4
inches). Qualitative, large area wipe surveys may be taken using other materials, such as
Masslin cloth or Kimwipe, to indicate the presence of removable contamination. These
are commonly used when exact levels of contamination are not required.
Fixed contamination is measured by use of a direct survey technique. This technique,
commonly referred to as "frisking," indicates the total contamination on a surface
apparent to the detector from both fixed and removable. When non-removable levels are
to be recorded, the removable level must be subtracted from the total.
Appendix D to 10 CFR 835 lists contamination levels in units of dpm/100 cm2. Typical
evaluation of fixed contamination monitoring includes adjusting the portable instrument
count rate (counts per minute) to account for the area of the monitoring instrument (probe
area) and the instrument efficiency to obtain units of dpm/100 cm2.
Footnote 4 to Appendix D states that when “removable contamination on objects of
surface area less than 100 cm2 is determined, the activity per unit area shall be based on
the actual area and the entire surface shall be wiped”. For example, for an object with a
total surface area of 50 cm2, the entire object would be wiped and the count result would
be divided by the counting efficiency and multiplied by an area adjustment factor of two
(100 cm2/50 cm2) to get a result in units of dpm/100 cm2. A similar approach may be
used for fixed contamination monitoring of objects with surface area less than 100 cm2.
However, care must be taken in monitoring very small objects and the sensitivity of the
monitoring protocol should be evaluated.
2.05.01 Define the terms "removable and fixed surface contamination," state the
difference between them and list common methods used to measure each.
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ASSESSING CONTAMINATION HAZARDS
In order to acquire the radiological information necessary for contamination control, there
are several components to a radiological monitoring program. These are:
• Constant monitoring
• Area and equipment surveys
• External personnel surveys
• Personnel internal monitoring and bioassay
Constant Monitoring
There are various types of constant monitoring instruments throughout the
facilities to warn personnel of radiation and contamination hazards. Some
instruments are permanently installed, and some instruments are portable to allow
movement from place to place as deemed appropriate by the radiological control
staff.
Section 46
Continuous air monitor (CAM). These instruments continuously sample the air
for radioactive contamination in specific locations. The air being sampled is either
drawn through a moving particulate filter which is then monitored by a detector
system or through an internal detector to directly identify radioactive materials
present. A CAM can give both a visual and audible alarm to warn personnel of
the presence of airborne contamination.
Process monitoring systems. Process monitoring systems monitor certain
operations in various facilities to alert operators of abnormal conditions which
might lead to the release of excessive amounts of radioactivity to the facility or
environment.
Area and Equipment Surveys
Area and equipment surveys are conducted routinely throughout the facilities to
locate sources of radiation and contamination and to detect potential changes in
radiological conditions. Pre-job surveys are performed prior to work in
radiological areas in order to evaluate the hazards and determine work limitations
and physical safeguards.
Direct instrument surveys. Various types of portable survey instrumentation are
used to measure the presence of radioactive contamination on a floor or surface.
This is the only method available to detect "fixed" surface contamination. It must
2.05.02 State the components of a radiological monitoring program for contamination
control and common methods used to accomplish them.
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be remembered, however, that this method will detect removable as well as
"fixed" surface contamination activity. As a result, a direct survey must be
combined with a "smear" survey to determine if the surface contamination present
is removable or fixed.
Smear surveys. A disk smear is wiped over an area of 100 square centimeters
and counted with proper instrumentation to determine the activity of the nuclides
present. Contamination levels are specified in units of dpm/100 cm2 after applying
applicable instrument correction factors. For objects less than 100 cm2, the units
are reported as dpm/object area. Disk smears are small so they are usually used in
an area of suspected contamination. Properly applied experience will dictate to
the surveyor where contamination is most likely to occur and hence those areas
that should be surveyed with disk smears. Disk smears are required if
contamination levels are to be quantified.
Many routine contamination surveys are taken in areas not suspected to be
contaminated with a chemically treated cloth called a masslinn (paper towel,
atomic swipe, etc). The cloth is lightly pushed over an area and scanned with an
appropriate detector to detect the presence of contamination. If contamination is
detected, a more thorough disk smear survey should be performed. These large
area wipes are used only as an indication of removable surface contamination.
External Personnel Surveys
Personnel surveys are either performed by the individual (self-monitoring) using
hand-held or automated instruments or by a radiological control technician. Self-
monitoring is typically performed upon exiting a contaminated area at established
boundary points. Personnel monitoring by a RCT is usually conducted whenever
contamination of the body or clothing is suspected, or as required by exit
monitoring when self-monitoring is not feasible (remote location) or not allowed.
The types of hand-held or automated instruments used for self-monitoring are
generically described below.
Section 47
Personnel monitors. Portable instruments (friskers) with sensitive hand held
detectors are used by personnel to identify contamination on themselves whenever
contamination is suspected. These monitors are used whenever exiting
contaminated areas, Radiological Buffer Areas, and in some cases Radiological
Control Areas (RCA). Geiger-Mueller (GM) detectors are most often used for
beta-gamma monitoring and scintillation detectors for alpha monitoring.
Personnel Contamination Monitors (PCM). The PCM provides personnel with
an external whole body monitoring system. The contamination detectors within
the monitors are capable of performing a survey of the whole body in a period of
a few seconds, dependent upon background radiation levels present in the area
and the personnel contamination limit of concern. These automated systems
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typically provide a more reliable method of locating personnel contamination over
hand-held instruments.
Hand and Foot Monitors. Hand and foot monitors with detachable hand-held
detectors provide another alternative to using hand-held instruments (friskers).
These devices can monitor the hands and feet during a period of a few seconds,
again, dependent upon background radiation levels present in the area and the
personnel contamination limit of concern. After the hands and feet have been
monitored, the detachable hand held detectors, which are typically of a larger
detector size, can be used to monitor the remainder of the body in a shorter time
period than most friskers.
Portal monitors. The portal monitor is a "door frame" type device which
provides a final monitoring point to ensure contamination is not spread outside the
facility to other facilities or the general public. These types of monitors are
typically used only for beta-gamma monitoring.
Personnel surveys. Personnel surveys are performed whenever contamination of
the body or clothing is suspected, or as required for exit monitoring, e.g., when
friskers or automated monitoring instruments are not available.
The whole body should be surveyed with special attention to areas which are
more likely to become contaminated. Contamination of the feet (shoes) would
indicate removable surface contamination on the floor just traversed. The hands
are extremely prone to becoming contaminated when working directly with
radioactive materials. Upon completion of work or prior to leaving the area for
glovebox, laboratory fume hood, sample station, or localized benchtop operations,
a minimum survey of hands, arms, and front portions of the body must be
performed.
Other body areas which are prone to contamination are the buttocks, knees, and
elbows and head.
The nose and mouth should be surveyed upon discovery of any level of facial skin
contamination, or if airborne contamination was detected in the workplace, since
contamination in this area might indicate the need for bioassay sampling. The
nose can be swabbed with Q-tips and the swab counted in a smear counter to
determine a potential deposition. Contamination of the nose or mouth may
indicate airborne contamination.
All open wounds must be monitored since contaminants can be readily absorbed
into the body.
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Section 48
In addition to these specific body areas, the surveyor should pay special attention
to any area of the body and/or clothing which he or she suspects might be
contaminated.
Upon detecting personnel contamination, follow-up area and/or equipment
surveys may be necessary to determine the source of contamination and the extent
the contamination has spread, if any.
Personnel Internal Monitoring
A routine program of internal contamination monitoring is conducted as a final
check on contamination control procedures. This program consists of external
whole/partial body counting and/or urinalysis.
In-vivo Bioassay: The individual is placed inside a array of very sensitive
detectors to measure the activity and energies of gamma ray emissions from
inside the body. This information can be used to determine the amount and
identify the type of nuclides present. Examples include whole body, lung, or
scanning bed counters.
In-vitro Bioassay: Urine or feces samples are collected from an individual to
determine the type and activity of the nuclides present in bodily waste. This
information is used to approximate the amount of nuclides present in the body by
their calculated rate of elimination. This method can be used to assess the
presence of non-gamma emitting nuclides.
BASIC GOAL OF CONTAMINATION CONTROL
Once the presence of radioactive material has been located, the basic goal underlying any
effective contamination control program is to minimize contaminated areas and maintain
contamination levels as low as reasonably achievable.
In some situations, this is not always possible due to:
• Economical conditions: Cost of time and labor to decontaminate a location(s)
out-weighs the hazards of the contamination present.
2.05.03 State the basic goal of a contamination control program and list actions that
contribute to its success.
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• Radiological conditions: Radiation dose rates or other radiological conditions
present hazards which far exceed the benefits of decontamination.
• Operating conditions: Some areas, e.g., hot cells, will be contaminated due to
normal operations.
Other means of control must be initiated when decontamination is not possible.
Engineering control (ventilation and containment), administrative procedures (RWPs),
and personnel protective equipment are alternatives for the control of contamination. In
Fixed Contamination Areas the contamination may be covered by paint, floor tiles, etc.
when decontamination is not possible.
"Good Housekeeping" is a prime factor in an effective contamination control program. It
involves the interactions of all groups within the facility. Each individual must be
dedicated to keeping "his house clean" to control the spread of contamination. Every
possible effort should be made in all operations to confine the spread of radioactive
materials to the smallest possible area. A sound preventive and corrective maintenance
program can prevent many radioactive material releases. All material taken into or out of
contaminated areas must be controlled. RCTs should always be alert for potential
violations to the basic principles of contamination control.
• Use of improper contamination control methods
• Bad work practices
• Basic rule or procedure violations
• Radioactive material releases or liquid spills
CONTAMINATION CONTROL MEASURES
Section 49
Controlling the spread of contamination is probably the most difficult and challenging
task the Radiological Control Technician will encounter. To have a successful
contamination control program, the radiological control staff must have considerable
foresight, initiative, and experience. The radiological control staff will assist line
management with the basic principles of contamination control.
• Access/Administrative Controls
• Engineering Controls
• Personnel Protective Measures
• Decontamination
• Preventive Methods
2.05.04 State the basic principles of contamination control and list examples of
implementation methods.
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Access/Administrative Controls
Once contamination has been located and quantified and radiological areas have
been determined, access control to these areas must be adequately established.
Two basic access control points, primary and secondary, are used in
contamination control.
The primary access control point in a facility is the entry and exit portal between
the clean area and the radiologically controlled area or Radiological Buffer Area.
The success of a control program is based on controlling the movement of
personnel and equipment between these areas to prevent release of contamination
to a clean location.
The secondary access control points (perhaps the most important) are set up
within the Radiological Buffer Areas (RBAs) to control access between surface
contaminated areas and non-contaminated areas. Yellow and magenta rope,
chain, tape or similar barriers are used to identify the boundaries and provide a
recognizable visual barrier to personnel. In areas of ongoing work activities,
special requirements will always be established for entry and exit through these
access control points. When the radiological conditions are severe, the access
control point may be continuously manned by a Radiological Control Technician.
It is not expected that Radiological Buffer Areas will be established around
inactive or secured Contamination Areas.
Step-off pads (SOPs) identify the entry and exit points to contaminated areas
when possible. The use of SOPs creates a sharp line of distinction between the
surface contamination area and the clean areas. Proper procedures must be
established and observed for crossing the SOP to prevent the spread of
contamination. All tools and/or equipment used in a surface contamination area
which are unmonitored should be placed in clean plastic bags or securely wrapped
in plastic before being removed from the area. All personnel and materials
exiting the area should be monitored to ensure they are free of contamination.
Radiological Buffer Areas should also be established in areas where there is a
need to limit exposure to external radiation, such as Radiation, High Radiation,
and Very High Radiation Areas. The boundary should be established to limit
radiation dose to general employees to less than 100 mrem per year. RBAs need
not be posted for external exposure control if other posted boundaries provide
equivalent employee protection.
Other administrative controls used for contamination control include the use of
Radiological Work Permits, routine workplace surveys that are performed in
order to detect trends in the potential buildup of workplace contamination, and
DOE-HDBK-1122-2009
Section 50
Module 2.05 Contamination Control Study Guide
2.05-9
review of operational and maintenance procedures to ensure radiological
requirements are incorporated in the daily conduct of operations.
ENGINEERING CONTROLS
Ventilation. The design of permanent or temporary ventilation systems needs to
be such that air flow is from clean areas to RCAs, to areas of moderate
contamination, to areas of high contamination, and finally to an exhaust system
capable of removing any contamination from the air. Slight negative pressure is
typically maintained in buildings/rooms where potential contamination exists. As
necessary, high efficiency particulate air (HEPA) filters are used to remove
radioactive particles from the air.
Containment. On jobs with very high contamination potential, a plastic tent
(greenhouse or hut) can be built around the work area to confine all contamination
to as small an area as possible. A portable ventilation exhaust system (such as
HEPAs) may be used to control air flow in the work area and remove airborne
contamination. Where possible, small containment devices, such as glove boxes,
glove bags, or hoods can be used to contain the contamination depending on the
nature and location of the work being performed. Drums or other approved
containers are also utilized.
Bagging. The most widely used method of containment is bagging or wrapping.
Contaminated tools or equipment are placed in plastic bags, or securely wrapped
in plastic, before being moved outside a contaminated area. When possible,
wrapping tools or equipment prior to entry can help control contamination during
use inside the contaminated area.
Design and Control. Design of facilities should be such that efficiency of
maintenance, operations, and decontamination is maximized. Components should
be selected that minimize the buildup of radioactivity. Support facilities are to be
included that provides for donning and doffing of protective clothing and for
personnel monitoring. Personnel traffic should be routed away from
contaminated areas.
PERSONNEL PROTECTIVE MEASURES
2.05.05 List and describe the possible engineering control methods used for
contamination control.
2.05.06 State the purpose of using protective clothing in contamination areas.
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If engineering control methods are not adequate, then personnel protective measures,
such as protective clothing and respiratory equipment, will be used. The purpose of
protective clothing is to keep contamination off the skin and clothing of the workers.
Protective clothing allows personnel to work inside a contaminated area with removable
contamination and to exit the area without spreading contamination to uncontrolled areas.
The use of protective clothing alone will not guarantee complete elimination of personnel
contamination and is not a substitute for implementing proper controls, but if used
properly, protective clothing will afford a high degree of protection.
All personnel entering contaminated areas with removable contamination will be required
to wear certain items of protective clothing. The types of clothing required will vary
depending upon the contamination levels and the nature of the work to be performed.
Some additional factors for the selection of protective clothing include the type and form
of contamination; potential for increased levels of contamination, area of the body at risk,
and competing hazards, i.e., heat stress, asbestos, etc.
Section 51
Some type of respiratory protective equipment will be required for work in areas where
very high contamination levels exist or airborne contamination is present.
Decontamination
Line management is responsible for ensuring prompt decontamination, where
practical, of facilities, tools, material, and equipment so that contamination can be
minimized in the workplace. Reasonable efforts should be directed toward the
decontamination and unconditional release of these items rather than their
disposal as radioactive waste. Only items that are extremely contaminated with
risks during decontamination that out-weighs the benefit to be gained for reuse
should be considered for disposal.
Preventive Methods
The following are practical methods used for the prevention/control of
contamination:
• Identify and repair leaks before they become a serious problem.
• Establish adequate work controls before starting jobs.
• While conducting pre-job briefs, discuss measures that will help reduce or
prevent contamination spread.
• Change out gloves or protective gear as necessary to prevent cross-
contamination of equipment.
• Pre-stage areas to prevent contamination spread from work activities.
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• Cover piping/equipment below a work area to prevent dripping
contamination onto less contaminated areas.
• Cover/tape tools or equipment used during the job to minimize
decontamination after the job.
• Follow good work practices such as good housekeeping and cleaning up
after jobs.
• Confine the spread of radioactive material releases by a sound preventive
maintenance program.
• Control and minimize all material taken into or out of contaminated areas.
BASIS FOR ESTABLISHING PROTECTIVE CLOTHING REQUIREMENTS
In order to prevent radioactive contamination from getting on or into the body, protective
clothing requirements must be established where the potential exists.
There are several basic factors which determine the type and extent of protective clothing
required:
• type and form of contamination
• levels of contamination
• type of work being performed
Some additional factors to consider include the potential for increased levels of
contamination, the area of the body at risk, and competing hazards, i.e., heat stress,
asbestos, etc. Once the types of protection needed are established, the most efficient
protective clothing must be selected from the different articles of protective clothing
available for use.
A discussion of the controls/clothing types for specific areas of the body follows.
2.05.07 List the basic factors which determine protective clothing requirements for
personnel protection.
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Whole body protection
A lab coat provides protection from low levels of contamination and is only
applicable when the potential for upper body contact with contaminated surfaces
is very low. In general, lab coats are worn for hands-off tours and inspections in
areas with removable contamination at levels 1 to 10 times the values in Table 2-2
of the Radiological Control Standard, or during benchtop, laboratory fume hood,
sample station, and glovebox operations.
Section 52
Coveralls provide protection from low to moderate levels of DRY contamination
protection. Protection is low when body contact with contaminated surfaces is
prolonged (since contamination can be ground into or through the cloth) and when
the surface is wet. The degree of protection can be increased by use of more than
one pair at a time to protect the body. Cloth coveralls are permeable, and so are
not effective against radionuclides with high permeability properties (gases,
tritium, etc.).
Plastics coveralls provide protection from high levels of dry contamination and
wet contamination. They provide limited protection from tritium and other highly
permeating radionuclides (which may be transported through coveralls to the skin
surface).
Disposable coveralls, e.g., tyvek suits, provides moderate protection from
radioactive contamination and are used for work involving mixed hazards, i.e.,
asbestos, PCBs, etc., where reuse is not desirable. Disposable coveralls can be
fairly easily torn.
It should be noted that at a minimum, outer personal clothing should not be worn
under protective clothing for entry into High Contamination Areas or during work
conditions requiring a double set of protective clothing. Sites may choose to be
more restrictive as necessary to minimize potential skin/clothing contamination.
Hand protection
Surgical gloves are a minimal requirement normally used in only light
contamination work areas which require a high degree of dexterity. Surgical
gloves are fairly easily torn or punctured.
Rubber gloves are lightweight and provide a good gripping surface. They are
normally used in moderate to heavy contamination locations. Rubber gloves have
greater puncture, abrasion and solvent resistance, but afford a lower degree of
dexterity than surgical gloves.
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Neoprene gloves are synthetic rubber gloves mounted to various containment
devices to allow access by the wearer into the device. They are used to provide
protection for the wearer when working inside a containment device in which
highly contaminated materials are present. They are usually of arm length
attached to dry boxes, glove boxes and bags, or other cabinets and provide a gas
tight seal to the structure. Gloves are normally taped to the sleeve of the lab coat,
coveralls, plastic suit, etc. and are tabbed to permit easy removal.
Cotton glove liners may be worn inside standard gloves for comfort, but should
not be worn alone or considered as a layer of protection.
Leather or canvas work gloves should be worn in lieu of or in addition to standard
gloves for work activities requiring additional strength or abrasion resistance.
Foot protection
Booties are used to protect the lower leg area below the coveralls from
contamination. Different constructions used are plastic and cloth (sometimes
called cloth shoe covers).
Shoe covers are worn over booties to provide a second layer of protection and
provide traction to wearer. They are normally constructed of plastic or rubber,
and may be taped to the pant legs of the coveralls or plastic suit depending on the
level of contamination and type of job.
Respiratory protection
Full face masks are used to filter particulate radionuclides and/or radioactive
iodine from the breathing air of the wearer when the surrounding atmosphere is
not immediately dangerous to the life and health of the wearer.
Section 53
Supplied air systems may prevent inhalation of particulate and gaseous nuclides
by the wearer in a non-life threatening atmosphere.
A self contained breathing apparatus (SCBA) is used to provide a portable source
of breathing air to the user when entering an atmosphere which may be
immediately dangerous to life and health.
Medical approval, training, and fit testing are required prior to respiratory
protection use. Systems should be in place to verify these criteria in the field. To
ensure proper use of a respirator prior to entering areas requiring its use, the
wearer should be clean shaven in the area of fit and he/she should perform fit
checks of their respirators to ensure a proper seal.
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FACILITY PROTECTIVE CLOTHING REQUIREMENTS
(Insert facility specific material here)
SUMMARY
All reasonable efforts must be made to control contamination in order to provide
protection for workers on site and the general public from the hazards presented by
radioactive material. This lesson covered the phases of a contamination monitoring
program, and the goal, principles, and methods used to support the contamination control
program.
DOE-HDBK-1122-2009
Module 2.06 Air Sampling Program/Methods Study Guide
2.06-1
Course Title: Radiological Control Technician
Module Title: Air Sampling Program/Methods
Module Number: 2.06
Objectives:
2.06.01 State the primary objectives of an air monitoring program.
2.06.02 Describe the three physical states of airborne radioactive
contaminants.
2.06.03 List and describe the primary considerations to ensure a representative
air sample is obtained.
2.06.04 Define the term "isokinetic sampling" as associated with airborne
radioactivity sampling.
2.06.05 Identify the six general methods for obtaining samples or
measurements of airborne radioactivity concentrations and describe
the principle of operation for each method.
a. Filtration
b. Volumetric
c. Impaction/impingement
d. Adsorption
e. Condensation/dehumidification
f. In-line/flow-through detection
2.06.06 Describe the general considerations for selection of an air monitoring
method.
2.06.07 State the purpose of the five primary types of airborne radioactivity
samplers/monitors:
a. Personal air samplers (breathing zone)
b. High volume/flow rate air samplers
c. Low volume/flow rate air samplers
d. Portable continuous air monitors
e. Installed continuous air monitoring systems
2.06.08 List the factors that affect the accuracy of airborne radioactivity
measurements and describe how these factors affect sample accuracy.
→ 2.06.09 Describe the site air monitoring program that includes monitoring
frequencies, calculational methods, applicable derived air
concentration limits, and methods for determining radon interference.
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INTRODUCTION
Inhalation of radioactive particles is the largest cause of internal dose. Airborne
radioactivity measurements are necessary to ensure that the control measures are
effective and continue to be effective. Regulations govern the allowable dose to
an individual. The total effective dose is determined by combining the external
and internal effective dose values. Typically, airborne radioactivity levels are
maintained well below allowable levels to keep the total dose small.
Section 54
References:
1. "Introduction to Health Physics"; Cember, Herman; 4nd
ed.; McGraw-Hill Medical; 2008.
2. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
3. Moe Harold, Operational Health Physics Training, ANL-88-26,
Department of Energy, Argonne National Laboratory, Chicago, 1988.
4. "Air Monitoring", Chapter 10 of Implementation Guide for Use with 10
CFR 835, "Occupational Radiation Protection".
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INTRODUCTORY KNOWLEDGE
In order to understand the "allowable effective dose values", you must have a
basic understanding of the Annual Limit on Intake (ALI), and Derived Air
Concentration (DAC). (Refer to RCT lesson 1.12 sections 3 to 8).
Annual Limit on Intake (ALI) - The quantity of a single radionuclide which, if
inhaled or ingested in one year, would irradiate a person, represented by reference
man (ICRP Publication 23), to the limiting value for control of occupational
exposure.
Derived Air Concentration (DAC) - The concentration of a radionuclide in air
that, if breathed over a period of a work year, would result in the ALI for that
radionuclide being reached. The DAC is obtained by dividing the ALI by the
volume of air breathed by an average worker during a working year (2400 m3).
The DAC is the average airborne concentration that a radiation worker may be
exposed to for 40 hours/week, 50 weeks/year. When continuously exposed to this
concentration, the resultant dose is either a committed effective dose of 5 rem or a
committed equivalent dose to an organ or tissue of 50 rem (whichever one is more
limiting). Since the DAC is a time-average concentration, as the concentration
increases, the exposure time must decrease in order to maintain exposure below
the ALI. This means that one could be exposed to concentrations significantly
above the DAC for short periods of time and still be below the annual limit on
intake, or ALI.
Example 2.06-1
The DOE, in 10 CFR 835, has set a DAC for tritium gas of 200 mCi/m3, and a DAC for HTO
of 20 μCi/m3. Notice that the DAC for tritium gas is 10,000 times higher than the DAC for
HTO.
HTO 20 μCi/m3
T2 (gas) 200,000 μCi/m3
Exercise: Calculate the dose a worker would receive if he was exposed to 300 mCi/m3 of
tritium gas for 30 minutes.
Exercise: Calculate the dose a worker would receive if he was exposed to 300 mCi/m3 of
HTO for 30 minutes.
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PURPOSE AND OBJECTIVES OF AIRBORNE RADIOACTIVITY SAMPLING
Airborne radioactive contaminants are of concern to the radiological control
organization due to the biological effects of the ionizing radiation emitted by
those contaminants. The inhalation of radioactive airborne particles is one of the
most important routes of entry of radionuclides into the human body. This
represents a relatively complicated process that depends on particle size
distribution of the airborne particles, their dynamical behavior in air, and the
physical and chemical properties of the particles that control the radionuclide
biokinetics after deposition in the respiratory tract. Air monitoring is performed
to identify and monitor airborne radioactive material in order to control the intake
of airborne radioactive material by workers.
Section 55
Regulations govern the allowable or limiting effective doses to an individual. The
total effective dose of an individual is determined by combining the external and
internal effective dose values. Typically, airborne radioactivity levels are
maintained well below allowable levels to keep the internal effective dose
contribution to the total effective dose small. Confirmation that airborne
radioactivity levels are maintained low is accomplished by the airborne
radioactivity sampling program. It is important to note that the individual
equivalent dose from internal sources is not normally determined from air
sampling analysis data, unless other information, such as bioassay data, is
unavailable, inadequate, or internal dose estimates based on air concentration
values are demonstrated to be as or more accurate.
It is necessary to be aware that the air monitoring program is only one element of
a comprehensive radiation protection program. Individuals involved with the air
monitoring program should interact with personnel working in other elements of
the radiation protection program, particularly with individuals involved in
contamination control and internal dosimetry.
The primary objectives of an air monitoring program are:
• to measure the concentration of the radioactive contaminant(s) in the air
by collection and analysis
• to identify the type and physical characteristics of the radioactive
contaminant
• to help evaluate the hazard potential to the worker
• to evaluate the performance of airborne radioactivity control measures
2.06.01 State the primary objectives of an air monitoring program.
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• to assess air concentration data in order to determine if bioassay sampling
should be initiated to verify whether an exposure has occurred, and if so,
to determine the magnitude of the exposure
Allowable concentration values, such as derived air concentrations (DAC) are
used as an index of the degree of control needed and achieved. Documented
measurements of the airborne radioactivity concentrations are required to
demonstrate that satisfactory control is achieved and maintained.
Additionally, the air monitoring program must demonstrate that airborne
radioactivity released to the general environment is maintained as low as
reasonably achievable and below the allowable limits established by regulatory
agencies.
The primary goal of the air monitoring program is to determine if the level of
protection provided to the worker is sufficient to minimize the internal equivalent
dose. Allowable concentration values, such as derived air concentrations (DACs),
are used as an index of the degree of control needed and achieved. Documented
measurements of the airborne radioactivity concentrations are required to
demonstrate that satisfactory control is achieved and maintained.
Air sampling is required where an individual is likely to receive an exposure of 40
or more DAC-hours in a year. Other situations requiring sampling are:
• to establish the need for posting of airborne radioactivity areas and to
determine the need for respiratory protection of workers
• to assess unknown hazards during maintenance on systems contaminated
with radioactive material or when there is a loss of process controls
• to assist in determining the type and frequency of bioassay measurements
needed for a worker
Section 56
• to provide an estimate of worker exposures for situations where bioassay
measurements may not be available or their validity is questionable
• to develop baseline airborne radioactivity levels and verify containment
integrity as necessary during startup of a new facility or new operation
within an existing facility
• where respiratory protection devices for protection against airborne
radionuclides have been required
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• real-time air monitoring shall be performed as necessary to detect and
provide warning of airborne radioactivity concentrations that warrant
immediate action to terminate inhalation of airborne radioactive material
THE NATURE OF AIRBORNE RADIOACTIVITY
Airborne radioactive contaminants are generally divided into three categories,
based on the physical state of the contaminant.
• Particulates
• Gases
• Vapors
The physical properties of airborne radioactive particles can affect inhalation
deposition, their dynamical properties in air, and particle solubility in the lung.
Particulates
Particulate contaminants are solid and liquid particles, ranging upward from
molecular sizes (approximately 10-3 um), suspended in the air. Solids may be
subdivided into fumes, dusts, and smokes, which are distinguished mainly by their
mode of generation. Liquids are subdivided into mists and fogs, depending on the
dispersion of the liquid particulates. The term "aerosols" is used to collectively
refer to relatively stable suspensions of either solid or liquid particles in a gaseous
medium. Generally, particulates are more readily retained in the lungs than are
gases, but retention of particulates is highly dependent on particle size and
solubility in the lung. While this suggests that particulate airborne contaminant
sampling should measure particle size, this is not practically accomplished on a
routine basis. Certain sampling instruments utilize the characteristics of particle
size to separate larger particles from smaller particles (e.g., impactors). This is an
important factor in that the size range of particles retained in the respiratory tract
is generally 1-10 μm.
The retention of inhaled radioactive particles after deposition in the pulmonary
region of the lung is strongly influenced by the dissolution characteristics of the
particles. Dissolution in the lungs allows clearance into the blood and the rest of
the systemic circulation. For this reason the various absorption types of
radioactive particles are classified with respect to their potential solubility in the
lungs. Specifically, these are:
2.06.02 Describe the three physical states of airborne radioactive contaminants.
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• Type S for the very insoluble particle that takes years to clear from the
lungs
• Type M for the somewhat more soluble particles that take weeks to
dissolve and clear into the systemic circulation
• Type F for the relatively soluble particles that dissolve in a matter of days
in the lung
Gases
Gases are substances that, under normal conditions of temperature and pressure,
exist in the gaseous phase. The retention of the gases in the body from inhalation
is poor so radioactive gases are usually treated as an external source of exposure.
Radioactive gases typically found are the fission product gases, such as xenon and
krypton, and naturally occurring radon. While the gases contribute primarily to
external exposure, the particulate daughters to which they decay can contribute to
internal exposure.
Section 57
Vapors
Vapors are considered the gaseous phase of a substance that is normally a solid or
liquid under normal conditions of temperature and pressure. Airborne vapor
sampling is most commonly done for radioiodine and tritium. The contaminant
may be dispersed in vapor form at abnormal conditions of temperature and
pressure. However, as the temperature and pressure conditions return to
"normal," the contaminant will return to its normal solid or liquid form, or
become a particulate. Sampling methods for vapors should isolate or measure the
contaminant regardless of whether the vapor or particulate form is present.
REPRESENTATIVE AIR SAMPLES
To ensure that the sample is representative of the actual conditions:
• The airborne radioactivity concentration entering the sample line must be
representative of the airborne radioactivity concentration in the air near the
sampling device.
• The airborne radioactivity concentration entering the sampling inlet must
be representative of the airborne radioactivity concentration at the point of
concern, or the air that is breathed, i.e., breathing zone.
2.06.03 List the primary considerations to ensure a representative air sample is
obtained.
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When obtaining an air sample, care must be taken to ensure that the sample obtained is
representative of the air around the sampling device. This is particularly important for
sample lines that directly sample an air flow, such as a stack or duct monitor. Air flow
into sampling lines needs to be balanced with respect to the flow of air around the probe
or sample inlet. If there is not a relative balance between these velocities, particles may
be thrown in or out of a
sampling probe rather than being sampled in a representative fashion. To ensure the
sample is representative, the flow rate in the sample line or inlet must be the same as the
flow rate in the system, such as the duct or stack.
When the sample line velocity is equal to the system velocity at the sample point, it is
called isokinetic sampling.
If the velocities are not the same, or isokinetic, then discrimination can occur for
smaller or larger particles. This occurs because the inertia of the more massive
particles prevents them from following an airstream that makes an abrupt
directional change.
2.06.03 List the primary considerations to ensure a representative air sample is
obtained.
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If the velocity of the sample airstream is > the velocity of the system airstream,
then the larger particles can not make the abrupt change and are discriminated
against in the sample, i.e., the smaller particles are collected more efficiently.
If the velocity of the sample airstream is < the velocity of the system airstream,
then the small particles do make the abrupt change and are discriminated against
in the sample, i.e., the larger particles are collected more efficiently.
To minimize particle losses, sampling lines should be as short (less than six feet
preferred) and straight as possible to avoid sample deposition along the walls of
the tube. When possible, sample lines should be vertical instead of horizontal to
prevent gravimetric settling of large particles. Additionally, the sampling line
should have no more than one bend and be made of conducting material.
Section 58
There are other factors to consider for maximizing the efficiency of airborne
radioactivity detection. Self-absorption losses, e.g., dust loading, should be
minimized. This is especially critical for alpha radiation detection. Air in-
leakage between the sample intake and the sample collection medium should be
eliminated to the greatest degree possible by instrument design. Finally, the
system and mechanisms within the instrument for sample collection should be
designed and constructed to minimize deterioration and to facilitate
decontamination. This is more critical in areas with corrosive atmospheres.
When obtaining an air sample, care must be taken to ensure that the sample
obtained is representative of the air at the point of interest (the breathing zone).
Depending on the source of the airborne contaminant, the concentrations within a
work area can vary over several orders of magnitude. The sample taken should be
representative of the air entering the nose and mouth of the individual workers
since the data obtained may be used to estimate potential worker intakes.
Obviously, the best sampling method then is to sample the air at the individual's
nose and mouth. This sampling method may not always be practical and general
work area sampling may be the alternative. Care must be exercised in the
selection of the number and placement of the general area air samplers to ensure
that the sample is as representative as possible.
BASIC SAMPLING METHODS
Basically, three types of samples are collected:
1. A volumetric sample in which part of the atmosphere is isolated in a
suitable container, providing the original concentration of the contaminant
at a particular place and time.
2. An integrated sample which concentrates the contaminant on some
collecting medium, providing an average concentration over the collection
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time. (Sometimes called a "grab" sample if collected in a short period of
time.)
3. A continuous sample where the sample air flow is directed past or through
a detection device providing a measurement of the activity per unit
volume of air.
Breathing zone air monitoring should be performed continuously in areas where
workers are likely to exceed 40 DAC-hr exposure in a year. Breathing zone air
monitoring is used to identify possible worker internal exposures and the need for
follow-up bioassay measurements.
Source specific air sampling is performed near an actual, or likely, release point in
a work area. This is typically used to verify containment or confinement
integrity, documenting airborne radioactivity levels, and providing guidance on
personnel protective measures (e.g., determining when respiratory protection is
required).
Grab air sampling is used for temporary or nonroutine (e.g., emergency response)
situations and as a backup for other types of air sampling in the event of
equipment failure. Portable air sampling equipment is typically used for
operations requiring a grab sample. Sample flow rates may vary depending upon
the specific application, but should always allow collection of a sample volume
adequate to ensure the minimum detectable activity of the sampling and counting
system is no greater than 2% of an ALI.
There are six general methods for obtaining samples or measurements of airborne
radioactivity concentrations.
Section 59
• Filtration
• Volumetric
• Impaction/impingement
• Adsorption
2.06.05 Identify the six general methods for obtaining samples or measurements of
airborne radioactivity concentrations and describe the principle of operation
for each method.
a. Filtration
b. Volumetric
c. Impaction/impingement
d. Adsorption
e. Condensation/dehumidification
f. In-line/flow-through detection
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• Condensation/ dehumidification
• In-line/flow-through detection
Filtration
Filter samplers employ filtration of the air as the method of concentrating the
airborne radioactive particulate (aerosol) contaminants. Filtration is the most
common sampling method employed for particulates because it is relatively
simple and efficient, but is ineffective as a sampling method for gases and vapors.
The filter sampling technique employs an air mover, such as a vacuum pump, to
draw air through a removable filter medium at a known flow rate for a known
length of time.
• If the flow rate and sample time are known, the total volume collected can
be calculated.
• After analysis of the filter medium to determine the amount of radioactive
material collected on the filter at the time of the sample, the airborne
concentration can also be calculated.
The filtration medium selected for a sample depends on several factors: the
collection efficiency required, the flow resistance of the medium, the mechanical
strength of the filter, pore size, the area of the filter, the background radioactive
material of the filter, cost, self-absorption within the filter, and chemical
solubility. A wide choice of filters is available.
The most common types are:
• Cellulose-asbestos filters
• Glass fiber filters
• Membrane filters are manufactured with various pore sizes and can be
dissolved in organic solvents and analyzed in a counter, e.g., a liquid
scintillation counter.
Filter samples are evaluated by direct radiation counting or by radiochemical
assay. Filters may be mounted into different types of holders including those with
open faces for direct sampling and those with in-line enclosure for sampling
through a sampling hose, with sample air flow drawn through a flow meter with a
suitable air pump.
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Volumetric
Volumetric samplers employ a sample container into which the sample is drawn,
by some method, and isolated for analysis. Several methods are employed to
draw the sample into the container.
• The container may be evacuated by a vacuum pump and isolated away
from the sample location. The container is opened at the sample location
to draw the air into the container. The sample is sealed in the container
and removed for analysis.
• An air mover, such as a vacuum pump, may be employed at the sample
location to draw a representative atmospheric sample into the container.
• The container could be filled with water, isolated and taken to the sample
location. The water is poured out of the container, drawing the air sample
into the container as the water pours out.
This method can be employed for particulates, gases, and vapors.
Impaction/Impingement
Section 60
Impingers or impactors concentrate particulate contaminants on a prepared
surface by abruptly changing the direction of the sample air flow at some point in
the sampler. Particles are collected on a selected surface as the airstream is
sharply deflected. Due to their inertia, the particles are unable to follow abrupt
changes in airstream direction. The surface on which the particles are collected
must be able to trap the particles and retain them after impaction. Several
methods are commonly used to trap the particles, such as:
• Coating the collection surface with a thin layer of grease or adhesive.
• Immersing the collection surface in a fluid, such as water or alcohol. The
liquid is then analyzed after the sample is collected.
Impingers and impactors may utilize several stages or impingement distances to
discriminate for or against different particle sizes. Impactors are frequently used
to isolate particles larger than the undesired smaller particles, such as transuranics
over radon daughters, or radon daughters over fission products.
Adsorption
Adsorber sampling devices concentrate the contaminants by causing them to
adhere to the surface of the adsorption medium. Adsorption is the adhesion of a
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substance to the surface of another substance through chemical bonding. The
adsorption medium is granulated or porous to increase the surface area available
for trapping of the contaminant. The technique employs an air mover to draw and
collect the sample through the adsorption media. Adsorbers, such as activated
charcoal, silica gel, and silver zeolite, are commonly used to collect organic
vapors and non-reactive gases and vapors. Some uses of each type are:
• Activated charcoal is used primarily for radioiodine sampling, but does
trap noble gases, such as xenon, krypton and argon.
• Silica gel is primarily used for tritium oxide vapor sampling.
• Silver zeolite is used for radioiodine sampling when trapped noble gases
would interfere with the radioiodine analysis.
Particulates would be "filtered" by the adsorption media and must be filtered out
before the adsorption process to prevent interference during the analysis of the
media.
Condensation/Dehumidification
Condensation or dehumidifier sampling devices employ a "cold trap" to condense
water vapors in the sampled atmosphere and provide a liquid sample for further
analysis. Some means, such as liquid nitrogen or a refrigeration unit is utilized to
cool the condensation surface and cause condensation of the water vapor as it
passes over the cold surface. The collected water is frequently analyzed using a
liquid scintillation counter. Calculations must include the relative humidity and
temperature of the air at the time the sample is taken to determine the
concentration of water vapor per unit volume of air. This technique is normally
only applied for sampling tritium oxide vapor (HTO or T2O).
In-Line/Flow Through Detection
In-line or flow-through samplers employ an air mover to direct the sample air
flow through or past the detection device. This method is employed for
radionuclides which are difficult to collect or detect by other means. Because the
air flow passes directly outside the detector or actually through the inside of the
detector, the air must be filtered for particulates or vapors that could accumulate
on or in the detector. In-line detectors are used to measure gaseous activity after
filtration and adsorption have been accomplished. Flow-through detectors are
employed for radionuclides, such as tritium, which emit low-energy radiation, that
could not otherwise pass through the detector window.
Section 61
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Multi-Purpose Samplers and Monitors
The various sampling methods described above may be combined into one
sampler or monitor. Some samplers employ the filtration method for particulates,
the adsorption method for vapors and the volumetric grab-sample method for
gases (in that order). Some advantages of combining these methods are:
• One vacuum pump supplies the air flow for all the samples.
• All the samples are drawn at the same time to minimize the amount of
time spent by the technician drawing samples.
In addition, some monitors have detectors installed to monitor each sample and
provide an immediate readout as well as other capabilities, such as alarms, data
records, process controls, and trending.
SELECTION OF THE AIR SAMPLING METHOD
It is critical that the proper air sampling method and equipment be selected
because:
• The data obtained must be meaningful and accurate to adequately assign
radiological control measures
• Improper selection and use may incorrectly indicate a safe environment
where an airborne radiological hazard exists or leads to unneeded postings
where no hazard exists.
The general considerations for the selection of an air sampling method includes
several factors.
• The environmental conditions in the area where the sample is to be
obtained. Humid conditions may preclude the use of some methods, such
as paper filtration devices or charcoal canisters, because water vapor
loading of the medium will
change the collection efficiency and flow rate. High temperature
environments may cause some samplers to overheat if run for long periods
of time. Explosive gases may be present which could present an explosion
hazard for samplers with electric motors not designed for such
environments. Dusty areas could cause excessive sample loading which
2.06.06 Describe the general considerations for selection of an air monitoring method.
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will reduce sampler flow rates and potentially overheat the sampler.
Corrosive environments may lead to the deterioration of the sampling
device.
• The physical characteristics of the area in which the sample is to be
obtained. An electrical outlet may not be available or close, and a battery
powered sampler would be better suited. Close spaces or passages may
preclude the use of movable CAMs or heavy samplers.
• The energy and type of radiation of the radionuclide being monitored.
This will dictate the type of CAM or analysis equipment required to
determine the airborne radioactivity concentration.
• The expected concentration level. This will determine the length of
sample time and type of sampler required. Low-level concentrations will
require large volumes to reduce statistical errors and meet minimum
sensitivity levels of the analysis equipment. Large volume samples
obtained over a long time period are best obtained by samplers designed to
run for long periods. If immediate readout of information is needed, then
collection and analysis are done at the same time. If not, then samples
may be taken and removed to a central analysis location.
• The physical state of the airborne contaminant. Dependent upon whether
the contaminant is either gas, vapor or aerosol, will dictate the type of
sampler and sample medium that is required.
Section 62
• The type of survey required. Specific methods, such as breathing zone
samples, routine general area samples, general work area samples, general
area trending over time, etc., also determines the type of equipment that is
selected.
• Procedural requirements. This may dictate a particular type of sample
method and/or sample medium for a given application. Prior to selection,
one should check the appropriate procedures and ask supervision and
experienced technicians for their input.
2.06.07 State the purpose of the five primary types of airborne radioactivity
samplers/monitors:
a. Personal air samplers (breathing zone)
b. High volume/flow rate air samplers
c. Low volume/flow rate air samplers
d. Portable continuous air monitors
e. Installed continuous air monitoring systems.
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PRIMARY TYPES OF AIR SAMPLERS
The five primary types of airborne radioactivity samplers/monitors are:
• Personal air samplers (breathing zone)
• High volume/flow rate air samplers
• Low volume/flow rate air samplers
• Portable continuous air monitors (CAMs)
• Installed continuous air monitoring systems
Personal Air Samplers
Personal air samplers (PAS) provide an estimate of the airborne radioactivity
concentration in the air the worker is breathing during the sampling period. PAS
may also be used to determine if the protection factor for respiratory equipment is
exceeded, to compare with other workplace air samples, and to verify the
effectiveness of engineered and administrative controls.
PAS are small, portable battery-powered devices which sample the air in the
breathing zone of the worker's environment, making allowances to eliminate
interferences the samplers themselves may have on a worker's activities. Some
characteristics are:
• The device contains a small battery-powered pump that is calibrated to a
flow rate approximately 1/10 (2 liters per minute) the breathing rate of a
worker performing light activity.
• The sampling line terminates in a filter cassette which contains the
filtration medium for the radioactive particulate contaminants.
• The sample filter cassette is attached close to the nose and mouth of the
individual.
High Volume/Flow Rate Samplers
High volume/flow rate samplers provide an estimate of the airborne radioactivity
concentration at a particular location in a short period of time. Portable high flow
rate samplers are used to collect airborne aerosols on a filter paper (filtration) or
on a greased planchet (impaction). Portable high flow rate samplers can also be
used to collect radioiodine samples using activated charcoal cartridges
(adsorption) as long as the maximum flow rate of the cartridge is not exceeded or
a correction factor is used. These samplers do not have installed detectors and the
sample must be removed from the sampler and analyzed on separate analysis
equipment. The high volume/flow rate samplers may be used to:
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• Provide a routine "slice of time" estimate of the general area airborne
radioactivity
• Verify boundaries of areas posted for airborne radioactivity
• Monitor the airborne radioactivity related to a specific work activity
Section 63
High volume samplers typically use flow rates of at least 10 cubic feet per minute
(cfm). Although these samplers are noisy and not intended for continuous duty,
the shorter sample times allow for greater sensitivity.
Low Volume/Flow Rate Samplers
Low volume/flow rate samplers provide an estimate of airborne radioactivity
concentrations averaged over a longer period of time at a particular location.
Portable low volume/flow rate samplers are used to collect samples for aerosols
on filter paper (filtration) and radioiodine on an adsorption medium, such as an
activated charcoal cartridge. Low volume/flow rate samplers may be used to
provide average airborne radioactivity estimates over a period of time for:
• Commonly traversed areas that normally have a low probability of
airborne radioactivity problems
• Areas not commonly traversed with a higher probability of airborne
radioactivity problems
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• Backup samples in areas where airborne radioactivity problems are
discovered by other means
• Work maintenance activities normally characterized by low airborne
radioactivity concentrations.
Low volume samplers generally have flow rates set at approximately 20 lpm, the
breathing rate of a worker performing light activity. Although these samplers
must run
longer for reasonable sensitivity, they are generally quiet and can be used for
continuous duty.
Portable Continuous Air Monitors
Portable continuous air monitors (CAMs) provide an estimate of airborne
radioactivity concentrations averaged over time at a particular location, and
provide immediate readout and alarm capabilities for preset concentrations.
These air monitors are portable low flow rate (20 lpm) sampling systems,
containing the necessary sampling devices and built-in detection systems to
monitor the activity on the filters, cartridges, planchettes and/or chambers in the
system. The system may provide a visual readout device for each type of sample
medium, a recording system for data, and computer functions such as data
trending, preset audible and visual alarms/warning levels and alerts for system
malfunctions. Typical CAMs provide information on alpha and/or beta/gamma
particulates (filtration), radioiodine activity (adsorption) and noble gas activity
(volumetric chamber or in-line detector).
Portable CAMs can be utilized as:
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• Low volume general area samplers
• Monitors with alarm capabilities for areas where airborne radioactivity
conditions may quickly degrade
• Trending devices in selected areas
• Devices to locate system leaks, if used with the appropriate length hose or
tubing.
Installed Continuous Air Monitors
Installed continuous air monitoring systems (CAMs) provide an estimate of
airborne radioactivity concentrations averaged over time at a fixed, designated
location, and provide immediate local and remote readout and alarm capabilities
for preset concentrations. These air monitors are fixed low flow rate sampling
systems, and contain the necessary sampling devices and built-in detection
systems to monitor the activity of selected areas or airstreams. The system may
provide a local and remote visual readout device, a recording system for data, and
computer functions such as data trending, preset audible and visual
alarms/warning levels and alerts for system malfunctions. Installed CAM
applications include:
Section 64
• Fixed installations capable of sampling several locations through valved
sample lines
• Stack monitors
• Duct monitors
Factors affecting the accuracy of airborne radioactivity measurements include:
• Sample is not representative of the atmosphere being sampled
• Sample is not representative of the air being breathed by the worker
• Incorrect or improperly installed sampling media for the selected sampler,
causing leak or improper flow rates
• Malfunctioning, miss-operated, or miscalibrated sampling device, causing
errors in flow rate measurements
2.06.08 List the factors that affect the accuracy of airborne radioactivity measurements.
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• Accuracy and operation of the timing device, causing errors in the time
value
• Accuracy and operation of the flow rate measuring device, causing errors
in the flow rate value
• Mishandling of the sample media causing cross-contamination or removal
of sample material
• Changes in the collection efficiency of the medium due to sample loading,
humidity and other factors
• Improper use or selection of analysis equipment
• Inherent errors in the counting process due to sample geometry, self-
absorption, resolving time, backscatter and statistical variations
• Mathematical errors during calculations due to rounding of numbers and
simple mistakes
• Incorrect marking of samples and inaccurate recording of data
It is important that the personnel performing the sample collection and analysis
minimize the magnitude of these errors to ensure that accurate and reliable data is
obtained for the assignment of internal exposure control methods.
BASIC AIR SAMPLE CALCULATIONS
Once the air sample is collected and analyzed, calculations must be performed to
determine the amount of activity per unit volume.
The specific calculations for particular sampling methods are not covered in this
lesson; however, some basics are necessary for each calculation.
The analysis of the sample provides the activity of the sample at the time of the
sample analysis. This value may be corrected for decay for the time period
between when the sample was taken to when it was analyzed.
• This is especially true for short-lived radionuclides.
• This correction may not be necessary for very long-lived radionuclides.
The volume of the sample must be determined from the sample data recorded,
such as flow rates at the beginning and end of the sample, and sample time period.
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The basic calculation listed would also include the conversions necessary for the
desired units such as dpm/liter to μCi/cc.
The calculation would also include correction factors, as necessary, for:
• Interference of other radionuclides, such as radon and thoron daughters
• Collection efficiency
• Counter efficiency
• Self-absorption by the sample media
• Counter background
• Temperature and pressure as applied to flow rate
Many errors are inherent or induced in the sampling analysis process and affect
the accuracy of the resulting data. The operator of the sampling and analysis
equipment must be aware of these points of error to ensure the resulting data is as
accurate as possible. Quality assurance that is applied to all phases of the air
monitoring program will minimize many errors.
Section 65
(Insert site specific material here)
SUMMARY
This lesson has addressed the primary objectives of an airborne radioactivity
monitoring program, the physical states of the airborne contaminants,
representative air sampling, the general sampling methods, the factors affecting
the accuracy of sample collection and analysis, the primary types of samplers, and
the proper selection of the air sampling method.
2.06.09 Describe the site air monitoring program that includes monitoring frequencies,
calculational methods, applicable derived air concentration limits, and methods for
determining radon interference.
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EXAMPLE SOLUTIONS
2.06-1
Exercise: Calculate the dose a worker would receive if he was exposed to 300 mCi/m3
of tritium gas for 30 minutes.
Solution: 1 DAC of tritium gas is 200 mCi/m3, so 300 mCi/m3 is 1.5 DAC. 1.5 DAC for
0.5 hours (30 min.) is .75 DAC-hours. One DAC-hr is 2.5 mrem, so .75 DAC-hr is .75 x
2.5, or ~ 1.9 mrem.
Exercise: Calculate the dose a worker would receive if he was exposed to 300 mCi/m3
of HTO for 30 minutes.
Solution: 1 DAC is 20 μCi/m3, so 300 mCi/m3 is 15,000 DAC for 0.5 hours (30 min.)
which is 7,5000 DAC-hours. One DAC-hr is 2.5 mrem, so 7,500 DAC-hrs is 7,500 x 2.5,
or 18,750 mrem, or 18.75 rem.
Key Points: Compare the dose received from HTO to the dose received from exposure
to the same concentration of tritium gas in the previous exercise. The dose received for
this exposure is 10,000 times worse.
Compare the DACs for tritium and plutonium. For Pu-239 the DAC (Absorption Type
M) is given in 10CFR835 as 5E-12 mCi/mL or 2E-1 Bq/m3. List the reasons that
inhaling plutonium is more hazardous than tritium.
Confirmation that airborne radioactivity levels are maintained low is accomplished by the
airborne radioactivity sampling program. The individual equivalent dose from internal
sources is not normally determined from air sampling analysis data, unless bioassay data
are unavailable.
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DOE-HDBK-1122-2009
Module 2.07 Respiratory Protection Study Guide
2.07-1
Course Title: Radiological Control Technician
Module Title: Respiratory Protection
Module Number: 2.07
Objectives:
2.07.01 Explain the purpose of respiratory protection standards and
regulations.
2.07.02 Identify the OSHA, ANSI, and DOE respiratory protection program
requirements.
2.07.03 Identify the standards which regulate respiratory protection.
2.07.04 Describe the advantages and disadvantages (limitations) of each of the
following respirators:
a. Air purifying, particulate removing filter respirators
b. Air purifying, Chemical Cartridge and Canister respirators for
Gases and Vapors
c. Full-face, supplied-air respirators
d. Self-contained breathing apparatus (SCBA)
e. Combination atmosphere supplying respirators
2.07.05 Define the term protection factor (PF).
2.07.06 State the difference between a qualitative and quantitative fit test.
2.07.07 State the recommended physical functions the subject must perform
during a respirator fit test.
2.07.08 State how the term protection factor (PF) is applied to the selection of
respiratory protection equipment.
Section 66
2.07.09 State the general considerations and considerations for the nature of
the hazard when selecting the proper respiratory protection equipment.
→ 2.07.10 Identify the types of respiratory equipment available for use at your
site.
2.07.11 Identify the quality specification breathing air must meet.
References:
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2.07-2
1. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
2. "Introduction to Health Physics"; Cember, Herman; 4nd ed.; McGraw-Hill
Medical; 2008.
3. "Limits for Inhalation of Radon Daughters by Workers", ICRP Publication
32.
4. "Operational Health Physics Training Course", Moe, H.J., et. al., Argonne
National Laboratory, Argonne, 88-26.
5. "Radiation Detection and Measurement", Knoll, G., John Wiley and Sons,
New York, 2000.
6. 10 CFR 835, "Occupational Radiation Protection", 2007.
7. "Practices of Respiratory Protection", ANSI Z88.2, 1992.
8. "Manual of Respiratory Protection Against Airborne Radioactive
Material",NUREG-0041, 1976.
9. Respiratory Protection, Federal OSHA, 29 CFR 1910, 134.
10. DOE-STD-1167-2003, DOE Respiratory Acceptance Program for
Supplied-Air Suits.
11. CGA G7.1-1989, Breathing Air, Commodity Specification for Air
12. 10 CFR 851, “Worker Protection Programs”, 2007.
13. DOE Order 440.1B (2007), Worker Protection Management for DOE
(including National Nuclear Security Administration) Federal Employees.
14. ANSI Z88.2 (1992).
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OSHA AND DOE REQUIREMENTS
10 CFR 851, for contractors, and DOE Order 440.1, for Federal employees,
mandates the requirements for a respiratory protection program contained in 29
CFR 1910.134 and ANSI Z88.2.
The Occupational Safety and Health Standard, 29 CFR, Part 1910.134, specifies
the minimal acceptable respiratory protection program must contain or address the
following:
• Written standard operating procedures and program governing the
selection and use of respirators shall be established.
• Respirators shall be selected on the basis of hazards to which the worker is
exposed.
• The user shall be instructed and trained in the proper use of respirators and
their limitations.
• Respirators shall be regularly cleaned and disinfected. Those issued for
the exclusive use of one worker should be cleaned after each day's use, or
more often if necessary. Those used by more than one worker shall be
thoroughly cleaned and disinfected after each use.
• Respirators shall be stored in a convenient, clean, and sanitary location.
• Respirators used routinely shall be inspected during cleaning. Worn or
deteriorated parts shall be replaced. Respirators for emergency use such
as self-contained devices shall be thoroughly inspected at least once a
month and after each use.
• Appropriate surveillance of worker area conditions and degree of
employee exposure or stress shall be maintained.
• There shall be regular inspection and evaluation to determine the
continued effectiveness of the program.
2.07.01 Explain the purpose of respiratory protection standards and regulations.
2.07.02 Identify the OSHA, ANSI, and DOE respiratory protection program
requirements.
2.07.03 Identify the standards which regulate respiratory protection.
Section 67
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• Persons should not be assigned to tasks requiring use of respirators unless
it has been determined that they are physically able to perform the work
and use the equipment. The health care provider shall determine what
health and physical conditions are pertinent. The respirator user's medical
status should be reviewed periodically (for instance, annually).
• NIOSH approved or accepted respirators shall be used. The respirator
furnished shall provide adequate respiratory protection against the
particular hazard for which it is designed in accordance with standards
established by competent authorities.
These form the basis for any occupational safety respiratory protection program.
ANSI Z88.2-1992 further specifies the minimal acceptable program for industries
involved in the use of radioactive material, and addresses the following:
• Individual exposures limited by both inhalation and skin absorption
• Air sampling and bioassays
• Engineering controls as the primary method
• Individuals exposed to greater than the specified DAC or other exposure
limits
• Respiratory protection equipment approvals (NIOSH)
If allowance for the use of respiratory protection equipment in estimating
radiation exposures is made, then the following must be observed:
• The protection factor must be sufficient to limit the annual internal dose
considering the anticipated peak exposure concentration and associated
DAC.
• If the exposure is later found to be greater than estimated, the corrected
value shall be used, if less than estimated, the corrected value may be
used.
• Surveys and bioassays conducted as appropriate to evaluate actual
exposures.
• Written procedures for selection, fitting, maintenance, records, issuance
and pre-use operability checks of respirators, and supervision and training
of personnel using respirators must be established.
• Prior to initial use and annually, determination by a qualified health care
professional of a user's physical capability to wear a respirator must be
performed.
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• A written policy statement on use of engineering controls instead of
respirators; routine, non-routine, and emergency use of respirators; and
periods of respirator use and relief from respirator use must be issued.
• Each user must be advised that they can leave the work area upon failure
of equipment, physical distress or deterioration of operating conditions.
• Equipment is to be used for appropriate environment and special
equipment such as visual or communication devices are to be issued when
needed.
• Emergency use equipment must be specifically certified as such by
NIOSH.
RESPIRATORY PROTECTION EQUIPMENT
Air Purifying, Chemical Cartridge and Canister Respirators for Gases and Vapors
Description:
Vapor and gas-removing respirators use cartridges or canisters containing
chemicals (i.e., sorbents) to trap or react with specific vapors and gases and
remove them from the air breathed. The basic difference between a cartridge and
a canister is the volume of the sorbent.
Limitations:
These respirators do not provide oxygen, so they must NEVER be worn in oxygen
deficient atmospheres.
Section 68
Unless specifically approved by DOE, no credit may be taken for the use of
sorbent cartridges or canisters for protection against radioactive gases and vapors.
High humidity environments may shorten the life of the sorbent material.
2.07.04 Describe the advantages and disadvantages (limitations) of each of the following
respirators:
b. Air purifying, Chemical Cartridge and Canister respirators for Gases and Vapors
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Atmosphere Supplying Respirators - Air Line
Description:
Air line respirators use a central source of breathing air that is delivered to the
wearer through an air supply line or hose. The respirator type is either a tight-
fitting facepiece (half face or full) or loose-fitting hood/suit. There are essentially
two major groups of air line respirators - the air-line device and the hose mask
with or without a blower. Hose masks are not used in power reactors;
consequently, further discussion will be limited to demand, pressure demand, and
continuous flow air line respirators.
In a demand device, the air enters the facepiece only on "demand" of the wearer,
i.e., when the person inhales. During inhalation, there is a negative pressure in
the mask, so if there is leakage, contaminated air may enter the mask and be
inhaled by the wearer. For this reason, demand respirators are generally no longer
used. The pressure demand device has a regulator and valve design such that
there is a flow (until a fixed static pressure is attained) of air into the facepiece at
all times, regardless of the "demand" of the user. The airflow into the mask
creates a positive pressure. The continuous-flow air line respirator maintains a
constant airflow at all times and does not use a regulator, but uses an airflow
control valve or orifice which regulates the flow of air. The continuous-flow
device does not guarantee a positive pressure in the facepiece.
Limitations:
Since the air line respirator provides no protection if the air supply fails, they shall
not be used in IDLH atmospheres or for emergency escape or rescue.
The trailing air supply hose severely limits mobility so it may be unsuitable if
frequent movement among separated work stations is required.
The length of hose, number of potential users, and pressure of the supply system
can reduce the number of allowable users. Control of the air quality is essential to
avoid introduction of hazardous respiratory agents to the wearers breathing zone.
"Bubble suits" can aspirate air into the suit when the wearer lifts his arms.
Consequently, the suit must be tested for the exact conditions of use.
2.07.04 Describe the advantages and disadvantages (limitations) of each of the following
respirators:
c. Full-face, supplied-air respirator
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Special Considerations:
Requirements for use of respirators in "dangerous" atmospheres is specified in
29 CFR 1910.134(e)(3) as follows:
“(3) Written procedures shall be prepared covering safe use of respirators
in dangerous atmospheres that might be encountered in normal operations
or in emergencies. Personnel shall be familiar with these procedures and
the available respirators.
Section 69
(i) In areas where the wearer, with failure of the respirator, could be
overcome by a toxic or oxygen-deficient atmosphere, at least one
additional man shall be present. Communications (visual, voice, or signal
line) shall be maintained between both or all individuals present. Planning
shall be such that one individual will be unaffected by any likely incident
and have the proper rescue equipment to be able to assist the other(s) in
case of emergency.
(ii) When self-contained breathing apparatus or hose masks with flowers
are used in atmospheres immediately dangerous to life or health, standby
men must be present with suitable rescue equipment.
(iii) Persons using air line respirators in atmospheres immediately
hazardous to life or health shall be equipped with safety harnesses and
safety lines for lifting or removing persons from hazardous atmospheres or
other equivalent provisions for the rescue of persons from hazardous
atmospheres shall be used. A standby man or men with suitable self-
contained breathing apparatus shall be at the nearest fresh air base for
emergency rescue."
Manufacturers of airline respirators include instructions specifying a range of air
required to produce at least the minimum required flow rates (4 CFM for tight
fitting facepiece and 6 CFM for hoods). These specifications are based on hose
lengths and the number of sections connected together. Determining if the proper
air flow rate is achieved can be complicated by the use of a breathing air manifold
supplying more than one user. The following are recommendations which should
be considered.
If all the hose lengths and number of hose fittings are the same, then a manifold
with a single regulator and pressure gauge is appropriate for ensuring the proper
pressure is used. (Note: If the pressure is within the manufacturer's
specifications, then the delivery air flow rate should be at least 4 CFM for tight
fitting respirators and 6 CFM for hoods).
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For situations where each user has different hose lengths, different number of
connection or different air pressure requirements then a separate pressure gauge
should be used as follows:
The air flow rate should be measured at the end of the breathing tube (i.e., at the
delivery end). This air flow rate should be measured using a calibrated rotameter
or equivalent air flow measuring device.
To utilize the Protection Factor (PF) assigned to air supplied hoods, a delivery
flow rate of at least 6 CFM but not greater than 15 CFM must be obtained. The
individual user's air flow valves should not be altered to maintain a minimum
delivery flow rate of 6 CFM as this violates the NIOSH/MSHA approval. Taping
or otherwise securing the airflow valves in the fully open position does not void
the NIOSH/MSHA approval provided the valve is not permanently altered or
made so that it would be impossible to increase or decrease the air flow by the
user.
Atmosphere Supplying Respirators - Self-Contained Breathing Apparatus (SCBA)
Description:
The self-contained breathing apparatus (SCBA) allows the user to carry a
respirable breathing supply does not need a stationary air source such as a
compressor to provide breathable air. The air supply may last from 3 minutes to 4
hours depending on the nature of the device.
There are two groups of SCBAs - the closed circuit and the open circuit.
Section 70
Another name for closed circuit SCBAs is "rebreathing" device. The air is
rebreathed after the exhaled carbon dioxide has been removed and the oxygen
content restored by a compressed oxygen source or an oxygen-generating solid.
These devices are designed primarily for 1-4 hours use in toxic atmospheres.
An open circuit SCBA exhausts the exhaled air to the atmosphere instead of
recirculating it. A tank of compressed air carried on the back, supplies air via a
regulator to the facepiece. Because there is no recirculation of air, the service life
of the open circuit SCBA is shorter than the closed circuit system. The only type
of open circuit SCBA available for use is “pressure demand”.
2.07.04 Describe the advantages and disadvantages (limitations) of each of the following
respirators:
d. Self-contained breathing apparatus (SCBA)
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The pressure demand open circuit SCBA has a regulator and a valve design which
maintains a positive pressure in the facepiece at all times regardless of the
"demand" of the user. Because of the high degree of protection provided by the
pressure-demand SCBA, this type of unit is recommended for emergency use,
escape and rescue. There
also exist combination atmosphere supplying respirators which utilize supplied air
and an SCBA.
Combination Atmosphere Supplying Respirators
Two types of combination supplying respirators are the combination pressure
demand breathing apparatus and the dual purpose breathing apparatus. The
combination pressure demand breathing apparatus provides respiratory protection
for personnel who must work in atmospheres that are immediately dangerous to
life or health (IDLH). When connected to a respirable air source, the device
permits the wearer to work and move about freely, within the limits of the
approved hose length. The combination pressure demand breathing apparatus is
equipped with a small air cylinder which enables the wearer to escape from
dangerous atmospheres in case the primary air supply is interrupted.
The apparatus serves as a long duration work device and as an escape device as
well. It is approved for respiratory protection for entry into, for extended periods
of work in, and for escape from IDLH atmospheres. If used for entry into IDLH
atmospheres, the air line must be connected before entry. The self-contained air
supply is approved for escape only.
Operation of the combination pressure demand breathing apparatus is manual. It
is an approved, rated 5-minute escape device. The pressure demand air line
respirator phase is connected by an approved air-supply hose to a primary
respirable air source; the worker breathes from this source with the valve of the
egress (exit) cylinder of the device turned off until the user is ready to leave the
working area. If the primary air supply source should fail for any reason, the
worker can switch to the egress cylinder by turning a valve and escape to a safe
atmosphere. The worker then can leave, connected to the primary air source, or
can open the egress cylinder valve and have approximately five minutes'
respiratory protection. When breathing from the air cylinder, the user can remain
connected to the primary air supply and exit, or can disconnect from the air source
for easier escape.
2.07.04 Describe the advantages and disadvantages (limitations) of each of the following
respirators:
Section 71
e. Combination atmosphere supplying respirators.
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The dual purpose breathing apparatus combines all the capabilities of a self-
contained breathing apparatus and a supplied-air respirator in one unit. The
apparatus is approved by the NIOSH and MSHA for use in oxygen deficient
atmospheres or where dangerous concentrations of toxic gases or vapors are
present. The NIOSH/MSHA approval allows:
• The wearer of the apparatus to enter or exit a dangerous area using only
the cylinder air in applications such as emergency rescue
• The wearer to work within the area for a limited time using the cylinder air
• The wearer to work within the area for an extended time using air from a
supply line.
Thus, the dual purpose breathing apparatus has all the advantages of both air and
work masks. Note particularly that 20% of the cylinder air may be used for entry
and that the apparatus is not limited to escape. Of course, if the air from the
supply line should fail, the wearer can escape the area using the cylinder air.
The dual purpose breathing apparatus is available in both demand and pressure
demand models. In the demand model, air is supplied on demand at ambient
atmospheric pressure. In the pressure demand model, a slight positive pressure is
maintained within the facepiece during both inhalation and exhalation. The slight
positive pressure prevents a toxic atmosphere from leaking into the facepiece; this
type of leakage can occur with a demand apparatus due to the negative pressure
developed in the facepiece. A pressure demand apparatus should therefore be
used where the potential toxicity of the atmosphere is such that no back leakage
can be tolerated.
The regulator on the dual purpose breathing apparatus reduces the high pressure
from the apparatus's compressed air cylinder to a breathable pressure. In pressure
demand models, it also automatically monitors the flow of air into the facepiece
so as to maintain a slight positive pressure within the facepiece. The regulator has
two inlet ports - one for the cylinder and another for the supply line. A connector
allows the air supply to be semi-automatically switched from the cylinder to the
air line. With no supply line connected to the regulator, the wearer receives air
from the cylinder. When an air line is connected to the regulator through the
fitting, the wearer automatically receives air from the supply line. If the air
supply from this line should be interrupted, the wearer must disengage the supply
line in order to automatically receive air from the cylinder.
Limitations of the Pressure Demand and Demand SCBA. The air supply is
limited to the amount in the cylinder and therefore the respirator cannot be used
for extended periods without recharging or replacing cylinders.
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Because these respirators are bulky and heavy, they are often unsuitable for
strenuous work or use in confined spaces.
The demand type SCBA works in a negative pressure mode and is considered
obsolete.
Special Considerations of the Pressure Demand SCBA. As specified in ANSI
Z88.2, only the pressure-demand type SCBA should be selected for emergency
use, rescue, and re-entry into a contaminated area to perform emergency
shutdown or maintenance of equipment.
Section 72
The performance of SCBAs in high temperature environments, such as fires may
lead to rapid deterioration of components.
PROTECTION FACTORS
The overall protection afforded by a given respirator design is defined in terms of
its protection factor (PF). The PF is defined as the ratio of the concentration of
contaminant in the atmosphere to the concentration inside the facepiece or hood
under conditions of use.
Protection Factors may not be appropriate where chemical or other respiratory
hazards exist in addition to radioactive hazards or where the mode of entry is
through the skin and not through inhalation. For example, 50% of the intake from
exposure to tritiated oxide is through skin absorption. The use of atmosphere
supplying respirators will only provide a PF of 2.
Application of PF's is relatively straight forward. The work area airborne
radioactivity concentration is divided by the PF to estimate the inhaled
concentration. For example, a worker performing steam generator eddy current
testing with a full facepiece continuous air flow air line respirator (PF = 1000) and
in an atmosphere of 1 x 10-6 uCi/cc Co-60 would be estimated to inhale a
concentration of 1 x 10-9 uCi/cc Co-60.
2.07.05 Define the term protection factor (PF).
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Table 1 - Assigned Protection Factors (29 CFR 1910.134)5
Type of respirator1, 2 Quarter
mask
Half mask Full
facepiece
Helmet/
hood
Loose-
fitting
facepiece
1. Air-Purifying Respirator 5 310 50 .............. ..............
2. Powered Air-Purifying Respirator
(PAPR)
.............. 50 1,000 425/1,000 25
3. Supplied-Air Respirator (SAR) or
Airline Respirator
• Demand mode
• Continuous flow mode
• Pressure-demand or other
positive-pressure mode
..............
..............
..............
10
50
50
50
1,000
1,000
..............
425/1,000
..............
..............
25
..............
4. Self-Contained Breathing
Apparatus (SCBA)
• Demand mode
• Pressure-demand or other
positive-pressure mode (e.g.,
open/closed circuit)
..............
..............
10
..............
50
10,000
50
10,000
..............
..............
Notes:
1. Employers may select respirators assigned for use in higher workplace concentrations
of a hazardous substance for use at lower concentrations of that substance, or when
required respirator use is independent of concentration.
2. The assigned protection factors in Table 1 are only effective when the employer
implements a continuing, effective respirator program as required by this section (29
CFR 1910.134), including training, fit testing, maintenance, and use requirements.
3. This APF category includes filtering facepieces, and half masks with elastomeric
facepieces.
4. The employer must have evidence provided by the respirator manufacturer that testing
of these respirators demonstrates performance at a level of protection of 1,000 or greater
to receive an APF of 1,000. This level of performance can best be demonstrated by
performing a WPF or SWPF study or equivalent testing. Absent such testing, all other
PAPRs and SARs with helmets/hoods are to be treated as loose-fitting facepiece
respirators, and receive an APF of 25.
5. These APFs do not apply to respirators used solely for escape. For escape respirators
used in association with specific substances covered by 29 CFR 1910 subpart Z,
employers must refer to the appropriate substance-specific standards in that subpart.
Escape respirators for other IDLH atmospheres are specified by 29 CFR 1910.134
(d)(2)(ii).
Section 73
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RESPIRATOR FIT TESTING
Definitions:
Qualitative fit test: Test to determine if there is any mask leakage,
usually using irritant smoke ("Go/no-go" test but no
measured value is assigned).
Quantitative fit test: Test to determine quantity of mask leakage and
assign a "fit factor," corn oil is the typical
challenge atmosphere used (Measures
concentration in mask due to leakage against
concentration in atmosphere) or a particle counting
instrument, such as a Portacount, which counts
ambient particles in the air..
It is impractical to perform a quantitative fit test prior to each entry requiring respiratory
protection. Therefore, qualitative tests are performed to ensure an adequate fit for the
user. Qualitative tests can use challenge atmospheres such as Isoamyl Acetate (banana
oil) or irritant smoke (e. g., stannic chloride) or as a negative or positive pressure test.
The irritant smoke test is the most effective since the wearer's obvious discomfort from
the smoke will show leakage through the respirator face seal. However, the test produces
noxious odors for not only the wearer but those in the test area. The use of "banana oil"
requires a subjective evaluation by the wearer and more often than not a user will not
admit that in-leakage has occurred. One reactor respiratory program was faithfully
utilizing the banana oil to perform the fit test and virtually all wearers indicated no in-
leakage through the facepiece. Unfortunately, the respirator only contained a particulate
filter cartridge rather than an organic vapor cartridge. Since most reactors use respirators
at many different locations, challenge atmosphere tests are difficult to perform and
therefore the "immediately prior-to-use" qualitative test normally selected is to perform a
negative pressure test.
Additional factors to be considered in fit testing acceptance criteria are the use of
communication devices or sorbent canisters with respirators. The respirator
2.07.07 State the recommended physical functions the subject must perform during a
respirator fit test.
2.07.06 State the difference between a qualitative and quantitative fit test.
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approval is voided if any communication device is attached to the facepiece,
unless the device is listed in the NIOSH/MSHA approval sheet.
In addition to fit testing personnel, the respirator face pieces and cartridges must
be periodically tested. Common practices are to test a portion of particulate
cartridges upon procurement and to test all particulate cartridges prior to re-use.
Anytime the filter is used by a different individual or on a different day by the
same individual, the filter is considered as being reused and should be tested for
efficiency, resistance and radioactive contaminants. As long as the inhalation
valve for the respirator is in place and functions normally, concern for biological
contaminants is of the filter is minimal.
The subject performs at least the following functions during fit testing:
1) Normal breathing
2) Deep breathing
3) Moving head from side to side
4) Moving head up and down
5) Frown
6) Talking
7) Running in place
8) Normal breathing
SELECTION
Section 74
Equipment selected must be certified by NIOSH or specifically authorized by
DOE. Approvals for respiratory devices are authorized in accordance with 42
CFR 84 and the device, type and certification number are listed in NIOSH
publication entitled, Certified Equipment List.
Selection of the proper respirator for any given situation shall require consideration of the
following:
• The nature of the hazard
• The characteristics of the hazardous operation or process
2.07.08 State how the term protection factor (PF) is applied to selection of respiratory
protection equipment
2.07.09 State the general considerations and considerations for the nature of the hazard
when selecting the proper respiratory protection equipment.
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• The location of the hazardous area with respect to a safe area having
respirable air
• The period of time for which respiratory protection may be provided
• The activity of the workers in the hazardous area
• The physical characteristics, functional capabilities, and limitations of
respirators of various types
• The respirator-protection factors and respirator fit
The following factors concerning the nature of the hazard requiring the use of
respirators shall be considered in respirator selection:
• The type of hazard
- Oxygen deficiency
- Contaminant
• The physical and chemical properties
• The physiological effects on the body
• The peak and average concentrations of toxic material or airborne
radioactivity level
• The established permissible time-weighted average or peak concentration
of toxic material, or both, or established maximum permissible airborne
radioactivity level (or administrative control levels for radiation dose) for
radioactive substances
• Whether the hazard is an immediately-dangerous-to-life-or-health
concentration of toxic material
• Warning properties
Recognition and evaluation of the respiratory hazard (oxygen deficiency or
contaminant(s)) shall be an essential part of selecting a respirator except in
emergency or rescue operations. Initial monitoring of the respiratory hazard shall
be carried out to obtain data needed for the selection of proper respiratory
protection. The data should include:
• Identification of the type of respiratory hazard
- Oxygen deficiency
- Specific contaminants
• Nature of contaminants
- Particulate matter
- Vapors or Gases
• Concentration of respiratory hazard
The following factors concerning the hazardous operation or process shall be
taken into account in selecting the proper respirator:
• Operation, process, and work-area characteristics
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• Materials, including raw materials, end products, and byproducts (actual
and potential)
• Worker activities (Modification in the operation or process shall be taken
into account, since this may change the hazard and hence require the
selection of a different respirator.)
Selection of air-line respirators includes not only the PF but also the air supply
pressure, the air flow to the user and hose length. Each manufacturer's approval
sheet lists the approved criteria. For use of 15 to 50 ft of hose at 16 to 20 pounds
per square inch, an airflow of greater than 4 CFM to a facepiece, 6 CFM to a
hood, and less than 15 CFM to either must be obtained. As discussed, air flow
rate delivery should be evaluated for multiple personnel use of breathing air
manifolds.
Section 75
SITE RESPIRATORY EQUIPMENT
(Insert site specific material here)
AIR QUALITY TESTING
An air quality testing program for all sources of respirable air is required.
Compressed breathing air shall meet at least the quality specification for Grade D
breathing air as described in Compressed Gas Association Commodity
Specification G-7.1-1989.
Section 5 of G-7.1 provides acceptable analytical procedures for measuring the
respirable air components. Oxygen is easily measured using standard oxygen
detectors which utilize an electrolytic reaction to generate a current proportional
to the oxygen content. However, a number of reactors perform the measurement
incorrectly as the oxygen percentage is determined by the partial pressures of the
oxygen in the monitored atmosphere versus the calibrated atmosphere. The test is
often performed by placing the detector probe directly in line with the pressurized
supply line. Since the air is measured at an increased pressure, the partial
pressure will appear greater relative to the calibration partial pressure and an
overestimate of the oxygen concentration will result. A better method is to
sample the oxygen in a plastic bag and then insert the probe and withdraw the air
2.07.10 Identify the types of respiratory equipment available for use at your site.
2.07.11 Identify the quality specifications breathing air must meet.
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at a reduced pressure condition. Carbon dioxide and carbon monoxide are easily
evaluated using either in line continuous monitors or grab sample "indicator
tubes". The method at your facility will be determined by the designated
Respirator Program Administrator.
The test for condensed hydrocarbons is usually performed by filtering the air,
weighing the filter and calculating the concentration by assuming the additional
filter weight is due to condensed hydrocarbons. For service air systems, the air
quality tests should also include monitoring for radioactive contaminants. The
test for radioactive contaminants is necessary as a number of service air and
breathing air systems have been cross contaminated from radioactive waste or
auxiliary boiler contaminants.
The frequency of performing air quality tests is not specified by regulation or in
standards. For bottled air systems, such as SCBAs or respirator air supply
cylinders, the tests should be performed on a representative sample of the bottles
upon receipt at the facility. For facilities which compress respirable air and fill
their own SCBAs, the sampling should be performed prior to each lot fill, once
during the lot fill and once upon completion of the lot fill. For compressed air
supply systems such as fixed station breathing air systems the sampling frequency
is best performed prior to each use of a specific manifold system. However, this
may be impractical during a major refueling outage where supplied respirable air
is extensively used at different stations. In cases of heavy usage, then a daily
check of the system may be more appropriate.
SORBENTS AND PROTECTION AGAINST RADIOIODINES
Section 76
The regulations specifically prohibit the use of PFs for canister sorbents as
protection against radioiodine atmospheres. The efficiency of the charcoal
canister is dependent upon the chemical form of the radioiodine, humidity of the
atmosphere, and breathing rate of the user. Approval can be obtained from DOE
to use PFs for sorbent cartridges. A criteria for testing and certifying the charcoal
cartridges is contained in NUREG/CR-3403, "Criteria and Test Methods for
Certifying Air-Purifying Respirator Cartridges and Canisters Against
Radioiodine." A brief summary of test conditions and acceptance criteria are as
follows in Table 2:
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Table 2 - Test Conditions and Acceptance Criteria
Test Parameter Criteria
Vapor
Concentration
Temperature
Total Airflow
Equilibration
(6H at 64 L/min)
Maximum Penetration
Minimum Service Life
CH3I
1 ppm
30 + 1 C
64 L/min
All as received
3 at 50% RH
3 at 75% RH
01 PPM
30 min at 100% RH (extrapolated) 60 min at
75% RH
Limiting conditions of use:
Total challenge in the work place (radioactive iodine, non-radioactive iodine or
the halogenated compounds) may not exceed 1 ppm.
Temperature in the work area may not exceed 100 ΕF. Temperature to be
measured on each shift or in conjunction with operations which produce heat in
the work area.
Respirator wearers must have demonstrated a fit factor greater than 100 on the
full facepiece respirator type to which the GMR-1 is attached.
Service life is 8 hours maximum. This is calculated from the time the canister is
unsealed and includes periods of non-use. Once the screw cap on the canister
threads or the tape seal over the inlet port on the bottom are removed, the 8 hour
use duration begins whether used or not by an individual.
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Canisters will not be used in the presence of organic solvents, vapors, or
chemicals (such as decontamination compounds, lubricants, volatilized paint,
alcohol, freon) which could cause aging, poisoning or desorption of the adsorbed
radioiodines. Non-exposure to these organic agents must be demonstrated by
usage restrictions and by air sampling.
Canisters must be stored in sealed humidity-barrier packaging in a cool, dry
environment (QA Class "A" storage).
COMMUNICATIONS
Although conventional respirators distort the human voice to some extent,
adequate communication can be maintained in relatively quiet areas. For power
reactors, those areas requiring the greatest use of respiratory protection are often
the noisiest due to the numerous pumps, motors and fans. Consequently, special
attachments or modifications to the respiratory device are often needed to ensure
adequate communication.
Section 77
A mechanical speech-transmission device, called a speaking diaphragm, is an
integral part of the facepiece in some respirators. It usually consists of a resonant
cavity and diaphragm which transmit sound. The diaphragm also acts as a barrier
to the ambient atmosphere and thus should be handled carefully to prevent
possible puncture which would permit leakage of an air contaminant into the
respirator. Various methods of electronically transmitting and amplifying speech
through the respirator are available. These utilize a microphone connected to a
speaker, telephone, or radio transmitter. Usually, the microphone is mounted
inside the respiratory-inlet covering, while the amplifier, power pack, and speaker
or transmitter are attached to the exterior of the respiratory-inlet covering, carried
on the body, or remotely located. Respirators with electronic speech-transmission
devices having a battery power supply should be used with caution in explosive
atmospheres. Sealed power sources shall be checked for integrity of the seals.
Connecting cables from the microphones inside the respiratory inlet covering
shall have gas-tight seals where they pass through the covering. When the
speaker diaphragm is part of the barrier between the respirator wearer and the
ambient atmosphere, it shall be and should be adequately protected from
puncture or rupture. A microphone mounted on the respirator wearer's throat or
head or a microphone/speaker worn in the respirator wearer's ear does not require
penetration of a respirator facepiece by a cable.
Any communication device that is an integral part of the respirator or is attached
to the exterior such as a sound transducer on the face plate, must be part of the
NIOSH approval for the respiratory device.
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SUMMARY
All respiratory protection devices share a common limitation for protection
against hazardous substances which injure the skin or eyes (except SCBAs) or are
absorbed through the skin. When selecting any protective device, the chemical
form of the hazardous substance should be ascertained to determine if skin
protection is required and if the eye protection afforded by the respirator is
adequate.
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DOE-HDBK-1122-2009
Module 2.08 Radioactive Source Control Study Guide
2.08-1
Course Title: Radiological Control Technician
Module Title: Radioactive Source Control
Module Number: 2.08
Objectives:
2.08.01 Describe the requirements for radioactive sources per 10 CFR 835.
→⇒ 2.08.02 Identify the characteristics of radioactive sources that must be
controlled at your site.
→⇒ 2.08.03 Identify the packaging, marking, and labeling requirements for
radioactive sources.
→⇒ 2.08.04 Describe the approval and posting requirements for radioactive
materials areas.
→⇒ 2.08.05 Describe the process and procedures used at your site for storage and
accountability of radioactive sources.
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INTRODUCTION
Section 78
A radioactive source is material used for its emitted radiation. Sources are
constructed as sealed or unsealed and are classified as accountable or exempt.
Radioactive sources are used for response checks in the field, functional checks,
calibration of instruments and monitors to traceable standards. To ensure the
safety and welfare of all personnel it is important to maintain control of
radioactive sources. Radioactive sources are controlled to minimize the potential
for:
• Spread of contamination
• Unnecessary exposure to personnel
• Loss or theft
• Improper disposal
References:
1. 10 CFR 835 (2007), “Occupational Radiation Protection”.
In accordance with 10 CFR 835, Subpart M, the following provisions apply to
sealed sources:
1. §835.1201 Sealed Radioactive Source Control
Sealed radioactive sources shall be used, handled, and stored in a manner
commensurate with the hazards associated with operations involving the
sources.
2. §835.1202 Accountable Sealed Radioactive Sources
(a) Each accountable sealed radioactive source shall be inventoried at
intervals not to exceed six months. This inventory shall:
(1) Establish the physical location of each accountable sealed
radioactive source;
(2) Verify the presence and adequacy of associated postings and
labels; and
2.08.01 Describe the requirements for radioactive sources as outlined in 10 CFR 835.
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(3) Establish the adequacy of storage locations, containers, and
devices.
(b) Except for sealed sources consisting solely of gaseous radioactive
material or tritium, each accountable sealed radioactive source shall be
subject to a source leak test upon receipt, when damage is suspected,
and at intervals not to exceed six months. Source leak tests shall be
capable of detecting radioactive material leakage equal to or exceeding
0.005 μCi.
(c) An accountable sealed radioactive source is not subject to periodic
source leak testing if that source has been removed from service. Such
sources shall be stored in a controlled location, subject to periodic
inventory, and subject to source leak testing prior to being returned to
service.
(d) An accountable sealed radioactive source is not subject to periodic
inventory and source leak testing if that source is located in an area
that is unsafe of human entry or otherwise inaccessible.
(e) An accountable sealed radioactive source found to be leaking
radioactive material shall be controlled in a manner that minimizes the
spread of radioactive contamination.
CONTROL OF SOURCES
Types of sources to be controlled include:
a. Accountable sealed radioactive source means a sealed radioactive
source having a half-life equal to or greater than 30 days and an
isotopic activity equal to or greater than the corresponding value
provided in Appendix E of 10 CFR 835.
b. Sealed radioactive source means a radioactive source manufactured,
obtained, or retained for the purpose of utilizing the emitted radiation.
The sealed radioactive source consists of a known or estimated
quantity of radioactive material contained within a sealed capsule,
sealed between layer(s) of non-radioactive material, or firmly fixed to
a non-radioactive surface by electroplating or other means intended to
prevent leakage or escape of the radioactive material.
c. Source leak test means a test to determine if a sealed radioactive
Section 79
source is leaking radioactive material.
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Responsibilities for controlling these sources include the following:
a. It is important that the following actions be done:
1) establishing the program
2) maintaining records related to the accountability and control of
accountable sealed radioactive sources for a facility
3) providing each source custodian with an inventory list of
accountable sealed radioactive sources assigned to him or her
4) assisting the source custodian in training source users
b. The source custodian:
1) should be responsible for ensuring that tests to establish the
integrity of an accountable sealed radioactive source are conducted
and inventory checks are performed at least every 6 months.
2) should maintain records of the storage and use locations of all
assigned accountable sealed radioactive sources.
3) should be trained as a radiological worker prior to being designated
as a source custodian.
4) should notify and obtain approval of the RCO prior to:
a) any major changes in the use of a sealed radioactive source
b) on-site transfer of a sealed radioactive source to a new
permanent storage location
c) modification of a device containing a sealed radioactive
source
d) disposal or off-site transfer of a sealed radioactive source
e) any procurement or acquisition of additional sealed
radioactive sources
5) should also notify the RCO in the event of the loss or damage to
any accountable sealed radioactive source
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c. The source user:
1) should be an individual trained by the RCO and the source
custodian to use either accountable or exempt sealed radioactive
sources
2) should be trained as a radiological worker and receive appropriate
training on handling their specific sealed radioactive source(s).
Sources are controlled using the following precautions:
• Each source is to be inspected before each use.
• Remove damaged sources from service.
• Fingers, whether gloved or not, or other objects should never be allowed
to touch the active surface of unsealed sources.
• Protect the source from being contaminated when used in a surface
contamination area.
(Insert site specific information here)
RECEIPT
Prior to receipt of accountable sealed radioactive sources, the RCO should assign
the sources to the proper source custodians. Immediately upon receipt of
accountable sealed radioactive sources, the RCO should be notified. The
packaging should be inspected for damage and a contamination and radiation
survey performed. The RCO should perform receipt surveys (RCS 431.3). Upon
receipt from radioactive material
transportation, external surfaces of packages known to contain radioactive
material shall be monitored if the package: (1) Is labeled with a Radioactive
White I, Yellow II, or Yellow III label (as specified at 49 CFR 172.403 and
172.436-440); or (2) Has been transported as low specific activity material (as
defined at 10 CFR 71.4) on an exclusive use vehicle (as defined at 10 CFR 71.4);
or (3) Has evidence of degradation, such as packages that are crushed, wet, or
damaged (10 CFR 835.405(b)).
2.08.02 Identify the radioactive sources that must be controlled at your site.
DOE-HDBK-1122-2009
Section 80
Module 2.08 Radioactive Source Control Study Guide
2.08-6
Monitoring per § 835.405(b) is not required for packages transported on a DOE
site which have remained under the continuous observation and control of an
individual who is knowledgeable of and implements required exposure control
measures. This obviates the need to monitor packages being transported from
building to building where the person conducting the transport has knowledge that
the package has not experienced significant challenges to its integrity (e.g., been
dropped, crushed, soaked, etc.)
The source custodian should be notified of the arrival of the sealed sources to
ensure that proper accountability and control are initiated. The sources should be
placed into storage or into the device in which they will be used. The source
custodian and site's records should be updated to include the new sources
received.
LABELING AND STORAGE OF RADIOACTIVE SOURCES
(Insert site specific information here)
Labeling requirements from 10 CFR 835 include:
(a) Items and containers may be excepted from the radioactive material
labeling requirements of 10 CFR 835.605 when:
(1) Used, handled, or stored in areas posted and controlled in accordance
with this subpart and sufficient information is provided to permit
individuals to take precautions to avoid or control exposures; or
(2) The quantity of radioactive material is less than one tenth of the values
specified in Appendix E of 10 CFR 835 and less than 0.1 Ci; or
(3) Packaged, labeled, and marked in accordance with the regulations of
the Department of Transportation or DOE Orders governing
radioactive material transportation; or
(4) Inaccessible, or accessible only to individuals authorized to handle or
use them, or to work in the vicinity; or
(5) Installed in manufacturing, process, or other equipment, such as
reactor components, piping, and tanks; or
2.08.03 Identify the packaging, marking, and labeling requirements for radioactive
sources.
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(6) The radioactive material consists solely of nuclear weapons or their
components.
(b) Radioactive material labels applied to sealed radioactive sources may be
excepted from the color specifications of §835.601(a)
Sealed radioactive sources not in storage containers or devices and not labeled by
the manufacturer must be clearly marked with a radiation symbol and have a
durable label/ tag containing the following information:
• Radionuclide
• Amount of activity
• Name of manufacturer
• Date of assay
• Model and serial numbers (where available)
RADIOACTIVE MATERIALS AREAS
(Insert site specific information here)
Definitions from 10 CFR 835 for posting of radioactive materials areas include:
(a) Radioactive Material Area means any area within a controlled area,
accessible to individuals, in which items or containers of radioactive
material exist and the total activity of radioactive material exceeds the
applicable values provided in Appendix E to 10 CFR 835.
(b) Radioactive Material Area Posting The words “Caution, Radioactive
Material(s)” shall be posted at each radioactive material area.
(§835.603(g))
§835.604 Exceptions to posting requirements
(a) Areas may be excepted from the posting requirements of §835.603 for
Section 81
periods of less than 8 continuous hours when placed under continuous
observation and control of an individual knowledgeable of, and
empowered to implement, required access and exposure control measures.
2.08.04 Describe the approval and posting requirements for radioactive materials
areas.
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2.08-8
(b) Areas may be excepted from the radioactive material area posting
requirements of §835.603(g) when:
(1) Posted in accordance with §§835.603(a) through (f); or
(2) Each item or container of radioactive material is labeled in accordance
with this subpart such that individuals entering the area are made
aware of the hazard; or
(3) The radioactive material of concern consists solely of structures or
installed components which have been activated (i.e., such as by being
exposed to neutron radiation or particles produced by an accelerator).
(c) Areas containing only packages received from radioactive material
transportation labeled and in non-degraded condition need not be posted in
accordance with §835.603 until the packages are monitored in accordance
with §835.405.
In addition, storage rooms or cabinets containing radioactive sources should meet
the following:
• Locked and posted
• Located to minimize damage from fire
• Free of flammable substances
• Isolated from occupied areas or located in radiological areas or
radiological buffer areas
• When selected in continuously occupied controlled areas, the radiation
level at the closest approach is as low as reasonably achievable and does
not exceed 0.5 millirem per hour on average
Gamma radioactive sources (except small counting radioactive sources that are
low energy and low activity or well shielded) should be stored separate from
locations where radiation detection/counting equipment is present.
SOURCE DISPOSAL
Obsolete, excess, or leaking accountable sealed radioactive sources should be
disposed of according to RCO instructions.
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SUMMARY
Sources may be sealed or unsealed, accountable or exempt. Controls for sources
are governed by DOE requirements. Responsibility for source control is
delineated in contractor procedures. The RCT needs to be knowledgeable of
controls used to prevent contamination and minimize exposure. All on-site
sources require prior written approval. Accountable sources are identified,
inventoried, surveyed and tested (sealed only). The use and disposition of sources
is maintained on records.
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DOE-HDBK-1122-2009
Module 2.09 Environmental Monitoring Study Guide
2.09-1
Course Title: Radiological Control Technician
Module Title: Environmental Monitoring
Module Number: 2.09
Objectives:
2.09.01 State the goals of an environmental monitoring program.
2.09.02 State the exposure limits to the general public as they apply to
environmental monitoring.
2.09.03 Define the term "critical nuclide."
2.09.04 Define the term "critical pathway."
→ 2.09.05 State locations frequently surveyed for radiological contamination
Section 82
at outdoor waste sites associated with your site and the reasons for
each.
2.09.06 Define the term "suspect waste site," and how they can be
identified.
→ 2.09.07 Describe the methods used for environmental monitoring at your
site.
INTRODUCTION
Environmental monitoring plays a large role in the field of radiological control.
Environmental monitoring is used to estimate human population doses, determine
the impact a site has on the environment, monitor for unplanned releases as well
as quantifying planned releases, and gives us data useful in determining pathway
data. This data can then be analyzed, and such information as critical nuclides
and critical pathways can then be determined. The Radiological Control
organization is generally interested in determining activity in the ambient air, in
surface water and sediments, in ground water wells, as well as ambient dose rates
in the environment.
Another aspect of environmental monitoring that concerns all employees is the
identification of suspect waste sites. When a waste site is suspected, it is the
responsibility of the employee to report the site to the proper site authorities for
restoration and remediation efforts.
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References:
1. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
2. NCRP Report #50, "Environmental Radiation Measurements," (1976).
3. DOE Order 5400.5.
4. 40 CFR 61.
5. 40 CFR 141 (Safe Drinking Water Act).
6. 40 CFR 191.
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GOALS OF AN ENVIRONMENTAL MONITORING PROGRAM
The following are goals of an environmental monitoring program. Each is
described in the subsequent pages.
1. Estimate Human Population Doses
2. Determine Site Impact
3. Detect and Quantify an Unplanned Release
4. Meet Legal or Regulatory Requirements
5. Create and Maintain a Good Public Image
6. Obtaining Pathway Data
7. Test Adequacy of Radiological Control Measures
8. Study of Air and Water Mixing Patterns
9. "Non-Industry" Applications
Estimate Human Population Doses
ALARA dictates that we must be aware of changes in radiation exposure to the
general population which results from nuclear operations. Issuing TLD's to the
population is not practical. In addition the TLD's are not sensitive enough to
detect changes in environmental radiation levels. The only practical way to
determine population exposure is by measurement of environmental radiation
levels:
• External radiation level
• Radioactivity present in air
• Radioactivity present in food
• Radioactivity present in water
Population exposure can then be determined by using these values combined with
a knowledge of the drinking water sources and the types of food consumed in the
region.
2.09.01 State the goals of an environmental monitoring program.
2.09.02 State the exposure limits to the general public as they apply to environmental
monitoring.
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Determine Site Impact (DOE Order 5484.1 and DOE/EH-0173T)
Environmental levels are determined prior to beginning site operations. A pre-
Section 83
operational survey (or characterization) is required for a minimum of 1 year, and
preferably 2 years, prior to the startup of any new site or waste site.
Environmental levels are then measured during site operation. Changes are
tracked to determine site impact. The exposure of members of the public to
radiation sources as a consequence of all routine DOE activities, outside of
controlled areas, shall not cause, in a year, an effective dose equivalent greater
than 100 mrem (1 mSv). The 100 mrem effective dose equivalent in a year is the
sum of the effective dose equivalent from exposures to radiation sources external
to the body during the year plus the committed effective dose from radionuclides
taken into the body during the year. The DOE primary standard of 100 mrem to
members of the public in a year is lower than the previous primary limit of 500
mrem. The lower value was selected in recognition of the ICRP recommendation
to limit the long-term average effective dose equivalent to 100 mrem per year, or
less. Experience suggests that the lower dose is readily achievable for normal
operations of DOE facilities. A higher dose limit, not to exceed the 500 mrem
effective dose equivalent recommended by the ICRP as an occasional annual
limit, may be authorized for a limited period if it is justified by unusual operating
conditions.
Note: Refer to Module 2.04 for discussion of equivalencies in the dosimetric
terms between ICRP 26/30 and 60/68 and limits for members of the public inside
controlled areas.
For airborne emissions from all DOE sources of radionuclides, the exposure of
members of the public to radioactive materials released to the atmosphere as a
consequence of routine DOE activities shall not cause members of the public to
receive, in a year, an effective dose equivalent greater than 10 mrem.
For exposure from sources from the management and storage of spent nuclear
fuel, high-level, and transuranic wastes at disposal facilities, the exposure of
members of the public to direct radiation or radioactive material released shall not
cause members of the public to receive, in a year, a dose equivalent greater than
25 mrem to the whole body or a committed dose equivalent greater than 75 mrem
to any organ.
For the drinking water pathway, it is the policy of DOE to provide a level of
protection for persons consuming water from a public drinking water supply
operated by the DOE that is equivalent to that provided to the public by the public
community drinking water standards of 40 CFR 141. These systems shall not
cause persons consuming the water to receive an effective dose equivalent greater
than 4 mrem in a year.
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Detect and Quantify an Unplanned Release
Although adequate Radiation Safety programs are maintained at all sites, there is
always the possibility of an "unknown release." Environmental monitoring can
serve as a secondary backup system to the primary defense of a good Radiation
Safety program.
• Windscale reactor fire in 1957 detected by I-131 detected downwind of
the site.
• Chernobyl detected by the Western powers through environmental
monitoring programs in Europe.
Meet Legal or Regulatory Requirements
Section 84
DOE regulations dictate environmental monitoring requirements for facilities.
Larger facilities and plants are required to maintain continuous, extensive
monitoring programs according to DOE requirements, Federal and State
regulations, and regulatory guides. DOE Order 5820.2A requires monitoring of
all inactive, existing, and new low-level waste (LLW) disposal sites to assess both
radiological and nonradiological hazards. DOE Order 5820.2 requires monitoring
and maintenance of all surplus facilities prior to decontaminating or
decommissioning.
Create and Maintain a Good Public Image
Operating an environmental monitoring program more extensively than required
by law shows the licensee to be a "good neighbor." Extensive environmental
monitoring also provides added protection against lawsuits.
Obtaining Pathway Data
Department of Energy facilities, while striving to reduce releases of radioactive
material or isotopes to the environment to zero, do occasionally make planned or
unplanned releases. Among the many radionuclides that can be released from a
site, we can identify a small group of radionuclides which, if released, would
cause the largest dose contribution to the public. A critical nuclide is one of a
group of nuclides which cause the largest dose contribution to the actual
population at risk near the site. Typical "critical nuclides" for an operational
nuclear reactor include:
2.09.03 Define the term "critical nuclide."
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• Actinium-227
• Barium/Lanthanum-140
• Cesium-137
• Cobalt-60
• Hydrogen-3 (Tritium)
• Iodine-131
• Plutonium-238
• Plutonium-239
• Manganese-54
• Radium-226
• Strontium-89
• Strontium-90
• Thorium-230
• Thorium-232
In order for any of these radionuclides to contribute dose to the public, there must
be a way for the nuclides to move from the site to the public. A "pathway" is any
route that radioactivity can follow in passing from a site to a person in the general
population where it becomes internally deposited or contributes external dose. A
critical pathway, then, is the route taken, from the point of release to body entry,
of a critical radionuclide which causes human exposure.
Environmental monitoring enables pathway data to be collected and analyzed.
This can help verify or reject theoretical "transport mechanism" data used in
determining population exposure.
Test Adequacy of Radiological Control Measures
Small amounts of non-routine radionuclides beginning to show up in the
environmental samples could indicate problems at the site. Radiological Controls
and operations at the site can then be reviewed and tightened prior to any releases
above the prescribed limits.
Study of Air and Water Mixing Patterns
To aid in the study of transport mechanisms, small amounts of radioisotopes are
sometimes released under controlled conditions to determine air and water
pathways. This data is used in determining population dose estimates.
"Non-Industry" Applications
2.09.04 Define the term "critical pathway."
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• Atmospheric and oceanic circulation studies.
• Monitoring of redistribution of radioactivity due to man's use of
Section 85
radioactive materials, and man's extensive modification of the earth's
surface. Redistribution of naturally-occurring radionuclides in the
environment can cause significant changes in the background radiation
levels in an area. Changes are made by bringing in topsoil from other
areas, the use of fertilizers, plowing the ground, the addition of water to
the ground, the presence of structures, and a whole host of other changes
that people make. Many of these changes may significantly alter the
radionuclide content in the area. The addition of water to the ground or
the presence of buildings can serve to attenuate radiation, but may also
introduce new radionuclides to the area. Industrial activities can also
result in the emission of naturally occurring radionuclides to the air or
water, which results in a redistribution of radioactivity.
PRINCIPLES OF PROGRAM DESIGN
In order to meet regulatory requirements, environmental monitoring programs
must be operated at DOE facilities. One of the main reasons to operate an
environmental monitoring program is to determine what increases in radioactivity
in the environment is due to the operation of the site. Prior to operating a site, an
environmental monitoring program will be run in order to document ambient
radiation levels that exist in the environment prior to the new site's start up. We
can also locate any naturally occurring radiation anomalies in the environment.
We document meteorology patterns, and use this information to help identify
critical nuclides and critical pathways for the new site.
Another phase of environmental monitoring is entered once the site begins
operations. Measurements are now made to aid in dose assessment, for the
determination of compliance with allowed releases, and for the identification of
any changes in radioactivity in the environment due to the operation of the site.
In order to accomplish these goals, we need:
• A monitoring program with enough sensitivity to detect environmental
changes in radioactivity.
• A monitoring program with enough selectivity to be able to separate
nuclides of interest from background interference.
The post-operational program is commonly on a smaller scale than the pre-
operational program. Due to the extensive monitoring done prior to start of
operations, attention of the post-operational can be focused primarily on the
critical nuclides, and the instrumentation on the critical pathways.
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2.09-8
RADIOLOGICAL CONTROL RESPONSIBILITIES
Radiological Surveys are Conducted to Monitor Radioactive Contamination
General Monitoring Requirements:
• Ambient air in the immediate vicinity of active and inactive sites.
• Surface water (rivers, estuaries, lakes and oceans) and sediments are
monitored for constituents indicating the status of operational practices
and control.
• Soil and vegetation are monitored to detect possible contamination from
fallout and uptake.
• Ground water wells are surveyed to ensure their physical integrity.
• Background dose rates are monitored near facilities that may have
elevated dose rates.
• Radiation surveys are performed to detect contamination spread.
Survey frequencies for particular sites are to be determined by the
technical judgement of Environmental Protection and/or Radiological
Control and may depend on the site history, radiological status, use and
general conditions.
Section 86
Appropriate documentation must be completed for each environmental survey.
Radiological Surveys are performed on:
(Insert site specific information here.)
SUSPECT WASTE SITES
2.09.05 State locations frequently surveyed for radiological contamination at outdoor
waste sites associated with your site and the reasons for each.
2.09.06 Define the term "suspect waste site," and how they can be identified.
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A suspect waste site is any site that is thought for any reason to contain
dangerous waste, hazardous waste and/or radioactive waste. This does not
include sites already identified.
Suspect Waste Site Identification
Any employee having any reason to believe that a site contains dangerous waste,
hazardous waste, and/or radioactive waste should report this information to
management. The following conditions should be looked for:
• Soil discoloration is present
• An unusual soil depression or disturbance exists
• Pipes emerging from the ground (indicates a possible crib, tank or other
structure).
• Plant stress
• The unusual absence of plant life
• Vaults, chambers, concrete or steel structures, drums, pipes, or munitions
protruding from the surface of a disturbed area
• Holes, sinkholes, or collapsed structures (indicates the presence of man-
made structures or voids beneath the surface)
• The presence of hazardous and/or radioactive material in soil samples
• Documentation or personnel interviews which indicate the past existence
of a waste disposal site.
ANALYSIS OF ENVIRONMENTAL SAMPLES
Environmental sample types include:
• Air samples
• Soil samples
• Vegetation samples
• Animal samples
• Surface water samples
• Groundwater samples
• Background radiation
• Radiation surveys
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Methods of Monitoring
Environmental levels of external gamma radiation are measured using film or
thermoluminescent dosimeters. The lower detection level for film badges is
approximately 10 mrem/month. The lower detection level for TLD's is
approximately 1 mrem a month. Corrections must be made, however, for fading
of 1 mrem/month dependence.
Activity deposited on the ground (or "fallout") is isotopically analyzed and
quantified to determine release point of origin and amount released. Generally,
gas-flow proportional counters are used for gross alpha and beta determinations.
Gamma spectrum are obtained using Germanium semiconductor systems. Alpha
spectroscopy can also be used to isotopically analyze and quantify environmental
samples.
Fallout simply means radioactive particles that settle out onto the ground. The
term does not necessarily imply a nuclear detonation has occurred.
"Flypaper" technique is used, which consists of an adhesive covered piece of
waterproof paper, which is positioned in the environment to catch and hold
particulate matter which settles out. This technique traps approximately 70% of
the particles that fall on it.
Rain water is also collected and analyzed for radioactivity that may have been
washed from the air.
Grass and other broadleaf vegetation is also a good collection media for "fallout."
(Note how this may be part of a critical pathway, e.g., cows graze on
contaminated pastures, and the general population drinks the now contaminated
milk).
Section 87
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OTHER TYPES OF ENVIRONMENTAL SAMPLES
Atmospheric sampling is accomplished in several ways depending on the physical
properties of the airborne radioactivity, such as the chemical properties of the
activity and the phase of the activity (particulate or gas or vapor):
• Air sampling for particulates
Inertial separation is one method for radioactive particulate air sampling.
It is especially effective in determining the size distribution of particles.
This information is necessary for internal dose assessment following
inhalation of particulate radionuclides. A Cascade Impactor is an example
of a sampler utilizing the inertial separation method
Filtration is another method for radioactive particulate air sampling. This
consists simply of a pump which pulls air through a filter matrix. The
filter is then removed and counted to determine airborne radioactive
particulate concentrations. Dust loading is a factor in collection
efficiency. As the filter becomes plugged up with dust, air flow generally
decreases, but the collection efficiency usually increases The rate at
which air (particles) is drawn through the filter also is a factor in
collection efficiency. At low rates of air flow, efficiency is relatively high
due to diffusion of particles in the filter media. In other words, the air
particles "drift" through the filter media, and become trapped in the dead
air spaces in the filter. At high rates of air flow, efficiency is also
relatively high due to the phenomena of impaction. This is an increased
collection of particles due to the higher speed of the particles causing them
to "crash" into the filter media, and bury themselves in the fibers of the
filter. It is necessary to realize, however, that for gross beta and especially
gross alpha counting, this method will introduce more self-shielding in the
counting process. Radon and Thoron may mask actual activity of the
filter, however, some counting methods can avoid this problem.
• Air sampling for gases
Continuous flow sampling for radioactive gases is a common method of
air concentration determination. Air is pumped or exhausted through a
chamber housing a detector. The detector, coupled with an air flow-rate
meter, can give real-time determination of airborne radioactivity
concentration. An example of a system utilizing this method is a Stack
Monitor.
Grab sampling is another method of measuring air activity concentration.
This method uses an evacuated chamber which is opened in the
environment to be sampled, then re-sealed. The inside surfaces of the
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2.09-12
chamber are coated with a scintillation phosphor, such that when different
types of radiation interact with the phosphor, small flashes of light are
produced. When the chamber is placed in a light-tight housing with a
photomultiplier tube, these flashes of light are measured and are indicative
of the activity concentration in the grab cell. Another type of grab sampler
is an evacuated tube or chamber with a thin-walled G-M tube mounted
along it's central axis. For analysis, then, the G-M is connected to a scaler,
and a gross count is made.
Section 88
Adsorption is the assimilation of gas, vapor or dissolved matter by the
surface of a solid or liquid (the adsorbent). Gaseous air activity
concentration is measured by drawing the air to be measured through the
adsorbent, and then counting the adsorbent. Common adsorbents are
activated charcoal, silver zeolite (AgZ), and silica gel.
Condensation is used in monitoring for airborne tritium activity. Water
vapor in the air which may contain tritium components are condensed by
using a super-cooled strip of metal in the ambient air. Water vapor will
condense and freeze on this strip. The ice is then melted, and a liquid
scintillation counter is then used to count for tritium.
Aquatic samples may include sediments, bottom organisms, vegetation, fin fish or
shell fish. Water needs to be analyzed only if it is used for consumption or
irrigation. In most cases, samples of shell fish and fin fish are saved to document
the principal route of human exposure. If waste is being discharged into a
flowing stream of potable water, a continuous sampler should be used.
Food Sampling is not necessary if proper regulations are followed that restrict the
discharge of liquid and solid radioactive effluents (other than that which is
desirable for good relationships with the public). The type of sampling will be
determined by the isotope released. Radionuclides such as Co-60 and Zn-65
concentrate in shellfish. Consumption of oysters from Willipa Bay, Washington,
proved to be a pathway for Zinc-65 from the Hanford reactors even though the
oyster beds were 30 miles from the mouth of the Columbia River and the reactors
over 200 miles upriver from the mouth of the Columbia River.
Sampling should be done if these radioactive fission products are discharged into
an estuary populated with shellfish. If I-131 is released, cow pastures should be
sampled as well as the milk produced. I-131 will appear in the milk within 24
hours, The need for analysis of food increases near nuclear facilities. Regional
and national monitoring programs continue to be required due to fallout from
weapons testing.
2.09.07 Describe the methods used for environmental monitoring at your facility.
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SITE ENVIRONMENTAL MONITORING PROGRAMS
(Insert site specific information here.)
TRANSPORT MECHANISMS
Atmospheric Transport
Airborne radioactive contaminants are carried downwind and dispersed by normal
atmospheric mixing processes. Internal irradiation occurs if the radionuclides are
inhaled and incorporated in the body. External irradiation occurs by beta and
gamma irradiation from the plume. Material is removed from the plume by
impaction of the plume with the ground surface or by washout due to rain.
Deposition of the material from the plume leads to further exposure pathways
through:
• Direct external exposure from contaminated surfaces
• Inhalation of re-suspended material
• Ingestion of contaminated foodstuffs.
Factors considered in determining the deposition of radioactive material back to
earth include:
• Wind speed
• Temperature
• Stack height
• Particle size
• Weather conditions.
A reverse in the normal upward movement of hot air can slow down the dilution
of radioactive release. The condition where hot air develops over cooler air is
called a temperature inversion. A temperature inversion can occur when:
Section 89
• A warm front covers a cooler earth
• A cool front is injected under warm air (sea breeze)
• The normal cycle of a summer day when the earth cools off faster than the
air above.
Surface Water Transport
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Liquid effluents may be discharged into various types of surface water bodies:
rivers, estuaries, lakes and oceans. In rivers, the rate of transport is slower than in
the atmosphere. Radionuclides may be absorbed by bottom sediments, and may
accumulate in the aquatic biota. Although these two processes involve only a
small fraction of the inventory, they may be significant with respect to radiation
exposure.
Radioactive materials released in rivers eventually feed into the ocean. In the
ocean surface layer (75m in depth and located above the thermocline) the mixing
time is 3-5 years. Below the thermocline in the deep ocean, the mixing is much
slower.
Some aquatic mixing factors include:
• Depth of water
• Type of bottom
• Shoreline configuration
• Tidal factors
• Wind
• Temperature
• Salinity
• Solubility of radioactive material
• Depth at which pollutant is introduced.
Movement in the Ground
Radionuclide movement in the ground is generally the slowest. Movement of
most radionuclides depends upon convective transport in water. In humid regions
the rate of ground water movement near the surface is on the order of 1 ft/day. In
arid areas, the rate is much slower. There is an abundance of solid material for
absorption of radionuclides and interaction with this geologic media can reduce
the rate of radionuclide movement to a small fraction of underground water
movement.
RADIOISOTOPES OF CONCERN
Plutonium (Pu-239)
Pu-239 is tightly bound by soils and is present in plants in only minute amounts.
Very small amounts of Pu-239 are transferred to plants through root uptake.
Plutonium has a tendency to stick to any material in which it comes in contact.
The critical organ for Pu in the insoluble oxide compound is the lung. If Pu is in
soluble form and ingested, the critical organ is the bone.
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Properties of Pu-239:
Radiological half-life (Tr): 24,400 years
Biological half-life (Tb): 203 years
Effective half-life (Te): 200 years
Sources: Produced in thermal reactors by neutron irradiation of U-
238. In nuclear weapons and as fuel for fast reactors.
Radiation, Energy (MeV): α (alpha), 5.15, 5.14, 5.10
Chemistry: Member of the Actinide series of rare-earth elements.
Forms insoluble fluorides, hydroxide, and oxides; soluble
complexes with citrate and nitrate.
Effective Half Life of Pu is shown in the following formula:
Te = Tr x Tb
Tr + Tb
Strontium (Sr-89, Sr-90)
Rainfall increases the fallout of strontium from the atmosphere. It appears to
build up the greatest in the soils with a high exchangeable calcium content. The
strontium content of plants is due in part to uptake from soil and in part from
foliar deposition. The dietary sources of strontium depend partly on the food
consumption habits of the population and the manner in which the food is
processed or prepared. The bone is the critical organ for Sr-89 and Sr-90.
Properties of Sr-90:
Section 90
Radiological half-life: 28.1 years
Biological half-life: 50 years
Effective half-life: 17.8 years
Source: Fission product
Radiation, Energy (MeV): β-, .546 Mev
Chemistry: Alkaline earth element similar to calcium
Iodine (I-131)
Because of the short half-life of I-131 (8 days), it is not a significant
environmental contaminant insofar as its uptake from the soil is concerned. The
decay rate is relatively rapid in relation to the growing time of a crop, and any
significant contamination by means of root uptake would, for this reason, be
improbable. Radioiodine deposited on the surfaces of plants can be ingested
directly by cattle and passed in this way to milk or other dairy products. Since the
time between collection and consumption is relatively short, the possibility of
iodine contamination of fresh milk must be considered. Contamination of
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Module 2.09 Environmental Monitoring Study Guide
2.09-16
powdered milk is less of a problem because a longer storage time will permit
decay of the isotope. Fresh fruit and vegetable stands may also be a potentially
important source to local populations. I-131 is soluble and readily absorbed
through skin, lungs, and GI tract. The critical organ is the thyroid.
Properties of I-131:
Radiological half-life: 8.05 days
Biological half-life: 138 days
Effective half-life: 7.6 days
Sources: Fission product
Radiation, Energy (Mev): β-, .606 ; γ, 0.364
Chemistry: I-131 is a halogen element. The milk content of I-131 reaches
its peak 3 days after deposition. The effective half-life of removal from
grass is 5 days.
Cesium (Cs-137)
Cesium-137 is bound so tightly by the clay minerals of the soil that the root
uptake is slight, and foliar absorption is, therefore, the main method of entry to
the food chains. The uptake of Cs-137 from the soil has been shown to be
inversely proportional to the potassium deficiency. Although cow's milk is the
largest single contributor of Cs-137 to the U. S. adult diet, other foods including
grain products, meat, fruit, and vegetables contribute 2/3 of the dietary Cesium
intake. The critical organ is the whole body.
Properties of Cs-137:
Radiological half-life: 30 years
Biological half-life: 45-150 days
Effective half-life: 45-150 days
Source: Fission product
Radiation, Energy (Mev): β-, 0.514 ; γ, 0.662
Chemistry: Alkali metal with properties similar to potassium (K) and
Rubidium (Rb); most salts are soluble.
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2.10-1
Course Title: Radiological Control Technician
Module Title: Access Control and Work Area Setup
Module Number: 2.10
Objectives:
→ 2.10.01 State the purpose of and information found on a Radiological Work
Permit (RWP) including the different classifications at your site.
→ 2.10.02 State responsibilities in using or initiating a RWP.
→ 2.10.03 State the document that governs the ALARA program at your site.
→ 2.10.04 Describe how exposure/performance goals are established at your site.
→ 2.10.05 State the conditions under which a pre-job ALARA review is required
at your site.
→ 2.10.06 State the conditions under which a post-job ALARA review is required
at your site.
2.10.07 State purpose of radiological postings, signs, labels, and barricades;
and the RCTs responsibilities for them.
Section 91
→ 2.10.08 Identify the following radiological postings at your site, requirements
for posting/barriers, and requirements for entry:
a. Radiological Buffer Area
b. Radiation Area
c. High Radiation Area
d. Very High Radiation Area
e. Hot Spot
f. Contamination Area
g. High Contamination Area
h. Airborne Radioactivity Area
i. Fixed Surface Contamination
j. Soil Contamination
k. Radioactive Material Area
l. Underground Radioactive Material Area
2.10.09 Describe good practices, support equipment to use, and common
discrepancies in setting up radiological areas.
2.10.10 List discrepancies frequently observed in containment devices.
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2.10.11 Describe good practices in setting up portable ventilation systems and
count rate meters.
→ 2.10.12 List the requirements individuals should follow while working in
RBAs.
→ 2.10.13 State the requirements for removing or releasing materials from any
radiological area.
INTRODUCTION
This lesson reviews Radiological Work Permits, various types of postings used in
radiological areas, setting up radiological areas, access controls, and releasing of
material from radiological areas.
References:
1. 10 CFR 835 (2007), “Occupational Radiation Protection”.
2. DOE Radiological Control Standard (2008).
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RADIOLOGICAL WORK PERMITS (RWP)
(Insert site specific information here)
The RWP is an administrative mechanism used to establish radiological controls
for intended work activities. The RWP informs workers of area radiological
conditions and entry requirements and provides a mechanism to relate worker
exposure to specific work activities. The RWP should include the following
information:
• Description of work
• Work area/process radiological controls
• Dosimetry requirements
• Pre-job briefing requirements, as applicable
• Training requirements for entry
• Protective clothing and respiratory protection requirements
• Radiological control coverage requirements and stay time controls, as
applicable
• Limiting radiological conditions that may void the RWP
• Special dose or contamination reduction considerations
• Special personnel frisking considerations
• Technical work document number, as applicable
• Unique identifying number
• Date of issue and expiration
• Authorizing signature
2.10.01 State the purpose of and information found on a Radiological Work Permit
(RWP) including the different classifications at your site.
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Radiological Work Permits are required for activities such as entry into High or
Very High Radiation Areas, entry into High Contamination Areas, or any entry
into Airborne Activity Areas.
Other activities that might require the use of a RWP include entry into Radiation
Areas, entry into Contamination Areas, or handling of materials with removable
contamination that exceeds the values in Table 2-2 of the Radiological Control
Standard..
(Insert site specific information here)
Workers accessing an area permitted by an RWP are required to sign the RWP or
log prior to initial entry and after any revisions to the RWP. This process
signifies that the worker has read the RWP. The workers signature signifies that
he/she is aware of the radiological conditions and agrees to comply with the
requirements.
Section 92
There are basically two types of RWPs, Job-specific and General. General RWPs
govern routine or repetitive work where radiological conditions are stable such as
general inspections, surveillances, surveys, and tours. General RWPs may be
used to govern specific maintenance and operations when such jobs do not
involve work with elevated or complex radiological conditions. General RWPs
are typically valid for one year. Job-specific RWPs are used to control nonroutine
operations or work in areas with higher level or changing radiological conditions.
Job-specific RWPs usually remain in effect only for the duration of the job.
ALARA CONSIDERATIONS FOR ACCESS CONTROL AND WORK AREA
SETUP
Exposure to ionizing radiation is typically quantified, tracked, and controlled in
terms of the equivalent dose workers receive, or could potentially receive, in
given situations. Management policy is to maintain radiation exposure of
employees, subcontractors, visitors and members of the general public not only
within applicable DOE and administrative limits, but "As Low as Reasonably
Achievable."
2.10.02 State responsibilities in using or initiating a RWP.
2.10.03 State the document that governs the ALARA program at your site.
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Documentation
(Insert site specific information here)
Exposure/Performance Goals
(Insert site specific information here)
PRE-JOB ALARA REVIEWS
Pre-job ALARA reviews are required to be held prior to the conduct of work
anticipated to exceed trigger levels. An example of this would include a work
area with removable beta/gamma contamination levels greater than 100,000
dpm/100cm2.
Pre-job meetings are held with employees who will be involved in work activities
involving unusual radiological conditions. These meetings allow an open
discussion of all the factors identified as effective dose reduction measures. RC
needs are communicated to workers. Worker needs are communicated to RC.
Procedures are verified, worker qualifications are verified, and what they do in an
emergency is discussed. At the end of the meeting, everyone should know what is
expected of them, how to do it, and the conditions under which it is to be done.
Pre-job briefings are usually conducted by the cognizant work supervisor and as a
minimum, the pre-job briefings should include:
• Scope of work to be performed
• Radiological conditions of the workplace
• Procedural and RWP requirements
• Special radiological control requirements
2.10.04 Describe how exposure/performance goals are established at your site..
2.10.05 State the conditions under which a pre-job ALARA review is required at your
site.
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• Radiologically limiting conditions, such as contamination or radiation
levels that may void the RWP
• Health Physics/Radiological Control Hold Points
• Communications and coordination with other groups
• Provisions for housekeeping and final cleanup
• Consideration of potential accident situations or unusual occurrences and a
review of abnormal and emergency procedures and plans
• Emergency response provisions.
Site requirements for pre-job reviews:
(Insert site specific information here)
POST-JOB ALARA REVIEWS
Section 93
Post-job ALARA reviews allow the opportunity to critique the work performance.
Although they will not affect the dose already received for a particular job, they
can be effective in reducing the doses received the next time that job is
performed.
As a minimum, the post-job ALARA review should include the following, as
applicable:
• Any changes/modifications made to original work instructions.
• Time required to perform the job.
• Resources required for job.
• Estimated collective dose versus actual collective dose summary.
• Effectiveness of exposure controls implemented.
• Problems encountered and solutions.
2.10.06 State the conditions under which a post-job ALARA review is required at your
site.
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• Abnormal events/situations causing the use of stop work.
• Lessons learned.
• Actions taken to prevent recurrence of problems or situation.
An example of when a post-job ALARA review is required is when a job has had
actual doses 30% higher than expected.
Site requirements for post-job reviews:
(Insert site specific information here)
RADIOLOGICAL POSTINGS
The purpose of radiological postings, signs and labels is to identify items or areas
that have the potential for, or actually contain, radiological hazards; identify the
radiological hazard(s) present in an area and to prevent workers from
inadvertently entering radiological area(s), and/or mishandling radioactive
materials.
Each individual is responsible to read and comply with all the information
identified on radiological postings, signs and labels. Since there may be more
than one radiological hazard identified on a posting, sign or label, it is important
to read all of the information and not just the first line.
All access points into an area must be posted to ensure workers are adequately
warned of the hazards in the area. Postings and status boards (if applicable)
should be promptly updated after completion of a survey to reflect the corrected
conditions in the area.
If necessary, the RWP should be amended to reflect any changes in the area. The
information on status boards, RWPs, posting and survey maps should be
consistent. If there is a discrepancy it should be immediately corrected. Workers
could review erroneous data that has not been updated and subsequently become
contaminated or receive some unnecessary radiation exposure.
2.10.07 State purpose of all radiological postings, signs, labels, and barricades; and the
RCTs responsibilities for them.
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Radiological Control Technicians should immediately update postings after
performing a survey. The RWP and any status boards must also be updated. If
the posting was updated and the RWP was not, a worker may consider the RWP
correct and the posting wrong. If a worker entered the area based on the incorrect
RWP information he/she could become contaminated or receive unnecessary
radiation exposure.
Areas should be posted if there is a strong potential for the situation to exist, even
if it is not now present. Areas can be posted as Airborne Radioactivity Areas or
Surface Contamination Areas, if equipment in the area has been known to leak
and create airborne or contamination hazards. Posting areas in such a situation
will ensure that the proper protective equipment is used and could prevent
personnel contamination or unplanned internal exposure.
Section 94
If areas are posted only when the appropriate limits have been reached, personnel
can be subjected to hazards when the hazard could have otherwise been
minimized.
Disregarding any radiological posting, sign or label can lead to unnecessary or
excessive radiation exposure and/or personnel contamination.
Unauthorized removal or relocation of radiological postings, signs and labels may
lead to disciplinary actions up to and including job termination. If any type of
material used to identify radiological hazards is found outside a RBA, it should be
reported to radiological control personnel immediately. The RCT would then
perform a survey of the sign, posting or label and conduct a survey of the area in
which it was found.
Any contamination or higher than expected radiation levels must be promptly
reported to the RCT supervisor.
2.10.08 Identify the following radiological postings at your site, requirements for
posting/barriers, and requirements for entry:
a. Radiological Buffer Area
b. Radiation Area
c. High Radiation Area
d. Very High Radiation Area
e. Hot Spot
f. Contamination Area
g. High Contamination Area
h. Airborne Radioactivity Area
i. Fixed Surface Contamination
j. Soil Contamination
k. Radioactive Material Storage Area
l. Underground Radioactive Material Area
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TYPE OF RADIOLOGICAL POSTINGS, SIGNS AND LABELS
Radiation Area: Any area, accessible to individuals, in which radiation levels
could result in an individual receiving an equivalent dose to the whole body in
excess of 0.005 rem (0.5 millisievert) in one hour at 30 cm from the source or
from any surface that the radiation penetrates.
High Radiation Area: Any area, accessible to individuals, in which radiation
levels could result in an individual receiving an equivalent dose the whole body in
excess of 0.1 rem (0.001 sievert) in one hour at 30 cm from the source or from
any surface that the radiation penetrates.
Very High Radiation Area: Any area, accessible to individuals, in which radiation
levels could result in an individual receiving an absorbed dose in excess of 500
rads (5 grays) in one hour at 1 m from the source or from any surface that the
radiation penetrates.
Airborne Radioactivity Area: Any area, accessible to individuals, where (1) the
concentration of airborne radioactivity, above natural background, exceeds or is
likely to exceed the derived air concentration (DAC) values listed in Appendix A
or Appendix C of 10 CFR 835; or (2) an individual present in the area without
respiratory protection could receive an intake exceeding 12 DAC-hours in a week.
10 CFR 835 requires the following:
1. §835.601 General Requirements
(a) Areas shall be posted in accordance with this subpart to provide
warning to individuals of the presence, or potential presence, of
radiation and/or radioactive materials.
(b) Except as provided in §835.602(b), postings and labels required by
this subpart shall include the standard radiation warning trefoil in
black or magenta imposed upon a yellow background.
(c) Signs required by this subpart shall be clearly and conspicuously
posted and may include radiological protection instructions.
(d) The posting and labeling requirements in this subpart may be
modified to reflect the special considerations of DOE activities
conducted at private residences or businesses. Such modifications
shall provide the same level of protection to individuals as the
existing provisions in this subpart.
Section 95
2. §835.602 Controlled areas
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(a) Each access point to a controlled area (as defined in §835.2) shall
be posted whenever radiological areas exist in the area.
Individuals who enter only the controlled area without entering
radiological areas are not
expected to receive a total effective dose of more than 100 mrem
(0.001 sievert) in a year.
(b) Signs used for this purpose may be selected by the contractor to
avoid conflict with local security requirements.
3. §835.603 Radiological areas
Each access point to a radiological area (as defined in §835.2) shall be
posted with conspicuous signs bearing the wording provided in this
section.
(a) Radiation Area. The words “Caution, Radiation Area” shall be
posted at each radiation area.
(b) High Radiation Area. The words, “Caution, High Radiation Area”
or “Danger, High Radiation Area” shall be posted at each high
radiation area.
(c) Very High Radiation Area. The words “Grave Danger, Very High
Radiation Area” shall be posted at each very high radiation area.
(d) Airborne Radioactivity Area. The words “Caution, Airborne
Radioactivity Area” or “Danger, Airborne Radioactivity Area”
shall be posted at each airborne radioactivity area.
(e) Contamination Area. The words “Caution, Contamination Area”
shall be posted at each contamination area.
(f) High Contamination Area. The words “Caution, High
Contamination Area” or “Danger, High Contamination Area” shall
be posted at each high contamination area.
(g) Radioactive Material Area. The words “Caution, Radioactive
Material(s)” shall be posted at each radioactive material area.
4. §835.604 Exceptions to posting requirements
(a) Areas may be excepted from the posting requirements of §835.603
for periods of less than 8 continuous hours when placed under
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continuous observation and control of an individual knowledgeable
of, and empowered to implement, required access and exposure
control measures.
(b) The following areas may be excepted from the radioactive material
area posting requirements of §835.603(g):
(1) Areas posted in accordance with 835.603(a) through (f);
and
(2) Areas in which each item or container of radioactive
material is clearly and adequately labeled in accordance
with §§835.605 and 835.606 such that individuals entering
the area are made aware of the hazard.
(c) Areas containing only packages received from radioactive material
transportation need not be posted in accordance with §835.603
until the packages are surveyed in accordance with §835.405.
Area designations
(Insert site specific information here)
Entry Requirements
(Insert site specific information here)
SETTING UP RADIOLOGICAL AREAS
Good practices to be considered whenever possible in setting up Radiological
Areas: establish walkways in low dose areas; do not store radioactive materials
near walkways or where personnel frequently work; place rope boundaries as
close to the source of contamination as possible to minimize the size of the
contaminated area. Care must be taken to ensure the area is not so limited that
contamination is easily spread across the boundaries.
Section 96
Use drip trays or containment devices to prevent the spread of contamination.
Establish laydown areas for equipment to limit personnel safety hazards and/or
radiation exposure. Set up SOPs upwind of contamination hazards. Post all
accessible sides and entrance(s) to areas containing radiological hazards.
2.10.09 Describe good practices, support equipment to use, and common
discrepancies in setting up radiological areas.
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Use Personnel Contamination Monitors (PCMs) along with portable
contamination survey instrumentation whenever possible. PCMs are more likely
to detect contamination on individuals because personnel tend to survey too
quickly. If this happened with an actual contamination incident the employee
could subsequently pass over the contamination areas with the portable
contamination survey instrumentation.
The following are commonly observed discrepancies that should be avoided in the
setup of Radiological Areas:
• Posting information not updated or information otherwise incorrect.
• Boundaries not verified for contamination, radiation, and airborne
radioactivity hazards.
• Survey instruments out of calibration or defective.
• Step-off-pads not set up for efficient removal of protective clothing (not
enough room to prevent contaminating the SOPs) and not near survey
instrumentation.
• Laundry and waste receptacles not placed for efficient use or not placed at
all. Receptacles not properly labeled as to their contents.
• Boundaries of areas setup too far from the hazards interfering with access
to areas otherwise unaffected.
• Count rate meters not located close to the step-off-pads.
• Status boards or survey maps do not reflect where SOPs and boundaries
lie.
• Status board not kept up-to-date. The information on status boards,
postings and RWPs should agree. Postings should be updated at least
every 24 hours while an RWP is in use and reflect current radiation and
contamination levels in the area.
• Tripping hazards exist from wires, hoses, or cables.
• Background radiation in monitoring area too high for efficient detection of
low level contamination.
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• Portable contamination survey instrumentation not set up for proper
operation.
• Protective clothing (gloves and booties) not readily available in a
personnel contamination event.
• Phone or other communication devices not available near the SOP or
portable contamination survey instrumentation.
• Not posting all accesses points into area.
• Failure to post dress and undress procedures.
Since contamination or airborne radioactivity and radiation levels are subject to
change, it is essential to be able to quickly establish a Radiological Area. To
properly set up a Radiological Area, the following support equipment should be
readily available:
• Step-off-pads.
• Portable contamination survey instrumentation/personnel contamination
monitors to establish at exits to Contamination Areas, Airborne
Radioactivity Areas, and RBAs.
• Yellow and magenta rope, ribbon or tape.
• Laundry receptacles.
• Waste receptacles (clean and radioactive waste receptacles).
• Receptacles for defective protection clothing (optional).
• Receptacles for non-compactable waste (optional).
Section 97
• Receptacles for mixed waste (optional).
• Electrical power supply and extension cords (optional).
• Postings, signs, labels, and posting inserts.
• Communication equipment readily available.
• Additional protective clothing.
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• Dose rate meters and smears.
• Survey maps.
CONTAINMENT DEVICES
Containment devices include glove boxes, glove ports, hot cells, huts, and
windbreaks. Common discrepancies observed in containment devices include:
• Holes/leaks in the containments or is maintained at a positive pressure,
facilitating the spread of contamination.
• Liquids accumulating in hoses or main portions of the containment.
• Airlocks too small to remove protective clothing without spreading
contamination.
• Ventilation exhaust not directed to the plant ventilation system.
• Material allowed to accumulate inside containments, limiting safe and/or
efficient use.
• Sharp objects used inside containments.
• Devices not tethered to prevent introduction into systems.
• Transfer sleeves/ports are not used or are unavailable.
• Containment not provided with a HEPA filter or ventilation exhaust.
• Containments not periodically surveyed inside and out.
• No means of quickly verifying loss of ventilation.
• Containment not decontaminated prior to dismantling.
• Adequate access not provided for lines or hoses.
2.10.10 List discrepancies frequently observed in containment devices.
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• Containment not maintained at a negative pressure.
• Containment not supported properly to minimize stress from minor
ventilation changes or not structurally supported to maintain its
configuration during use.
• Containments not inspected prior to use and periodically during use.
• Not using appropriate containment devices for leaks.
• Not using a funnel to collect leakage.
• Plastic components showing fatigue or wear.
• Funnel not positioned to collect all leaking fluid.
• Drain lines kinked allowing the buildup of liquids.
• Drain lines not secured properly to the collection device.
• Containment device not labeled to indicate hazards that are present.
PORTABLE VENTILATION SYSTEMS
Portable ventilation systems are frequently used to remove contaminated air or
filter contamination in the air. Radiological control personnel should adhere to
the following good practices in setting up portable ventilation systems.
Good practices to be used for the set-up of portable ventilation systems include:
• Use only HEPA (High Efficiency Particulate Air) filters with pre-filters
(roughing filters)
• Perform radiation survey on filters periodically while in use.
• Have radiological limits established for filter replacement.
• Exhaust filter discharge to the plant ventilation system whenever possible.
2.10.11 Describe good practices in setting up portable ventilation systems and count
rate meters.
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• Ensure that there are no openings in the trunk or between the blower and
the filter.
• Monitor the filter differential pressure (d/p) periodically.
• Establish filter d/p at which the filter must be replaced.
Section 98
• Remove filters into plastic bags to prevent the release of activity.
• Position streamers to signify the flow of ventilation through doorways or
through containment devices.
CONTAMINATION MONITORING EQUIPMENT
The proper setup and use of portable contamination survey instrumentation and
personnel contamination monitors (PCMs) can ensure that contamination is more
likely to be detected on workers. The following is a list of good practices for
setting up portable contamination survey instrumentation and PCMs:
• They must be placed in low background area.
• They need reliable power supply.
• They should be positioned to facilitate easy access by workers.
• Alarms should be set to site administrative control levels or DOE limits.
• Must ensure instrument is source checked and calibrated.
• Extension cords must be checked for electrical safety.
• Portable contamination survey instrumentation and PCMs should be
placed upwind of contaminated areas.
• They should not be placed near radioactive material storage areas or other
areas where the background radiation can change.
• Portable contamination survey instrumentation should have sources
provided to source check the instrument.
ACCESS CONTROL
10 CFR 835 requires the following:
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§835.501 Radiological Areas
(a) Personnel entry control shall be maintained for each radiological
area.
(b) The degree of control shall be commensurate with existing and
potential radiological hazards within the area.
(c) One or more of the following methods shall be used to ensure
control:
(1) Signs and barricades;
(2) Control devices on entrances;
(3) Conspicuous visual and/or audible alarms;
(4) Locked entrance ways; or
(5) Administrative controls.
(d) Written authorizations shall be required to control entry into and
perform work within radiological areas. These authorizations shall
specify radiation protection measures commensurate with the
existing and potential hazards.
(e) No control(s) shall be installed at any radiological area exit that
would prevent rapid evacuation of personnel under emergency
conditions.
§ 835.502 High and very high radiation areas.
(a) The following measures shall be implemented for each entry into a
high radiation area:
(1) The area shall be monitored as necessary during access to
determine the exposure rates to which the individuals are
exposed; and
(2) Each individual shall be monitored by a supplemental
dosimetry device or other means capable of providing an
immediate estimate of the individual's equivalent dose to
the whole body during the entry.
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(b) Physical controls. One or more of the following controls shall be
used for each entrance or access point to a high radiation area
where radiation levels exist such that an individual could exceed an
equivalent dose to the whole body of 1 rem (0.01 sievert) in any
one hour at 30 centimeters from the source or from any surface that
the radiation penetrates:
(1) A control device that prevents entry to the area when high
radiation levels exist or that, upon entry, causes the
radiation level to be reduced below the level that defines a
high radiation area;
(2) A device that functions automatically to prevent use or
Section 99
operation of the radiation source or field while individuals
are in the area;
(3) A control device that energizes a conspicuous visible or
audible alarm signal so that the individual entering the high
radiation area and the supervisor of the activity are made
aware of the entry;
(4) Entryways that are locked. During periods when access to
the area is required, positive control over each entry is
maintained;
(5) Continuous direct or electronic surveillance that is capable
of preventing unauthorized entry;
(6) A control device that will automatically generate audible
and visual alarm signals to alert personnel in the area
before use or operation of the radiation source and in
sufficient time to permit evacuation of the area or
activation of a secondary control device that will prevent
use or operation of the source.
(c) Very high radiation areas. In addition to the above requirements,
additional measures shall be implemented to ensure individuals are
not able to gain unauthorized or inadvertent access to very high
radiation areas.
(d) No control(s) shall be established in a high or very high radiation
area that would prevent rapid evacuation of personnel.
Entry and Exit Requirements for Radiological Buffer Areas
2.10.12 List the requirements individuals must follow while working in RBAs.
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(Insert site specific information here)
Besides meeting the requirements for entry into Radiological Areas and RBAs,
personnel must also ensure that they take appropriate measures to maintain their
exposures ALARA.
• Workers who receive radiation exposures from other nuclear facilities
must report the exposure to site radiological control personnel and their
supervisor upon returning to the site.
• Avoid contact with potentially contaminated surfaces.
• Any management/supervision or site radiological control personnel should
give stop work or evacuation orders if unanticipated radiation or
contamination is encountered or if the appropriate RWP is not being
followed.
• Wear dosimeter(s) in accordance with the RWP.
• Maintain exposure ALARA.
• Report all injuries.
• Monitor clothing and exposed skin as required and report the presence of
radioactive contamination.
• Place contaminated items and waste in approved radioactive waste
containers.
• Personnel should wash their hands when leaving the RBA and prior to
eating or using tobacco products.
• Personnel who are not respiratory qualified should not enter areas posted
as "Respiratory Protection Required"
Hot Particles
Hot particles are small, discrete, highly radioactive particles capable of causing
extremely high doses to a localized area in a short period of time. Hot particle
contamination may be present or be generated when contaminated systems are
opened or when operations such as machining, cutting or grinding are performed
on highly radioactive materials.
DOE-HDBK-1122-2009
Module 2.10 Access Control and Work Area Setup Study Guide
2.10-20
• The Site-Specific Radiological Control Manuals usually define hot
particles. Typically they will be described as very small discrete particles
capable of producing an equivalent dose to the skin greater than 100 mrem
in one hour.
• Special surveys in areas with the potential for hot particle contamination.
Section 100
• Posting areas to specifically identify the presence of hot particles.
• Controlling access to hot particle areas should through a job-specific
RWP. The following controls should be considered for inclusion on the
RWP:
- Periodic personnel monitoring during the work activity, at a
frequency based on the potential magnitude of skin exposure
- Additional Personal Protective Equipment and Clothing
- Direct Radiological Control coverage during work or assistance
during protective clothing removal
- Use of sticky pads or multiple step-off pads.
• Personal Protective Equipment and Clothing used in hot particle areas
should be segregated from other radiological protective equipment and
clothing during laundering and surveyed prior to reuse.
• Response to hot particle skin contamination of personnel should include
the following:
- Immediate removal and retention of the hot particle for subsequent
analysis
- Analysis of the particle
- Assessment of worker dose
- Evaluation of work control adequacy.
REMOVING MATERIALS FROM RADIOLOGICAL AREAS
Facility operations require that radioactive material and non-radioactive material
be removed from Radiological Areas, RBAs, and from the site. Prior to allowing
this material to leave, important steps outlined in the procedures must be
followed. 10 CFR 835 requires the following:
1. §835.1101 Control of Material and Equipment
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(a) Except as provided below, material and equipment in
contamination areas, high contamination areas, and airborne
radioactivity areas shall not be released to a controlled area if:
(1) Removable contamination levels on accessible surfaces
exceed the removable surface contamination values
specified in Appendix D of 10 CFR 835; or
(2) Prior use suggests that the removable contamination levels
on inaccessible surfaces are likely to exceed the removable
surface contamination values specified in Appendix D of
10 CFR 835.
(b) Material and equipment exceeding the removable surface
contamination levels specified in Appendix D of 10 CFR 835 may
be conditionally released for movement on-site from one
radiological area for immediate placement in another radiological
area only if appropriate monitoring is performed and appropriate
controls for the movement are established and exercised.
(c) Material and equipment with fixed contamination levels that
exceed the limits specified in Appendix D of 10 CFR 835 may be
released for use in controlled areas outside of the radiological areas
only under the following conditions:
(1) Removable surface contamination levels are below the
removable surface contamination values specified in
Appendix D of 10 CFR 835; and
(2) The material or equipment is routinely monitored and
clearly marked or labeled to alert personnel of the
contaminated status.
Release to Radiological Buffer Area
(Insert site specific information here)
Release to Uncontrolled Areas
2.10.13 State the requirements for removing or releasing materials from any
radiological area.
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2.10-22
(Insert site specific information here)
SUMMARY
Section 101
This lesson addressed radiological area support and access control. The areas
covered included RWPs, radiological postings, setting up radiological areas, good
practices and discrepancies commonly observed in setup of various portions of
radiological areas, access control, and removing materials from radiological areas.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-1
Course Title: Radiological Control Technician
Module Title: Radiological Work Coverage
Module Number: 2.11
Objectives:
2.11.01 List four purposes of job coverage.
2.11.02 Explain the differences between continuous and intermittent job
coverage.
2.11.03 Given example conditions, identify those that should require job
coverage.
2.11.04 Identify items that should be considered in planning job coverage.
2.11.05 Identify examples of information that should be discussed with
workers during pre-job briefings.
2.11.06 Describe exposure control techniques that can be used to control
worker and technician radiation exposures.
→ 2.11.07 Describe the in-progress radiological surveys that should be
performed, at your site, under various radiological conditions.
→ 2.11.08 Describe site requirements for documentation of in-progress
radiological surveys.
→ 2.11.09 Explain actions that should be taken if surveys show radiological
conditions significantly different from that expected.
2.11.10 Describe contamination control techniques that can be used to limit
or prevent personnel and area contamination and/or reduce
radioactive waste generation.
2.11.11 Describe job coverage techniques that can be used to prevent or
limit the spread of airborne radioactive material.
2.11.12 Describe overall job control techniques in maintaining control of
radiological work.
2.11.13 State the reasons to stop radiological work activities in accordance
with the DOE RCS.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-2
INTRODUCTION
Jobs performed in restricted areas are usually approved and controlled by
radiological control personnel by using administrative and procedural controls,
such as Radiological Work Permits (RWPs). In addition, some jobs will require
working in, or will have the potential for creating, very high radiation,
contamination, or airborne radioactivity areas.
REFERENCES
1. DOE Radiological Control Standard (2008).
PURPOSE OF JOB COVERAGE
Job coverage by RCTs generally has four purposes:
1. To ensure worker's radiation exposures are maintained ALARA and
within limits/guidelines
2. To minimize the creation and spread of surface contamination.
3. To minimize the creation and spread of airborne radioactive material.
4. To minimize the creation of radioactive waste.
TYPES OF JOB COVERAGE
Job (or work) coverage can either be continuous or intermittent. During
continuous job coverage, the technician covers only one job and remains at the
job site while work is being performed. For intermittent coverage the technician
may cover more than one job, performing periodic checks at various work
locations.
CONDITIONS REQUIRING JOB COVERAGE
2.11.01 List four purposes of job coverage.
2.11.02 Explain the differences between continuous and intermittent job coverage.
2.11.03 Given example conditions, identify those that should require job coverage.
DOE-HDBK-1122-2009
Section 102
Module 2.11 Radiological Work Coverage Study Guide
2.11-3
Some radiological conditions or types of jobs that could require radiological
control job coverage are:
• Radiation dose rates in the job area are high enough to potentially cause
workers' doses to exceed administrative control levels in a short time.
• Radiation levels are expected to increase significantly during the job.
• Entry into high radiation areas.
• The potential for spreading high levels of contamination or causing
airborne radioactivity.
• The potential for significant increase in contamination or airborne
radioactivity levels during the job.
• Inadequate personnel dosimetry for the type or levels of expected radiation
(e.g., neutrons or low-range dosimeters).
• Jobs performed by inexperienced workers.
PREREQUISITES/WORK PLANNING
To effectively cover a job, technicians must preplan their activities. Items that
should be included in the planning include:
• Determine exactly what workers will be doing (e.g., not just "replace a
component" but the details of whether grinding, cutting or welding will be
performed).
• Review old surveys and talk with technicians who have previously
covered the same or similar jobs to anticipate any problem areas.
• Review the area and system on which the work will be performed, or talk
with the workers to determine the potential radiological consequences of
the tasks associated with the job (e.g., opening a cask / container could
create contamination, airborne radioactivity, or cause radiation levels to
change).
2.11.04 Identify items that should be considered in planning job coverage.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-4
• Ensure that an adequate survey of the job area has been made.
• Review applicable post-job ALARA reviews.
When sufficient survey documentation is not available, a pre-job survey is
usually required. This is a detailed survey performed at the job site before
the job begins that is used to determine RWP requirements. This survey
should include dose rate, contamination and representative breathing zone
air samples for the areas being accessed. The survey should identify the
highest and lowest dose rate areas. All individuals, including the tech-
nician, should stay in the low dose rate areas as much as possible.
• For jobs in which workers' dose limits could be approached, record the
allowable exposure for each worker. A good practice is to have this
information available at the job site.
• Establish communication methods with the workers prior to the job.
Workers should know how, when, where, and why to contact the RCT.
For most jobs communicating with workers is simply a matter of talking
face-to-face. However, for some jobs remote communications (e.g.,
headsets, or a safety line attached to a belt) may be required. Hand signals
may be needed when respirators are worn. Two way portable radios are
another option for communication.
• Establish a method of communicating with and transferring samples to the
radiological control counting lab.
Often an air sample taken during the job must be transferred from the job
site to the radiological control lab for analysis. Arrangements for
transferring samples, and obtaining results, should be made before the job
begins.
• Have the appropriate equipment available at the job site.
Section 103
Examples include extra dosimeters, dosimeter charger, air sampler and
filters, a survey instrument, respirator (if needed), watch or clock for time
keeping, extra gloves, and any other equipment required by the job.
Consideration of Other Hazards
When evaluation the hazards for a job evolution, it is important to consider non-
radiological hazards as well. A framework aligned with the principles and functions of
Integrated Safety Management (ISM) requires systematically integration of safety into
management and work practices at all levels so that missions are accomplished while
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-5
protecting the public, the worker, and the environment. This is accomplished through
effective integration of safety management into all facets of work planning and
execution. Under ISM, both DOE and DOE-contractor line managers are charged with
responsibility for integrating safety measures into all facets of work planning and
execution. Line managers should use their site-specific radiological control manual as a
guide to integrating radiological control measures into work planning and execution.
Both the ISM and ALARA processes require hazard controls to be tailored to the work
being performed. In addition to establishing basic radiological safety standards that must
be observed, 10 CFR 835 establishes requirements that provide significant flexibility so
that individual activities may implement compliance measures in a manner that is
commensurate with specific hazards and work activities.
On December 2, 2002, the 107th Congress amended the Atomic Energy Act by adding
Section 234.C and on December 18, 2003, DOE published a Notice of Proposed
Rulemaking in the Federal Register, entitled, “Worker Safety and Health Program.” The
Rule became final on February 9, 2006 as 10 CFR 851. This rule provides for a worker
health and safety program for DOE contractors and should be addressed in hazard
analysis evaluation for radiological operations.
• Pre-job briefing of the workers before going to the job site.
Proper pre-job briefings 10 CFR 851 Worker Safety and Health Program
On December 2, 2002, the 107th Congress amended the Atomic Energy Act by adding Section 234.C and
on December 18, 2003, DOE published a Notice of Proposed Rulemaking in the Federal Register, entitled,
“Worker Safety and Health Program.” The Rule became final on February 9, 2006.
10 CFR 851 provides for a worker health and safety program for DOE contractors and should be addressed
in hazard analysis evaluation for radiological operations.
include the technician (or line supervisor) informing workers of
radiological conditions such as: dose rates, contamination levels, and
concentration of airborne radioactivity in the work area. This should
include an explanation of the probable effect of their job on radiological
conditions. Other important points could include method of
communications that will be used, specifics about special dosimetry or
protective clothing and actions of the technician covering the job. The
RCT should cover what actions and exits to take in an emergency to
reduce worker exposure and confusion. Worker questions should be
answered prior to starting work. The technician should emphasize
radiological safety and the importance of following the RWP and it's
specific directions.
Section 104
2.11.05 Identify examples of information that should be discussed with workers during
pre-job briefings.
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2.11-6
JOB COVERAGE TECHNIQUES
The techniques in covering a job will depend upon the nature of work being done,
the radiological conditions present or expected in the work area, and to some
extent the experience of the workers. The following sections describe job
coverage techniques that may be applicable.
Exposure Control
One of the purposes of job coverage is to keep track of the dose received by
workers and suggest methods that the workers can follow to keep their doses
ALARA. At the same time, the technicians must take measures to minimize their
own dose as well. Pre-job surveys alone are not always adequate in determining
the dose rates to personnel during the job. Many jobs will require that surveys be
performed as the job progresses. The purpose and type of surveys should be
based on the level of the conditions and their probability of change. Surveys
provide information about current conditions and if the conditions are changing.
Surveys can identify unusual conditions which may lead to changing job
requirements or even stopping the job. It is just as important to record the results
of job coverage surveys as recording the results of the routine and pre-job
surveys. In addition, do not keep this information to yourself or merely log and
file the survey records. Keep the personnel in the area informed of the
radiological conditions. Technicians should explain to the workers why actions
are being taken. The following is a list of some of the techniques that can be used
to help maintain exposure control:
• Wait in low dose rate areas while not actually performing the job.
Remember that surveys of job areas should always identify low dose
areas. To reduce the amount of time spent in higher radiation levels and
consequently reduce the dose received, both technicians and workers
should stay in the lower dose rate areas whenever possible (e.g., waiting
for equipment, when resting, when visual observation of workers is
possible from a distance).
• Periodically read or have workers read their dosimeters.
2.11.06 Describe exposure control techniques that can be used to control worker and
technician radiation exposures.
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Module 2.11 Radiological Work Coverage Study Guide
2.11-7
To keep track of the dose accumulated by the workers the technician
should read or have the workers read their dosimeters. If several workers
are working on the same job, select one individual to read the others'
dosimeters. The individual that reads the dosimeters can remove one outer
glove or slip on a clean glove to lessen the chance of contaminating the
dosimeters.
• Use workers' allowable dose and the dose rate in an area to determine the
length of time a worker can spend in the area.
For jobs where workers will approach an administrative control or DOE
limit, the technician will have to determine how long a worker can remain
in an area without exceeding the authorized exposure. Detailed surveys
will determine the dose rate. The workers dose limits can be obtained
from dosimetry records. The following formula is used to determine the
amount of time the worker can stay in the area:
TIME ALLOWED = A l l o w a b l e D o s e
Section 105
Dose Rate
Remember to tell the individual to leave before the total time has elapsed.
It takes some time for the workers to respond and they may receive
significant dose going to and from the job location.
• When using time to control workers' dose, an accurate record of the
workers location with respect to the dose rate must be maintained.
On some jobs (e.g., working in a neutron radiation field) keeping track of
how long the worker is in the radiation field (Dose = Dose Rate x Time)
will be used to determine the dose received by the worker. The technician
must record the workers' locations with respect to the dose rate to
accurately calculate the dose.
• Write down the workers location and time in that location when time
keeping.
Relying on memory can be inaccurate. Record the times in the area.
• Observe the location of workers' dosimetry with respect to the location of
the radiation source.
On some jobs, the workers' heads, back, or other parts of the body could
be receiving higher dose than the chest area where dosimetry is normally
worn. Relocating the workers' dosimetry or obtaining additional
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Module 2.11 Radiological Work Coverage Study Guide
2.11-8
dosimetry may be required to obtain the highest dose received to the
whole body.
• Workers must leave temporary shielding in place unless they have been
authorized to remove the shielding by Radiological Control.
Unauthorized movement of shielding could increase the dose rate in the
work area.
• Technicians performing job coverage should move temporary shielding
only after evaluating the effect of such movement and with proper
approval.
• Perform your survey as objects are being removed from their shipping
container or cask, don't wait until the radioactive objects are withdrawn to
make the survey.
• Keep workers from leaning across or over high sources of radiation.
Possibly get them to move to the other side of equipment to do their work.
• Prevent workers from picking up sources of radiation with their hands.
They should use pliers or tongs, and carry items in a bucket or a plastic
bag rather than in the hand.
• Anytime casks, containers or equipment are being opened (or opened
further than before) recheck radiation levels, including beta radiation
levels.
In-progress radiological surveys
In-progress radiological surveys that should be performed should be performed as
specified by the controlling technical work document and Radiological Work
Permit (i.e.,., smear surveys, dose rate surveys, air samples taken).
(Insert site specific information here)
In-progress radiological survey documentation
2.11.07 Describe the in-progress radiological surveys that should be performed, at
your site, under various radiological conditions.
2.11.08 Describe site requirements for documentation of in-progress radiological
surveys.
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Module 2.11 Radiological Work Coverage Study Guide
2.11-9
Radiological Control personnel should maintain logs to document radiological
occurrences, status of work activities and information that should be
communicated to all personnel. Make field notes of survey results for later
documentation. Good practice dictates that all surveys should, at a minimum, be
documented on the appropriate map.
(Insert site specific information here)
Unexpected radiological conditions
Section 106
(Insert site specific information here)
Contamination Control
By observing the actual performance of the job, technicians can suggest methods
that could help prevent spreading contamination from one area to another and
could lessen the probability of personnel contamination. The following items
should be considered:
• Watch the workers. Point out and correct any work habits that could
spread contamination.
Even though all workers are trained in basic methods to prevent spreading
contamination during their initial Radiological Worker training course,
many workers either forget the techniques or lapse into more familiar but
contamination spreading work habits. Such habits include hand-to-face
movements, dropping tools, scuffing feet, hammering, and wire brushing.
Technicians must identify actions that will spread contamination, ask the
worker to stop the action, and explain why the actions should be stopped.
• System components that are being repaired should be wiped down and
drained before the system is opened.
2.11.09 Explain actions that should be taken if surveys show radiological conditions
significantly different from that expected.
2.11.10 Describe contamination control techniques that can be used to limit or prevent
personnel and area contamination and/or reduce radioactive waste
generation.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-10
Even though operations personnel may have drained a specific part of the
system, the workers should have plastic buckets, bags, and plastic sheeting
to contain any residual water when the system is opened.
• Ensure that workers follow procedures for transferring material from the
radiological area to either a Radiologically Controlled Area or a clean
area.
They should hold the bag over the contaminated area, only touch the
outside of the bag with clean gloves, place (not drop) items into the bag,
not overload the bag, tape sharp edges before placing in bag and not lay
the bag down in the contaminated area. Tape the bag shut and mark the
bag indicating what it contains. Large items can be covered with plastic
sheeting that is taped in place after all surfaces have been wiped off.
Wheels on carts, trolleys and cranes can be heavily taped or plastic/paper
sheeting laid down between contaminated areas to create a temporary
pathway across a clean area.
Do not allow bags of trash, tools or used parts to accumulate in the work
area or at the step off pad or control point. Obtain dose rate and
contamination surveys of all bagged or covered items being removed from
the work area before they are moved when dose rates in the area allow.
• Ensure workers follow proper procedures to minimize contaminating tools
and equipment.
By reducing the chances of contaminating tools and equipment, the
probability of spreading contamination plus the cost, radiation exposure,
and manpower involved in decontamination can be lessened. Techniques
such as taping or bagging tools
and pulling welding leads, hoses and extension cords into plastic tubing
before beginning work or using tools already contaminated should be
suggested by the technician. The reasons for the suggestions should be
explained.
• Watch for the movement of crane rigging, air or water hoses, electric leads
and extension cords into and out of contaminated areas.
Section 107
• Electrical lines and hoses going into Contaminated Areas should be
secured (taped down) to eliminate the possibility of movement in or out.
Any of the above movements could spread contamination. Be alert for
such movements and explain why they should not be made. If overhead
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Module 2.11 Radiological Work Coverage Study Guide
2.11-11
cranes are going to be used, suggest methods to lessen the spread of
contamination (e.g., papering floors along the pathway that the crane will
take).
• Have workers remove their outer layer of protective clothing (gloves, shoe
covers, and coveralls) a few feet prior to the step off pad area.
• Reduce the creation of radioactive waste.
Reduction of radioactive waste will assist in preventing the spread of
contamination and airborne radioactive material and reduce the cost and
manpower involved in processing and shipping radioactive material offsite
for burial. Before going into the Radiological Area, have the workers
remove the packaging for any new equipment they will be carrying into
the area. During performance of the job, suggest that a minimum amount
of water be used, if required. Point out to the workers other areas where
creation of radioactive waste can be reduced.
Airborne Radioactivity Control
When the creation and spread of airborne radioactivity can be controlled, the use
of respiratory protection equipment can be minimized. By watching workers and
monitoring for airborne radioactivity during a job, technicians can suggest
methods that can prevent creating airborne or warn workers when airborne radio-
activity is present. Appropriate corrective actions (e.g., respiratory protection,
evacuation of work area, stay times) can be implemented. As in exposure and
contamination control, the technicians should explain the actions required to the
workers. The following items should be considered:
• Look for any actions that could create airborne radioactivity.
Such actions could include opening systems containing radioactive
material; leaks or sprays from the system, welding, grinding, cutting on
contaminated systems; or
any actions that could disturb highly contaminated surfaces (e.g.,
hammering, wire brushing, or use of pneumatic tools). Warn the workers
and take appropriate corrective actions.
2.11.11 Describe job coverage techniques that can be used to prevent or limit the
spread of airborne radioactive material.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-12
• Take air samples during jobs in highly contaminated areas or at steps (e.g.,
opening a system to change HVAC filters) that could create airborne
radioactive material during a job.
During the performance of such jobs, workers will usually be in
respirators as a precautionary measure. Analysis of the air sample can be
used to determine the necessity of respirators and to calculate the number
of DAC-hours received by the workers.
Remember to get the sample counted and obtain the results as quickly as
possible. A grab air sample only tells you what the average airborne
radioactivity concentration was in the area while the sampler was running.
• Use a continuous air monitor (CAM) during performance of a job that is
likely to create airborne radioactivity.
Section 108
CAM results give an immediate indication of an increase in the airborne
radioactive material concentration. Appropriate protective action for
CAM alarms includes evacuation of all affected personnel and notification
of Radiological Control. Re-entry into affected areas should include the
use of respiratory protection.
• Ventilate enclosed areas.
By ventilating enclosed areas, airborne radioactive material generated in
the area can be removed. "Enclosed areas" include permanent cubicles or
rooms or temporary tents built to enclose work areas. Ventilation can be
obtained via the installed in-plant ventilation system or by using portable
fans or blowers with HEPA filters.
In certain job situations the use of respiratory protection can increase the
total equivalent dose for the job. This is referred to as "dose expansion."
Dose expansion occurs when respirator usage increases time in a
radiation/high radiation/very high radiation area to the extent more dose is
received than dose from an internal dose commitment from not wearing
respiratory protection.
2.11.12 Describe overall job control techniques in maintaining control of radiological
work.
DOE-HDBK-1122-2009
Module 2.11 Radiological Work Coverage Study Guide
2.11-13
Overall Job Control Techniques
In the preceding three sections, the specific guidelines for controlling exposure,
contamination and airborne radioactive material were discussed. In addition to
maintaining control over these three specific areas, technicians must maintain
overall control of the radiological aspects of the job.
• Establish worker trust and confidence.
Worker trust and confidence are not automatically gained by being the
RCT covering the job. Trust and confidence must be earned by each
technician and the entire plant radiological control staff. Characteristics of
technicians and health physics departments that will assist in earning
worker trust include being reliable, credible, realistic, and consistent.
• During job coverage, the technicians should keep workers within their line
of sight, if possible.
While not possible at all times (e.g., when workers and technician are
separated by a shield wall), the technician should constantly be observing
the workers. Poor work habits possibly leading to the spread of contami-
nation, creation of airborne radioactive material, and unnecessary
exposure to radiation can be identified and corrected.
• Keep in contact with the workers.
The technicians should talk with the workers to remind them that they are
covering the job and are available to answer questions or make
suggestions. This is especially important if remote communications
equipment is being used, since the workers may be apprehensive.
• Remind workers that casks, containers or systems are not to be opened or
work techniques changed without notifying radiological control.
Explain that these actions could change radiological conditions in the area
and cause unnecessary exposure to radiation or airborne radioactive
material or cause the spread of contamination.
• When an individual's work habits must be corrected, offer the correct
method as advice or help.
No worker enjoys being told that his method of doing a job is incorrect.
A belligerent, demanding approach by the technician can result in more
harm then benefit. Explain why the workers' method is incorrect and what
the possible consequences are and then offer the correct method as another
Section 109
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2.11-14
solution. Remember that as a technician your role is to assist the workers
in maintaining their exposures ALARA.
• Show a positive, helpful attitude toward co-workers.
If workers note that the technician is complacent or disinterested in the
job, the workers may become lax in following the proper procedures for
reducing their exposure and preventing the creation and spread of
contamination or airborne radioactive material. The technicians covering
the job should take an interest in the job being performed by the workers
and take pride in their own work.
• Do not overreact to situations when there is time for levelheaded solutions.
Getting excited and yelling at workers for minor problems will only result
in the workers losing any respect for the radiological control staff. Calmly
explain what the problem is and the steps that need to be taken to correct
the situations. Reserve excitement for true emergencies.
Stop Work Authority
• The DOE RCS gives Radiological Control personnel the authority and
responsibility to stop work when there are:
- Inadequate radiological controls
- Radiological controls not being implemented
- Radiological hold points not being satisfied
- Alarming dosimetry or unexpected dosimetry readings
• Exercise your authority to stop work with discretion. Remember it is your
responsibility to ensure that the work is performed safely in a radiological
environment. The following situations are examples of when work should
be temporarily halted to correct problems:
- Workers disobeying procedures or not following their RWP
- Dropped container incidents / spills
- Unexpected dose rates or surface contamination readings.
• Resumption of radiological work requires approval from the line manager
responsible for the work and the Radiological Control Manager.
2.11.13 State the reasons to stop radiological work activities in accordance with the
DOE RCS.
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2.11-15
SUMMARY
This lesson addressed radiological work coverage. The areas covered included
the conditions requiring job coverage, the prerequisites and planning involved,
and techniques associated with the coverage of radiological work.
DOE-HDBK-1122-2009
Module 2.12 Shipment/Receipt of Radioactive Material Study Guide
2.12-1
Course Title: Radiological Control Technician
Module Title: Shipment/Receipt of Radioactive Material
Module Number: 2.12
Objectives:
2.12.01 List the applicable agencies which have regulations that govern the
transport of radioactive material.
2.12.02 Define terms used in DOT regulations.
2.12.03 Describe methods that may be used to determine the radionuclide
contents of a package.
2.12.04 Describe the necessary radiation and contamination surveys to be
performed on packages and state the applicable limits.
2.12.05 Describe the necessary radiation and contamination surveys to be
performed on exclusive use vehicles and state the applicable limits.
2.12.06 Identify the proper placement of placards on a transport vehicle.
→ 2.12.07 Identify inspection criteria that should be checked prior to
releasing a shipment at your site.
→ 2.12.08 Describe site procedures for receipt and shipment of radioactive
Section 110
material shipments.
→ 2.12.09 List the actions required at your site if a shipment is received
exceeding radiation or contamination limits.
→ 2.12.10 Describe the proper step-by-step method for opening a package
containing radioactive material at your site.
REFERENCES:
1. 10 CFR 835 (2007), “Occupational Radiation Protection”.
2. 49 CFR, Parts 100-177, “Transportation”.
3. DOE Order 460.1B (2003), “Packaging and Transportation Safety”.
4. DOE Order 460.2 A (2004), “Departmental Materials Transportation and
Packaging Management.
DOE-HDBK-1122-2009
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RADIOACTIVE MATERIAL SHIPMENT REGULATIONS
The basis behind the regulations governing the packaging and shipping of
radioactive material is to keep radiation and radioactive material from affecting
the environment during transportation and to keep the environment from affecting
the integrity of the radioactive material.
The package itself is to be designed and constructed to be the effective barrier
between the environment and the radioactive material, thus most of the regulatory
restrictions apply to the package and the method of shipment used to transport the
package.
To reduce any potential hazard, the regulatory requirements become more
restrictive as the quantity, concentration, and potential hazard of the radioactive
material increases.
Regulatory Structure. Numerous governmental agencies have jurisdiction over
the transfer and shipment of radioactive material from nuclear facilities. The
primary organizations are:
• U.S. Department of Energy
• U.S. Nuclear Regulatory Commission
• U.S. Department of Transportation, Hazardous Material Bureau
• U.S. Coast Guard
• International Civil Aviation Organization or International Air Transport
Association
• State transportation departments or radiation health bureaus.
U.S. Department of Energy. The U.S. DOE establishes regulations to protect the
public health and safety from undue risk from DOE activities. These regulations
are in the form of 10 CFR 835 and DOE Orders. DOE requirements applicable to
packaging and transportation of radioactive material include:
• 10 CFR 835 – The Exclusion section of 10 CFR 835.1 states that
occupational doses received as a result of excluded activities and
radioactive material transportation shall be considered when determining
compliance with the occupational dose limits in §§835.202 and 835.207.
2.12.01 List the applicable agencies which have regulations that govern the transport
of radioactive material.
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• DOE O 460.1B – Establishes administrative procedures for the
certification and use of radioactive and other hazardous materials
packaging by DOE.
Establishes standards and requirements for the packaging and
transportation of hazardous (including radioactive) materials, substances
and wastes. This Order requires that packages for radioactive materials
meet the NRC standards in 10 CFR 71 and imposes additional restrictions.
• DOE Order 460.2A – Establishes DOE policies and procedures for the
management of materials transportation activities, including traffic
management, for other than intrabuilding and intrasite transfers. It
contains general requirements related to all transportation activities, not
just hazardous or radioactive materials.
Section 111
U.S. Department of Transportation. The U.S. DOT regulates transportation by
air, water, rail, and highway. The Materials Transportation Bureau has
established rules governing the packaging and transport of hazardous material,
including radioactive material.
These regulations are contained in 49 CFR 170 - 179 and are applicable to any
person who transports, or ships, a hazardous material. Even though most of the
requirements for shipping radioactive material are located in Part 173, the other
sections of DOT regulations must not be overlooked.
Regulatory Compliance. There are many regulations and documents from several
agencies that govern the transfer and transport of radioactive material.
Compliance with all regulations, not just those from one agency, is required to
transfer and shipment of radioactive material. The number of regulations
involved depends upon the chosen mode of transport and the quantity of
radioactive material. Each individual or group assigned the responsibility of
transferring and shipping radioactive material must maintain a complete set of
current regulations from all applicable agencies as well as other supporting
regulatory guides, licenses and clarifying documents.
Keep in mind that most regulations usually contain exemptions and may contain
more restrictive clauses. For example, the DOT may exempt some shipments of
low quantities and types of radioactive material from their regulations. The DOT
exemption, however, does not automatically exempt the material from DOE
requirements. It is best to be aware of the requirements from all agencies to avoid
citations for using one specific exemption that is not recognized by the other
agencies.
2.12.02 Define terms used in DOT regulations.
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DEFINITION OF TERMS
In order to understand the regulations, it is necessary to understand the basic
language and limits established in the regulations. The following definitions are
found in 49 CFR 173.403 (this is not a complete listing of the §173.403
definitions):
A1. The maximum activity of special form radioactive material permitted in a
Type A package.
A2. The maximum activity of radioactive material, other than special form, Low
Specific Activity, or Surface Contaminated Object, permitted in a Type A
package.
Radioactive Material. Any material having a specific activity greater than 70 Bq
per gram (0.002 microcurie per gram). No other U.S. Department or Agency uses
this limit.
Exclusive Use (also referred to as “sole use” of “full load”). Sole use by a single
consignor of a conveyance for which all intial, intermediate, and final loading and
unloading are carried out in accordance with the direction of the consignor or the
consignee. The consignor and the carrier must ensure that any loading or
unloading is performed by personnel having radiological training and resources
appropriate for safe handling of the consignment. The consignor must issue
specific instructions in writing, for maintenance of exclusive use shipment
controls, and include them with the shipping paper information provided to the
carrier by the consignor.
Limited Quantity. A quantity of radioactive material not exceeding the materials
packaging limits specified in §173.425 and conforming with requirements
specified in §173.421.
Section 112
Low Specific Activity (LSA). Radioactive material with limited specific activity
which satisfies the descriptions and limits set forth below. Shielding materials
surrounding LSA material may not be considered in determining the estimated
average specific activity of the package contents. LSA material must be in one of
three groups:
1) LSA-I
i) Ores containing only naturally occurring radionuclides (e.g.,
uranium, thorium) and uranium or thorium concentrates of ores; or
ii) Solid unirradiated natural uranium or depleted uranium or natural
thorium or their solid or liquid compounds or mixtures; or
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iii) Radioactive material, other than fissile material, for which the A2
value is unlimited; or
iv) Mill tailings, contaminated earth, concrete, rubble, other debris,
and activated material in which the radioactive material is
essentially uniformly distributed and the average specific activity
does not exceed 10-6A2/g.
2) LSA-II
i) Water with tritium concentration up to 0.8 Tbq/liter (20 Ci/liter);
or
ii) Material in which the radioactive material is distributed throughout
and the average specific activity does not exceed 10-4A2/g for
solids and gases, and 10-5A2/g for liquids.
3) LSA-III: Solids (e.g., consolidated wastes, activated materials) that
meet the requirements of §173.468 and which:
i) The radioactive material is distributed throughout a solid or a
collection of solid objects, or is essentially uniformly distributed in
a solid compact binding agent (such as concrete, bitumin, ceramic,
etc.); and
ii) The radioactive material is relatively insoluble, or it is intrinsically
contained in an insoluble material, so that even under loss of
packaging, the loss of radioactive material per package by leaching
when placed in water for seven days would not exceed 0.1 A2; and
iii) The average specific activity of the solid does not exceed
2x10-3A2/g.
Normal Form. Radioactive material which has not been demonstrated to qualify
as Special Form radioactive material. In other words, this includes most
radioactive material shipped, except encapsulated sources with the "Special
Form" certification.
Package. The packaging together with its radioactive contents as presented for
transport.
1) Excepted Package means a packaging together with its excepted
radioactive materials as specified in §§173.421-173.426 and 173.428.
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2) Type A Package means a packaging that, together with its radioactive
contents limited to A1 or A2 as appropriate, meets the requirements of
§§173.410 and 173.412 and is designed to retain the integrity of
containment and shielding required by Part 173 under normal
conditions of transport as demonstrated by the tests set forth in
§173.465 or §173.466, as appropriate.
3) Type B Package means a packaging that, together with its radioactive
contents, is designed to retain the integrity of containment and
shielding required by Part 173 when subjected to the normal
conditions of transport and hypothetical accident test conditions set
forth in 10 CFR 71. There are specific Type B packages, which
include Type B(U) and Type B(M) packages. Their requirements are
specified in §173.403.
4) Industrial Packaging means a packaging that, together with its Low
Section 113
Specific Activity material or Surface Contaminated Object contents,
meets the requirements of §§173.410 and 173.411. Industrial
Packaging is further categorized in §173.411 as Type 1, Type 2, or
Type 3.
Packaging. The assembly of components necessary to ensure compliance with the
packaging requirements of Part 173, Subpart I. It may consist of one or more
receptacles, absorbent materials, spacing structures, thermal insulation, radiation
shielding, service equipment for filling, emptying, venting and pressure relief, and
devices for cooling or absorbing mechanical shocks. The conveyance, tie-down
system, and auxiliary equipment may sometimes be designated as part of the
packaging.
Special Form. Radioactive material which satisfies the following conditions:
1) It is either a single solid piece or is contained in a sealed capsule that
can be opened only by destroying the capsule;
2) The piece or capsule has at least one dimension not less than 5
millimeters (0.2 inch); and
3) It satisfies the test requirements of §173.469. There are other specific
special form encapsulation design exceptions found elsewhere in Part
173.
Surface Contaminated Object (SCO). A solid object which is not itself
radioactive but which has radioactive material distributed on any of its surfaces.
SCO must be in one of two groups with surface activity not exceeding the
following limits:
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1) SCO-I: A solid object on which:
i) The non-fixed contamination on the accessible surface averaged
over 300 cm2 (or the area of the surface if less than 300 cm2) does
not exceed 4 Bq/cm2 (10-4 microcurie/cm2) for beta and gamma
and low toxicity alpha emitters, or 0.4 Bq/cm2 (10-5
microcurie/cm2) for all other alpha emitters;
ii) The fixed contamination on the accessible surface averaged over
300 cm2 (or the area of the surface if less than 300 cm2) does not
exceed 4x104 Bq/cm2 (1.0 microcurie/cm2) for beta and gamma
and low toxicity alpha emitters, or 4x103 Bq/cm2 (0.1
microcurie/cm2) for all other alpha emitters; and
iii) The non-fixed contamination plus the fixed contamination on the
accessible surface averaged over 300 cm2 (or the area of the
surface if less than 300 cm2) does not exceed 4x104 Bq/cm2 (1.0
microcurie/cm2) for beta and gamma and low toxicity alpha
emitters, or 4x103 Bq/cm2 (0.1 microcurie/cm2) for all other alpha
emitters.
2) SCO-II: A solid object on which the limits for SCO-I are exceeded and
on which:
i) The non-fixed contamination on the accessible surface averaged
over 300 cm2 (or the area of the surface if less than 300 cm2) does
not exceed 400 Bq/cm2 (10-2 microcurie/cm2) for beta and gamma
and low toxicity alpha emitters, or 40 Bq/cm2 (10-3
microcurie/cm2) for all other alpha emitters;
ii) The fixed contamination on the accessible surface averaged over
300 cm2 (or the area of the surface if less than 300 cm2) does not
exceed 8x105 Bq/cm2 (20 microcurie/cm2) for beta and gamma and
low toxicity alpha emitters, or 8x104 Bq/cm2 (2 microcurie/cm2)
for all other alpha emitters; and
iii) The non-fixed contamination plus the fixed contamination on the
accessible surface averaged over 300 cm2 (or the area of the
surface if less than 300 cm2) does not exceed 8x105 Bq/cm2 (20
microcurie/cm2) for beta and gamma and low toxicity alpha
emitters, or 8x104 Bq/cm2 (2 microcurie/cm2) for all other alpha
emitters.
Section 114
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Transport Index. The dimensionless number (rounded up to the next tenth) placed
on the label of a package to designate the degree of control to be exercised by the
carrier during transportation.
Type A Quantity. A quantity of radioactive material, the aggregate radioactivity
of which does not exceed A1 for special form radioactive material or A2 for
normal form radioactive material.
Type B Quantity. A quantity of radioactive material greater than a Type A
quantity.
APPLICATION OF REGULATORY REQUIREMENTS
The following is a general discussion of the steps followed to:
• Determine the type and quantity
• Determine the activity and radiation levels
• Package
• Mark, label, and placard
• Surveys of packages and transport vehicles
• Prepare shipping papers.
These steps are for a typical shipment of radioactive material. This discussion is
not all inclusive of every regulatory requirement and is intended only as an
explanation of the major transportation considerations.
Each individual responsible for transfer, packaging or shipping should become
familiar with the regulations and other regulatory documents and establish clear,
step-by-step instructions in the form of procedures for workers to follow.
If the radioactive material is in a physical or chemical form that constitutes a
hazard in addition to the radiological hazard (such as an acid, base, toxic or
flammable substance), additional regulations could apply to the packaging,
shipment and disposal of the material. This type of waste is known as "Mixed
Hazardous Waste." Additional requirements for Mixed Waste are specified in
DOT, EPA, and state regulations.
Radioactive Contents. In order to determine packaging, labeling and other
requirements for shipping radioactive material, the radionuclide content of the
material must be known. This includes the identity and quantity of each isotope.
2.12.03 Describe methods that may be used to determine the radionuclide contents of a
package.
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Identification and quantitative measurement of most gamma emitting isotopes is
fairly simple using gamma energy spectroscopy techniques. It is much more
difficult to identify and measure beta and alpha emitting radionuclides.
Recognizing these problems, the NRC issued technical papers and other guidance
on radionuclide identification techniques. The NRC position papers state that
there are four basic methods which are considered acceptable for radionuclide
identification. These methods are materials accountability, classification by
source, gross radioactivity measurements, and direct measurement of individual
radionuclides.
The materials accountability technique is primarily applicable to wastes and
involves determining the quantity of radioactive material contained within a
volume by comparing the amount of radioactive material entering and exiting a
given process. For example, if the concentration of airborne radioactivity
entering and leaving a HEPA filter is measured and the air volume passing
through the filter is known, the difference can be assumed to be retained in the
filter.
Section 115
The classification by source method involves determining the radionuclide
content through knowledge and control of the source of the material. For
example, a sealed calibration source that was leaking and had to be returned to the
manufacturer could be assumed to contain the same isotope and quantity of
radioactive material as when it was received, provided that source control and
inventory procedures are adequate to ensure traceability of the material (i.e., to
prove that the sealed source being shipped is the same one that was received).
Measurement of gross radioactivity (e.g., based on a dose rate from a container) is
an acceptable method for radionuclide identification provided that:
• The gross radioactivity measurements are correlated to the actual
radionuclides in the material.
• The gross measurement is initially correlated to actual radionuclide
content and periodically verified.
The final acceptable method for determining radionuclide content is by direct
measurement. In this method, individual gamma emitting radionuclides are
directly measured using gamma spectroscopy. Concentrations of other
radionuclides are projected by determining their ratio to the concentration of
gamma emitting radioisotopes. The ratios are usually referred to as scaling
factors. This method is essentially the same as the gross measurement method
except for the quantitative measurement of the individual gamma emitting
isotopes.
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Package Radiation Surveys and Limits
Except as provided in paragraph (b) of §173.441, each package of radioactive
materials offered for transportation must be designed and prepared for shipment,
so that under conditions normally incident to transportation, the radiation level
does not exceed 2 mSv/hour (200 mrem/hour) at any point on the external surface
of the package, and the transport index does not exceed 10.
A package which exceeds 2 mSv/hour (200 mrem/hour) or a transport index of 10
must be transported by exclusive use shipment, and the radiation levels for such
shipment may not exceed the following during transportation:
1) 2 mSv/h (200 mrem/h) on the external surface of the package unless the
following conditions are met, in which case the limit is 10 mSv/h (1000
mrem/h):
i) The shipment is made in a closed transport vehicle;
ii) The package is secured within the vehicle so that its position remains fixed
during transportation; and
iii) There are no loading or unloading operations between the beginning and
end of the transportation;
2) 2 mSv/h (200 mrem/h) at any point on the outer surfaces of the vehicle,
including the top and underside of the vehicle; or in the case of a flat-bed style
vehicle, at any point
on the vertical planes projected from the outer edges of the vehicle, on the
upper surface of the load or enclosure if used, and on the lower external
surface of the vehicle;
3) 0.1 mSv/h (10 mrem/h) at any point 2 meters (6.6 feet) from the outer lateral
surfaces of the vehicle (excluding the top and underside of the vehicle); or in
the case of a flat-bed style vehicle, at any point 2 meters (6.6 feet) from the
vertical planes projected by the outer edges of the vehicle (excluding the top
and underside of the vehicle); and
2.12.04 Describe the necessary radiation and contamination surveys to be performed
on packages and state the applicable limits.
Section 116
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4) 0.02 mSv/h (2mrem/h) in any normally occupied space, except that this
provision does not apply to carriers if they operate under the provisions of a
State or federally regulated radiation protection program and if personnel
under their control who are in such an occupied space wear radiation
dosimetry devices.
For shipments made under the exclusive use provisions, the offeror shall provide
specific written instructions for maintenance of the exclusive use shipment
controls to the carrier. The instructions must be included with the shipping paper
information. The instructions must be sufficient so that, when followed, they will
cause the carrier to avoid actions that will unnecessarily delay delivery or
unnecessarily result in increased radiation levels or radiation exposures to
transport workers or members of the general public.
Packages exceeding 2 mSv/hour (200 mrem/hour) or a transport index of 10 may
not be transported by aircraft.
Contamination Surveys and Limits (Off-site shipments via non-DOE conveyance)
The level of non-fixed (removable) radioactive contamination on the external
surfaces of each package offered for transport must be kept as low as reasonably
achievable. The level of non-fixed radioactive contamination may not exceed the
limits set forth in Table 11 of §173.443 and must be determined by either:
1) Wiping an area of 300 square centimeters of the surface concerned with an
absorbent material, using moderate pressure, and measuring the activity on
the wiping material. Sufficient measurements must be taken in the most
appropriate locations to yield a representative assessment of the non-fixed
contamination levels. The amount of radioactivity measured on any single
wiping material, when averaged over the surface wiped, may not exceed
the limits set forth in Table 11 of §173.443 at any time during transport; or
2) Using other methods of assessment of equal or greater efficiency, in which
case the efficiency of the method used must be taken into account and the
non-fixed contamination on the external surfaces of the package may not
exceed ten times the limits set forth in Table 11 of §173.443, as follows:
2.12.05 Describe the necessary radiation and contamination surveys to be performed
on exclusive use vehicles and state the applicable limits.
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Table 1 - DOT Contamination Limits (Table 11 of §173.443)
Maximum Permissible Limits
Contaminant Bq/cm 2 μCi/cm2 dpm/cm2
Beta and gamma emitters and low toxicity alpha
emitters
0.4
10-5
22
All other alpha emitting radionuclides
.04
10-6
2.2
§173.428 states that a packaging which previously contained radioactive materials
and has been emptied of contents as far as practical, is excepted from the shipping
paper and certification, marking and labeling requirements of this Part 173,
provided that
a) The packaging meets the requirements of Sec. 173.421(a) (2), (3), and (5)
of this §173 Subpart I;
b) The packaging is in unimpaired condition and is securely closed so that
there will be no leakage of radioactive material under conditions normally
incident to transportation;
c) Internal contamination does not exceed 100 times the limits in
§173.443(a);
Section 117
d) Any labels previously applied in conformance with Subpart E of §172 are
removed, obliterated, or covered and the ``Empty'' label prescribed in
§172.450 is affixed to the packaging; and
e) The packaging is prepared for shipment as specified in §173.422.
Contamination Surveys and Limits (On-site and off-site shipments by DOE
conveyance)
49 CFR 172 through 173 describe requirements for inspecting and surveying
packages, containers and transport conveyances prior to off-site transport. The 49
CFR 173 contamination values shall be used as controlling limits for off-site
shipments transported by DOE and non-DOE conveyances. These limits also
apply to on-site transfers of shipments by non-DOE conveyances received from or
destined to off-site locations.
On-site shipments by DOE conveyances may use alternative DOE limits for
contamination, radiation, packaging, etc., provided the alternative is approved.
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DOE Radiological Control Standard, Table 2-2, contamination values may be
used as controlling limits for on-site and off-site transportation when using a DOE
conveyance. When a shipment is received from an off-site destination, in or on a
non-DOE conveyance, the 49 CFR contamination values shall be used when
transfers are made in a DOE conveyance from the on-site receiving location to the
ultimate on-site destination.
Package Marking, Sealing and Labeling.
§173.427 states that for LSA material and SCO required to be consigned as
exclusive use for domestic transportation only, packages are excepted from the
marking and labeling requirements of this subchapter. However, the exterior of
each nonbulk package must be stenciled or otherwise marked ``Radioactive--
LSA'' or ``Radioactive--SCO'', as appropriate, and nonbulk packages that contain
a hazardous substance must also be stenciled or otherwise marked with the letters
``RQ'' in association with the above description.
Except as provided above, LSA material and SCO must be packaged as follows:
1) In an industrial package;
2) For domestic transportation only, in a Type A package. The requirements
of §173.412 (a), (b), (c) and (k) do not apply;
3) For domestic transportation only, in a strong, tight package that prevents
leakage of the radioactive content under normal conditions of transport. In
addition to the requirements of paragraph (a) of §173.427, the following
requirements must be met:
i) The shipment must be exclusive use;
ii) The quantity of radioactive material in each packaging may not
exceed an A2 quantity;
4) For domestic transportation only, in a packaging that complies with the
provisions of 10 CFR 71.52, and is transported in exclusive use; or
5) Any Type B, B(U) or B(M) packaging authorized pursuant to §173.416.
Type A Packages
In addition to meeting the general design requirements prescribed in §173.410,
each Type A packaging must be designed so that–
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a) The outside of the packaging incorporates a feature, such as a seal, that is not
readily breakable, and that, while intact, is evidence that the package has not
been opened. In the case of packages shipped in closed transport vehicles in
exclusive use, the cargo compartment, instead of the individual packages, may
be sealed.
Section 118
b) The smallest external dimension of the package is not less than 10 centimeters
(4 inches).
Type B Packages.
Type B package labeling and marking must meet the following requirements:
a. Follow the same requirements as those described for Type A packages.
b. Follow any additional sealing, labeling, and marking requirements contained
in the NRC Certificate of Compliance for the package or site transport plan.
Surveys of Transport Vehicle. Radiation and contamination surveys should be
performed when an Exclusive Use transport vehicle arrives at the site to ensure
that the vehicle is not exceeding applicable DOT limits. If found to be above
these limits, the vehicle should not be loaded until properly decontaminated and
the owner of the transport vehicle and the site packaging and transportation
department informed. During loading, exclusive use transport vehicles should be
frequently surveyed to avoid the problem of rearranging the load after it is
discovered that the radiation levels are above limits.
Vehicle Radiation Surveys. Radiation surveys should be performed at the
appropriate locations to ensure that the radiation level limits are not exceeded.
Outgoing Vehicle Contamination Surveys. DOT regulations do not specify
contamination limits for transport vehicles other than those designated exclusive
use. It is assumed that if packages loaded onto vehicles are kept within their
contamination limits, the vehicle will be within the package contamination limits.
Contamination surveys of the packages should be conducted at the time of loading
to ensure that they have not become contaminated in storage or through handling.
Even though DOT regulations do not specifically require contamination surveys
for non-exclusive use vehicles, it is good radiological control practice to perform
such surveys to ensure that no contamination is spread to off site areas. Prior to
releasing a radioactive material shipment vehicle, survey the bed of the truck,
floor, seat, and door handles of the cab, controls in cab, tires, and other areas
which could have become contaminated during loading.
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Proper Placarding of Transport Vehicle..
Do not over-label or placard a vehicle unnecessarily. Application of such placard
when the hazard does not exist is a violation of regulations.
Description of Placard. The radioactive placard is diamond shaped with
"Radioactive" in black centered across it on a white background. The upper
portion of the sign has a black
radiation symbol on a yellow background (49 CFR 172.556). The placard must
be fastened to all four sides of the vehicle (49 CFR 172.504(a)).
Location of Placards on Transport Vehicle. Placards must be on all four sides of
the vehicle. If a tractor is disconnected from the trailer, placards must be on all
four sides of the trailer otherwise the front placard can be on the tractor. After the
shipment has been officially received on the receivers property, it is usually
posted in accordance with regular posting (Radiation Area, High Radiation Area,
Contamination Area, etc.)
Inspection Prior to Release of Shipment
(Insert site specific information here)
Documentation. For all shipments, the shipping papers must adhere to the
requirements of 49 CFR 172.200 through 172.204.
Section 119
Verification of Receiving Facility's Authorization to Receive the Material.
10 CFR 30.41 and 10 CFR 70.42 require that before transferring byproduct and/or
special nuclear material, respectively, the shipper must verify that the receiving
facility has a license that authorizes the receipt of the material being shipped.
Although these restrictions only apply to NRC licensees, it is good practice to
perform the same verification prior to shipping radioactive material to other DOE
facilities. Some DOE facilities that normally use only a few isotopes may not
have the proper training or instruments to safely receive and control the material.
It must also not be assumed that other government agencies are exempt from
2.12.06 Identify the proper placement of placards on a transport vehicle.
2.12.07 Identify inspection criteria that should be checked prior to releasing a
shipment at your site.
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NRC regulations and license restrictions. Most Department of Defense facilities
that use radioactive materials, for example, are licensed by the NRC.
VIOLATIONS OF REGULATIONS
Increased public awareness of issues concerning the nuclear industry including
the associated activities of shipping radioactive material and disposing of
radioactive waste, has led to increased political activity in creating new laws,
regulations, and acceptance criteria along with increased inspection activities.
Violations of regulations are considered "serious." Many personnel within the
nuclear industry who are not aware of all of the regulatory requirements are
putting themselves, and others, at risk. Ignorance of the requirements and lack of
attention to detail has lead to many violations. Keeping current with the latest
requirements, periodically reviewing all requirements, creating and enforcing
current procedures to clarify methods of compliance, and inspecting shipments
before they leave the facility is no longer a part time job. Personnel assigned the
responsibility of packaging and shipping radioactive material must realize the
seriousness and consequences of even a minor infraction of the regulations.
Frequent violations of DOT regulations include:
• Leaking packages
• Contaminated packages and vehicles
• Radiation levels exceeding limits in vehicle cabs, underneath vehicles, and
other limits
• Load not securely fastened
• Mechanical deficiencies in the vehicles
• Instructions not provided to carrier for maintaining "exclusive use" of vehicle
• Improper package closure
• Improper packagings for the type or quantity of radioactive material
• Improper or missing markings, labels or placards
• Incomplete and incorrect information on shipping papers.
2.12.08 Describe site procedures for receipt and shipment of radioactive material
shipments.
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RECEIPT OF RADIOACTIVE MATERIAL
10 CFR 835 requires the following:
§835.405 Receipt of radioactive packages.
(a) If packages containing quantities of radioactive material in excess of
a Type A quantity (as defined in 10 CFR 71.4) are expected to be
received from radioactive material transportation, arrangements shall
be made to either:
(1) Take possession of the package when the carrier offers it for
delivery; or
Section 120
(2) Receive notification as soon as practicable after arrival of the
package at the carrier’s terminal and to take possession of the
package expeditiously after receiving such notification.
(b) Upon receipt from radioactive material transportation, external
surfaces of packages known to contain radioactive material shall be
monitored if the package:
(1) Is labeled with a Radioactive White I, Yellow II, or Yellow III
label (as specified in 49 CFR 172.403 and 172.436-440); or
(2) Has been transported as low specific activity material on an
exclusive use vehicle (as these terms are defined in 10 CFR
71.4); or
(3) Has evidence of degradation, such as packages that are
crushed, wet, or damaged.
(c) The monitoring required by paragraph (b) shall include:
(1) Measurements of removable contamination levels, unless the
package contains only special form (as defined at 10 CFR 71.4)
or gaseous radioactive material; and
(2) Measurements of the radiation levels, unless the package
contains a Type B quantity (as defined in 10 CFR 71.4) of
radioactive material.
(d) The monitoring required by paragraph (b) of this section shall be
completed as soon as practicable following receipt of the package,
DOE-HDBK-1122-2009
Module 2.12 Shipment/Receipt of Radioactive Material Study Guide
2.12-18
but not later than 8 hours after the beginning of the working day
following receipt of the package.
(e) Monitoring per § 835.405(b) is not required for packages transported
on a DOE site which have remained under the continuous
observation and control of an individual who is knowledgeable of
and implements required exposure control measures.
It is necessary that packages of radioactive material be expeditiously delivered
and that the existence of a leak be rapidly detected to minimize radiation exposure
to transportation and plant personnel, to minimize the spread of contamination
and to aid in identifying personnel and property that may have been exposed or
contaminated during the transport of the radioactive material. Prompt and careful
inspection of packages containing radioactive material is required by DOE O
460.2A. If the inspection results in even the suspicion that the package may have
been damaged in transit, surveys for removable contamination are required.
(Insert site specific information here)
SHIPMENT OF RADIOACTIVE MATERIAL
(Insert site specific information here)
SHIPMENT EXCEEDING LIMITS
Action When Limits Are Exceeded. If it is known, assumed, or suspected that the
delivering vehicle or packages are contaminated, the delivering carrier, all
intermediate carriers and the shipper must be notified immediately so that
potentially contaminated vehicles can be withdrawn from service and checked.
Loading docks and terminals through which the package passed in transit must
also be surveyed. If any contamination is found on package surfaces, it is
important to check any areas, equipment or personnel who may have become
contaminated handling the package. Depending on the extent of contamination,
the incident may also require notification to DOE Headquarters under the Unusual
Occurrence Reporting system and could result in activation of the Radiological
Assistance Plan. If a package was received from an NRC licensee, the director of
the NRC Inspection and Enforcement Regional Office should also be notified.
(Insert site specific information here)
Section 121
2.12.09 List the actions required at your site if a shipment is received exceeding
radiation or contamination limits.
2.12.10 Describe the proper step-by-step method for opening a package containing
radioactive material at your site.
DOE-HDBK-1122-2009
Module 2.12 Shipment/Receipt of Radioactive Material Study Guide
2.12-19
OPENING PACKAGES OF RADIOACTIVE MATERIAL
It is good radiological control practice to establish, maintain, and follow
procedures for opening packages containing radioactive material.
(Insert site specific information here)
SUMMARY
Radioactive material which is to be transported from one location to another must
be properly packaged, surveyed, labeled and documented. Currently there are
approximately 50,000 weekly shipments of radioactive material in the U.S. Strict
adherence to shipping requirements is requisite to maintain high levels of safety.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-1
Course Title: Radiological Control Technician
Module Title: Radiological Incidents and Emergencies
Module Number: 2.13
Objectives:
2.13.01 Describe the general response and responsibilities of an RCT
during any incident.
→ 2.13.02 Identify any emergency equipment and facilities that are available,
including the location and contents of emergency equipment kits.
→ 2.13.03 Describe the RCT response to a Continuous Air Monitor (CAM)
alarm.
→ 2.13.04 Describe the RCT response to a personnel contamination monitor
alarm.
→ 2.13.05 Describe the RCT response to off scale or lost dosimetry.
→ 2.13.06 Describe the RCT response to rapidly increasing, unanticipated
radiation levels or an area radiation monitor alarm.
→ 2.13.07 Describe the RCT response to a dry or liquid radioactive material
spill.
→ 2.13.08 Describe the RCT response to a fire in a radiological area or
involving radioactive materials.
→ 2.13.09 Describe the RCT response to other specific site incidents (as
applicable).
→ 2.13.10 Describe the response levels associated with radiological
emergencies.
→ 2.13.11 Describe site specific procedures for documenting radiological
incidents.
→ 2.13.12 Identify the structure of the emergency response organization at
your site.
→ 2.13.13 Identify the available offsite incident support groups and explain
the assistance that each group can provide.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-2
→ 2.13.14 Discuss radiological incidents at the plant or other plants, including
cause, prevention, and recommended incident response.
INTRODUCTION
Many people believe "it can't happen here" or "it won't happen to me" and do not
take incident response planning seriously. But, incidents do occur, and
experience has shown that the best response comes from workers who have
prepared themselves with a plan for dealing with incidents. Each incident may be
unique and no plan can be expected to give
an exact solution to every problem, but a step-by-step approach for responding to
a problem will help assure an appropriate response.
REFERENCES:
1. 10 CFR 835 (2007), “Occupational Radiation Protection”.
2. DOE Order 151.1C (2005), “Comprehensive Emergency Management
Systems”.
3. Site-specific emergency preparedness manuals.
RADIOLOGICAL INCIDENTS AND EMERGENCIES
Section 122
A radiological incident is an unplanned event involving radiation or radioactive
materials (part of an emergency). The response taken to an incident is usually
governed by normal procedures.
Emergencies are classified as either an Alert, Site Area Emergency, or General
Emergency, in order of increasing severity, when events occur that represent a
specific threat to workers and the public due to the release or potential release of
significant quantities of radiological and non-radiological hazardous materials.
Classification aids in the rapid communication of critical information and the
initiation of appropriate time-urgent emergency response actions.
Operational Emergencies are major unplanned or abnormal events or conditions
that: involve or affect DOE/NNSA facilities and activities by causing or having
the potential to cause serious health and safety or environmental impacts; require
resources from outside the immediate/affected area or local event scene to
supplement the initial response; and, require time-urgent notifications to initiate
response activities at locations beyond the event scene. In general, to be
considered an Operational Emergency, an event or condition involving the
uncontrolled release of a hazardous material must: immediately threaten or
NOTE: This study guide should be developed using site specific information and
regulatory documents. The following is a recommended format of material.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-3
endanger personnel who are in close proximity of the event; have the potential for
dispersal beyond the immediate vicinity of the release in quantities that threaten
the health and safety of onsite personnel or the public in collocated facilities,
activities, and/or offsite; and have a potential rate of dispersal sufficient to require
a time-urgent response to implement protective actions for workers and the
public. Each DOE/NNSA site/facility must classify Operational Emergencies as
either an Alert, Site Area Emergency, or General Emergency, in order of
increasing severity, when events occur that represent a specific threat to workers
and the public due to the release or potential release of significant quantities of
hazardous materials from DOE/NNSA facilities/activities/operations.
Classification aids in the rapid communication of critical information and the
initiation of appropriate time-urgent emergency response actions.
Causes of radiological incidents and emergencies could be one or more of several
reasons:
• Ignorance
• Forgetfulness
• Oversight
• Unforeseen circumstances
• Communications failures
• Mechanical failures
• Human error
• Natural disasters
Having general guidance on response and a general plan of approach is good
ALARA philosophy, because part of an appropriate response is the risk incurred
by the responders and those involved as well as what is deemed to be an
"acceptable" risk.
GENERAL RESPONSE TO EMERGENCIES
Although Health Physics personnel respond to an emergency using basic
guidelines, an area or site may have specific procedures which have priority over
these guidelines. Health Physics personnel must be familiar with the emergency
procedures applicable to each site and the types of equipment to which they are
assigned. The basic guidelines can then be used in conjunction with the specific
procedures. Even with general or specific guidelines one's actions may change
depending on the severity of an incident or whether one is a first responder, one of
many responders, or a backup person.
Section 123
2.13.01 Describe the general response and responsibilities of an RCT during any
incident.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-4
The basic emergency response guidelines are:
• Define and assess the problem. Typically, personnel at the scene are a
good source of information, however remote instrumentation and other
resources should not be overlooked.
• Attempt to stop the cause of the emergency. No undue risks should be
taken. One must always be aware that careless action may cause them to
become part of the problem.
• Notify facility management and safety personnel. Minor incidents that
can be handled by a single responding person may only require a
telephone call when the opportunity presents itself. If more than one
person is needed for an appropriate response, activation of a site
emergency response network (such as dialing "911") is the manner in
which notification should be given.
• Warn personnel in the area of the emergency. This keeps unnecessary
personnel away from the event site, minimizing their exposure and risk.
• Isolate the area. Install barriers as quickly as possible to establish an
exclusion area. The exclusion area may be very large initially. In
determining the size of the exclusion area, internal and external exposure
rates, potential for criticality, possible spread of radioactive contamination
or other hazardous material, weather conditions, non-radiological hazards,
and security (site security may assist in establishing boundaries). Outside
the exclusion area normal operations may continue. Enlist whatever
resources and personnel that are available to accomplish isolation and be
prepared to help others in this endeavor even if there is no radiological
risk.
• Minimize personnel exposure. During the initial response, remember to
use ALARA concepts, as practical. Plan supplementary operations as
necessary to assure personnel exposure is minimized. All planned
exposures above the occupational limits (5 rem) is voluntary. The
following are guidelines for control of emergency exposures:
- Up to 10 rem for protecting major property and where lower dose
limit is not practicable.
- Up to 25 rem for lifesaving or protection of large populations
where lower dose limit is not practicable.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-5
- Above 25 rem for lifesaving or protection of large populations.
Only on a voluntary basis to personnel fully aware of the risks
involved.
• Secure ventilation. Close entrances, windows, and the supply ventilation
systems as necessary. Remember that most facilities are designed for
proper ventilation and frequently one merely has to ensure that the design
condition are being met such as closing doors, windows, and other
openings that should not be open. One should only alter designed
ventilation if it is obvious that ventilation and improper air flow patterns
are contributing to the incident and impeding bringing it under control.
Even with the conclusion to change ventilation, one should consult with
facility management to determine the impact of changing ventilation on
other activities that may be affected.
• Perform surveys. Health Physics personnel are trained to perform
Section 124
emergency surveys. The types of surveys will vary with the nature of the
emergency. Good quality surveys take time. Do not short cut or speed up
surveys unless a real need such as a medical need exists.
• Initiate the recovery. This includes clean-up operations, decontamination
and moving the exclusion area barricade inward.
The RCT is the Health Physics person on site that has the experience, instruments,
and the responsibility for radiation safety and other personnel will seek them out
for answers. Be prepared to respond with answers, directives, and/or suggestions.
Don't assume others will automatically know what to do. Debriefings for lessons
learned typically obtain good information from the initial responders to incidents.
FACILITIES AND EQUIPMENT
(Insert site specific information here.)
RCT's should always know the resources and equipment available to them in the
area where they are working. These resources include the physical location,
people, equipment, and communications.
2.13.02 Identify any emergency equipment and facilities that are available, including
the location and contents of emergency equipment kits.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-6
Facilities
RCTs should have a thorough knowledge and understanding of processes and
hazards of their assigned facility. This should include a knowledge of the Site
Emergency Response Plan. These plans usually contain information concerning
evacuation routes, staging areas, handling of contaminated personnel, and
information concerning off-site support organizations.
Equipment
Typically, facilities maintain "emergency kits/cabinets" which contain supplies
used in responding to emergencies. These kits/cabinets usually contain smears,
gloves, bags, supplies for posting, dosimetry, respiratory equipment, and a copy
of facility emergency procedures.
RESPONSE TO A CONTINUOUS AIR MONITOR (CAM) ALARM
Airborne radioactivity may be caused by a breach in a system, or resuspension of
particulate radioactivity due to work evolutions such a welding, grinding, or other
heavy work. Indications that an airborne contamination event is occurring include
CAM alarms, air samples exceeding limits, and increasing radiation levels.
Initial Response
• Stop operations that may be causing airborne radioactivity
• Warn others to evacuate
• Secure unfiltered ventilation
• Contact line or facility management for support
Supplementary Actions (re-entry)
• Upon re-entry, don respiratory equipment and protective clothing based on
conditions of the event
• Evaluate the affected area by taking an air sample, measuring radiation
levels, and checking for CAM malfunction
• Obtain additional air samples as necessary to determine boundaries and
maintain access control
• Identify isotope(s) to help determine problem source and protective
measures
2.13.03 Describe the RCT response to a Continuous Air Monitor (CAM) alarm.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-7
• Consider additional ventilation to minimize personnel exposure and
reduce the need for respiratory equipment (HEPA)
• Measure and control surface contamination to minimize the spread of
contamination
• Survey exhaust systems, ventilation filters, and ducts. Have
decontamination performed as necessary to minimize contamination
spread
Section 125
• Evaluate the potential for internal exposure and contact facility dosimetrist
for proper internal dosimetry protocol
• Personnel should be interviewed for information on any off-normal event
which could have caused the alarm
• Take air samples, once operations resume, to verify that the cause of
airborne activity has been corrected
(Insert site specific information here.)
RESPONSE TO PERSONNEL CONTAMINATION MONITOR ALARM
Initial Response
• Instruct affected worker to remain in area (standfast).
• Report to the scene with at least portable instruments for direct surveys
and smear media.
• Perform whole body surveys (frisk) for the appropriate type of radiation
(alpha and/or beta-gamma).
• Take actions to minimize cross-contamination, such as covering or placing
a glove over a contaminated hand.
Supplemental Actions
• Survey affected area to characterize the extent of contamination.
• Suspect an up-take if contamination is verified and survey facial area for
contamination, taking nasal smears or nose blows. If positive, contact
RCT supervision and refer to your facility specific procedures.
2.13.04 Describe the RCT response to a personnel contamination monitor alarm.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-8
• If contaminated, follow-up actions include saving any radioactive material
pertaining to the contamination event, as this may help characterize the
event at a later time.
• Refer to facility specific procedures if contamination persists.
• Document all surveys and estimate skin dose on proper forms. Do not
unduly delay any decontamination efforts by taking too long in
documenting
contamination for skin dose estimates. Remember that dose is being
incurred all the time that the skin is contaminated. Think ALARA
especially in the case of high energy beta emitters.
• Report all confirmed skin contaminations to RCT supervision and refer to
your facility specific procedures if transporting to a medical facility.
• Gather appropriate information for follow-up surveys.
Follow-up actions
Shall be in accordance with the site procedure. These typically include:
• Removal of contaminated clothing or decontamination of minor skin
contamination. Decontaminate skin using mild non-abrasive soap and
tepid water or decon toweletts. Continue decon as long as significant
reduction in activity is occurring after each decon. Do not irritate the skin.
• Verification that personnel monitoring equipment is working properly.
Equipment should not be returned to service until all problems are
resolved. Alarms can be caused by a variety of equipment failures or by
"nuisance" non-work related situations such as environmental radon
resulting from local conditions.
(Insert site specific information here.)
RESPONSE TO OFF-SCALE OR LOST DOSIMETRY
Off-scale Self Reading Personal Dosimeter
2.13.05 Describe the RCT response to off scale or lost dosimetry.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-9
• Assure that the worker is placed in as safe an area as possible (low dose
area) and that the work has been left in a safe condition where possible.
• Alert others working in the area.
• Evaluate the situation. All dose indicated by the dosimeter is assumed to
have been received by the individual until it can be clearly demonstrated
otherwise.
Section 126
• Gather data for dose estimate. Data typically includes work area dose
rates, work activities, worker position, co-worker dose readings, and travel
path conditions. For High exposures, the official permanent dosimetry
(TLD or film badge) should be retrieved for processing.
Lost Dosimetry
For lost dosimetry, typical actions include:
• Individual(s) must leave the area if dosimetry is required.
• Contact RCT supervision for reissue of dosimetry.
Supplemental Actions
• Notify workers supervision
• Restrict additional entries until a dose assessment can be completed
• Consider suspending further work on the RWP until issues are resolved
(Insert site specific information here.)
RESPONSE TO RAPIDLY INCREASING, UNANTICIPATED RADIATION
LEVELS OR AN AREA RADIATION MONITOR ALARM
Initial Response
• Evacuate personnel as quickly as possible to a safe area (low dose area).
• Measure radiation levels in affected area.
2.13.06 Describe the RCT response to rapidly increasing, unanticipated radiation
levels or an area radiation monitor alarm.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-10
• Notify line/facility management. Whether or not to activate a site
emergency response program (such as dialing 911) is determined by the
nature of the incident. Activation usually automatically fulfills this
requirement. When a situation is confusing, not fully understood, or may
not be controllable; over reacting is better than under reacting.
• Evaluate the situation. The best contact is people at the scene.
• Verify postings and boundaries are adequate.
Supplemental Actions
• Verify personnel staging area dose rates are acceptable and check
individual exposures. Notify RCT supervision of results.
• Re-occupy area upon approval of line/facility management.
• Document all surveys using appropriate forms.
(Insert site specific information here.)
RESPONSE TO DRY OR LIQUID RADIOACTIVE SPILL OF KNOWN
MATERIAL AND ORIGIN REQUIRING SWIMS
(Insert site specific information here.)
• STOP the spill. Take appropriate precautions that are dependent on the
situation. All spills are different. Correct the situation immediately if
possible without taking undue risks.
• WARN other personnel. Let people around know what is going on. If the
situation warrants, evacuate the area. Notify your supervisor, facility
management, and emergency response network if appropriate. As before,
whether or not to activate a site emergency response program (such as
dialing 911) is determined by the nature of the incident. Activation
usually automatically fulfills this requirement. When a situation is
confusing, not fully understood, or may not be controllable; over reacting
is better than under reacting.
• ISOLATE the area. Establish boundaries and post the area around the
spill area for exposure and contamination control.
2.13.07 Describe the RCT response to a dry or liquid radioactive material spill.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-11
• MINIMIZE exposure to yourself as well as others. Practice ALARA
principles and use all protective gear available.
• SECURE ventilation by controlling HVAC (heating, ventilation, air
conditioning). Unless one is certain that ventilation is contributing to the
incident, this may involve no more than just ensuring that conditions are
correct for normal designed ventilation.
Section 127
• FOLLOW THROUGH as necessary by starting and collecting air
samples as may be indicated, surveying for contamination, and
decontaminating. The cleanup of major spills may very likely involve
many people and require Radiation Work Permits and ALARA reviews of
activities. Do not try to clean up a major spill by yourself, just keep it
contained and isolated until the entire clean up operation is formulated.
Complete all documentation of surveys and logs.
If you are unsure if you can contain the spill, or if you do not know the nature of
the spill, use the “WIN” process:
• Warn others
• Isolate the area, keep personnel out
• Notify authorities
RESPONSE TO A FIRE IN A RADIOLOGICAL AREA OR INVOLVING
RADIOACTIVE MATERIALS
(Insert site specific information here.)
Typically Radiological Control will supply support to the Fire Department and
will be represented at the Command Post.
2.13.08 Describe the RCT response to a fire in a radiological area or involving
radioactive materials.
2.13.09 Describe the RCT response to other specific site incidents (as applicable).
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-12
RESPONSE TO OTHER FACILITY SPECIFIC INCIDENTS
(Insert site specific information here.)
EMERGENCY RESPONSE LEVELS
(Insert site specific information here.)
ALERT
An Alert shall be declared when events are predicted, are in progress, or have
occurred that result in actual or potential substantial degradation in:
• Level of control over hazardous materials.
• Safety or security of a nuclear weapon, component, or test device that
would not pose an immediate threat to workers or the public.
• Safety or security of a facility or process that could, with further
degradation, produce a Site Area Emergency or General Emergency.
Site Area Emergency
A Site Area Emergency shall be declared when events are predicted, in progress,
or have occurred that result in actual or potential situations that could include one
or more of the following:
• Major failure of functions necessary for the protection of workers or the
public.
• Threat to the integrity of a nuclear weapon, component, or test device that
may adversely impact the health safety of workers in the immediate area,
but not the public.
• Major degradation in level of safety or security of a facility or process that
could, with further degradation, produce a General Emergency.
2.13.10 Describe the response levels associated with radiological emergencies.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-13
General Emergency
A General Emergency shall be declared when events are predicted, in progress, or
have occurred that result in actual or likely situations that could result in one or
more of the following:
• Catastrophic reduction of facility safety or security systems with potential
for the release of large quantities of hazardous materials to the
environment.
• Catastrophic failures in safety or security systems threatening the integrity
of a nuclear weapon, component, or test device that may adversely impact
the health and safety of workers and the public.
DOCUMENTATION OF RADIOLOGICAL INCIDENTS AND EVENT
CATEGORIZATIONS
(Insert site specific information here.)
EMERGENCY RESPONSE ORGANIZATION
(Insert site specific information here.)
Section 128
2.13.11 Describe site specific procedures for documenting radiological incidents.
2.13.12 Identify the structure of the emergency response organization at your site.
2.13.13 Identify the available offsite incident support groups and explain the
assistance that each group can provide.
DOE-HDBK-1122-2009
Module 2.13 Radiological Incidents and Emergencies Study Guide
2.13-14
OFFSITE SUPPORT GROUPS
(Insert site specific information here.)
SITE SPECIFIC LESSONS LEARNED
(Insert site specific information here.)
2.13.14 Discuss radiological incidents at the plant or other plants, including cause,
prevention, and recommended incident response.
DOE-HDBK-1122-2009
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2.13-15
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DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-1
Course Title: Radiological Control Technician
Module Title: Personnel Decontamination
Module Number: 2.14
Objectives:
2.14.01 List the three factors which determine the actions taken in
decontamination of personnel.
→ 2.14.02 List the preliminary actions and notifications required by the RCT
for an individual suspected to be contaminated.
→ 2.14.03 List the actions to be taken by the RCT when contamination of
clothing is confirmed.
→ 2.14.04 List the actions to be taken by the RCT when skin contamination is
confirmed.
→ 2.14.05 List the steps for using decontamination reagents to decontaminate
personnel.
INTRODUCTION
In our work environment, one of the major concerns of radiological control is the
prevention of personnel contamination. When personnel contamination has been
identified, it is the responsibility of the RCTs to perform or oversee the
decontamination of the individual using the best methods available. Frequently,
the RCT is also required to document the decontamination effort and make any
required notifications. This lesson will address the methods used to detect
personnel contamination. In addition, it will address the factors which determine
decontamination actions, the responsibilities of the RCTs and the approved
methods for decontamination of personnel.
References:
(Insert site specific references.)
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-2
PERSONNEL CONTAMINATION
The potential for personnel contamination is normally monitored via one of the
following methods:
External Contamination
• Hand Held Count Rate Meters
• Partial Body Monitors
• Personnel Contamination Monitors.
Internal Contamination
• Whole Body Counts/In Vivo Monitoring
• Bioassay Samples.
When monitoring for external contamination, hand held count rate meters may be
used in one of two ways. Personnel may survey themselves for contamination, or
allow radiological control personnel to conduct the survey for them. The majority
of external contamination surveys are completed using hand held count rate
meters.
Another method of surveying for external contamination is using some type of
contamination monitoring machine. Two basic types of monitors exist, partial
body monitors and whole body monitors. Partial body monitors, such as hand-
and-shoe monitors, a half body monitor, or a portal (walk through) monitor,
monitor only a portion of the body. As such, partial body monitors should only
be utilized for spot-checking for personnel contamination. To conduct a whole
body survey, a personnel contamination monitor that surveys the entire body
should be used.
Section 129
Internal contamination may monitored in one of two ways. The first method
includes whole body counts and specific organ counts (lungs, thyroid, etc.). This
type of internal monitoring is called in vivo monitoring. The other type of internal
contamination monitoring uses some sample from the person to determine the
presence of contamination. Methods may include urinalysis, fecal analysis, blood
sampling and others. These methods are called in vitro monitoring.
In some cases, the presence of contamination on a worker will be assumed based
on the work situation. The following list provides some examples of work
situation that may result in personnel contamination.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-3
• Exposure of the worker to known contaminated liquids
• Exposure of the worker to airborne contamination without proper
respiratory protection.
• Improper work practices within removable contamination areas such as:
- Improper removal of protective clothing or devices
- Improper work practices with contaminated materials
- Failure to follow radiological control requirements set for work
being performed
- Unknowingly working with material discovered to be
contaminated.
BASIC FACTORS AFFECTING DECONTAMINATION
Once the RCT determines the worker is contaminated, the actions taken will be
controlled by three basic radiological control factors. These factors include:
• Physical condition of the worker
• Location of the contamination on the worker
• Activity of the nuclide(s) present.
Primary consideration should be given to the physical condition of the worker.
All actions taken by the RCT will be based on the workers physical condition.
The major concern should be whether or not the worker has a serious injury.
When a worker sustains a serious injury, the primary concern is the first aid or
assistance the worker needs. When a worker sustains an injury, the extent of the
injury needs to be determined. Conditions that should be investigated include
open/puncture wounds, bruises, sprains, strains and fractures.
Once the physical condition of the worker has been identified, the location of the
contamination needs to be determined. Questions requiring particular attention to
answer include:
• Is contamination localized on general skin surface?
• Is contamination located on or near a body orifice?
• Is contamination located near a break in the skin?
2.14.01 List the three factors which determine the actions taken in decontamination of
personnel.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-4
• Is there a skin condition present in the vicinity of the contamination?
• Is the contamination on the clothing?
Finally, the amount and type of contamination needs to be determined. This will
include a determination of the type of activity (alpha, beta or gamma) and saving
some type of sample for laboratory analysis.
SUSPECTED CONTAMINATION
(Insert site specific material here)
When an RCT is notified of a contaminated or potentially contaminated
individual, the individual should be told to remain where they are and the
following actions should be accomplished.
Obtain Instruments and Proceed To Location: The RCT should obtain the
necessary instrumentation and proceed to the location of the individual with
suspected contamination.
Section 130
Assess Conditions: Arriving at the location, the RCT should make a quick
assessment of the condition of the individual and the possibility spreading
contamination. If injury is evident, the RCT must immediately notify, or
designate someone to notify, the Radiological Control supervisor. If the
individual is not injured, a preliminary survey will give the RCT a quick
indication of the extent and locations of contamination that may be present. This
quick assessment is to determine the immediate course of action and whether
additional help is needed or an emergency must be declared.
While performing the assessment survey, the RCT may question the individual to
gain information regarding the event that may have caused the contamination.
The RCT may elect to notify the Radiological Control supervisor to ask for
additional support if, in the judgement of the RCT, the support is needed. For
events where there is cause to believe an internal deposition may have occurred or
there is extensive contamination, a second RCT may necessary to record readings
and to take and count smears (including nose blows or nasal smears). Another
example of when an RCT could ask for additional support would be if there were
indications that contamination control had been lost in an area frequented by other
workers. A second RCT might be needed to ensure immediate posting, traffic
control, and to investigate the radiological conditions.
High levels of contamination found on the skin or clothing during the preliminary
survey should be removed immediately to reduce dose. Securely bag and retain
removed contamination for analysis by dosimetry. Actions for lower levels of
2.14.02 List the preliminary actions and notifications required by the RCT for an
individual suspected to be contaminated.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-5
confirmed contamination on skin or clothing may proceed in a more methodical
manner as described below.
Perform A Personnel Survey: After the quick assessment survey, a detailed
whole body survey should be performed of the entire exposed surface area
(protective clothing if worn, personal clothing and/or skin) for both alpha and
beta-gamma contamination. Starting at the head and proceeding to the feet, pay
particular attention to the following areas:
contaminated area (if known) , nose and mouth, hands, skin folds,
buttocks, knees, feet
Use the following guidelines for the survey:
1. Verify that the instrument is in service (e.g., turn the monitor on, check the
battery and source response) set it to the proper scale so that the audio
output can be heard during the survey.
The instrument must have also passed a daily source check, and have a
calibration date that has not expired.
2. Hold the probe less than 1/2 inch from the surface being surveyed for beta
and gamma contamination, and approximately 1/4 inch for alpha
contamination. Do not touch the probe to the area being surveyed to
preclude contaminating the probe.
3. Move the probe slowly over the surface (approximately 2 inches per
second).
4. If the count rate increases during the survey, pause for 5 to 10 seconds
over the area to provide adequate time for instrument response.
5. If the count rate increases to a value greater than a pre-established
contamination limit or the instrument alarms then the presence of
contamination is confirmed. If confirmed, control, decontaminate and/or
notify radiological control personnel (while remaining in the area).
Section 131
6. The whole body survey should take several minutes. Do not hurry the
survey. Take all the time necessary to complete the survey.
Using portable or semi-portable count rate type instruments, an individual may
receive an unconditional personnel survey release if contamination is not detected
while performing an entire body survey.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-6
Notify Appropriate Personnel: If extensive whole body contamination is found or
facial contamination is present, Radiological Control and medical personnel
should be notified.
Control Contamination: If the contaminated individual must be moved to another
location (e.g. hospital or decontamination facility), contain the contamination as
much as possible before allowing the person to move by:
1. Removing and bagging shoes and/or covering feet with plastic shoe
covers/booties.
2. Covering the hands of the individual with gloves, preferably "Surgical"
gloves.
3. Donning a clean set of Anti-C's over contaminated clothes or merely
wrapping the individual with any covering.
CONTAMINATED CLOTHING
(Insert site specific material here)
Clothing contamination should be treated just as seriously as skin contamination
until the clothing has been removed and it has been verified that no skin
contamination is present. When the clothing of an individual is found
contaminated, advise the individual to refrain from moving around or touching the
contaminated area and follow the specified procedures for decontamination. At a
minimum, the following should be accomplished.
Control Contamination: Contain and remove areas of gross contamination
including hot particles by pulling off with tape or cutting out the area and securely
bagging the contamination.
Remove Clothing: Carefully remove and securely bag all contaminated clothing.
Properly store and save the contaminated clothing worn by the individual for
analysis by dosimetry if there is skin contamination or a possible uptake of
radioactive material.
Resurvey the Individual: Perform a personnel whole body survey after removal
of contaminated clothing to determine that the individual is not recontaminated.
2.14.03 List the actions to be taken by the RCT when contamination of clothing is
confirmed.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-7
1. If contamination persists consider moving to a decontamination facility.
2. Assess potential for internal deposition (airborne, puncture) by surveying
outside and inside of masks, surveying facial area, and taking mouth or
nasal smears.
SKIN DECONTAMINATION
(Insert site specific material here)
When the skin of an individual is found contaminated, follow the specified
procedures for decontamination. Stop the decontamination effort if the skin
becomes irritated or the individual complains of discomfort. At a minimum, the
following should be accomplished.
Remove High Levels of Contamination: Hot particles and high levels of
contamination should be removed as soon as possible. The time spent to
determine the activity and area of contamination should be minimized when high
doses are possible.
Notify Radiological Control: Notify Radiological Control and other personnel as
may be needed for dose assessment and decontamination.
Decontaminate if Appropriate: Determine the condition of the skin (cuts, sores,
abrasions, irritations, etc.) and decontaminate if appropriate. Treatment of
contaminated skin with skin conditions (including wounds) is usually reserved for
medical personnel. Flushing minor wounds with plain tepid water may be
permitted.
Section 132
Whole skin can be decontaminated by wiping with moist towelettes, flushing with
plain tepid water, or washing with mild non abrasive soap and tepid water. Tape
should only be used in areas where there is minimal hair and hair can only be
trimmed with permission of the individual.
Retain particles or other samples of contamination for analysis and dose
assessment by Dosimetry.
Assess the Possibility of Internal Contamination: Assess potential for internal
deposition (airborne, puncture) by surveying outside and inside of masks,
surveying facial area, and taking mouth or nasal smears.
2.14.04 List the actions to be taken by the RCT when skin contamination is confirmed.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-8
DOCUMENTATION
After decontamination has been completed, it is essential that the proper
documentation is completed for proper records.
(Insert site specific material here)
Typical documentation includes an estimate of the skin area and location affected
and the activity involved. In addition, a description of the decontamination
process including levels and iterations is also required.
DECONTAMINATION REAGENTS
(Insert site specific material here)
Generally the following applies:
• Soaps and detergents emulsify and dissolve contamination and are
frequently all that are needed for decontamination of skin. Decon
towelettes are also used for minor decontaminating. The first attempts for
decontaminating should always begin with the least irritating agent (e.g.
soap and water) before proceeding to stronger techniques. Sweating may
also be used to dislodge contamination by applying gloves, wraps, or
warm baths.
• Sticky tapes may also be used but the potential for irritating the skin must
be kept in mind. It is a common mistake to under-estimate the potential
for skin irritation until too late. Particular care should be taken on the
more sensitive and thin skin areas. At times, if the skin becomes irritated,
decontamination may have to wait until the skin heals before proceeding
with decontamination.
• Stronger and more abrasive soaps (Tide, Clorox, or cornmeal) may
dislodge the contamination but are generally used by medical personnel
because of their potential for damaging the skin.
• Stronger chemical techniques such as those using Potassium
Permanganate (KMnO4), Sodium Bisulfite (NaHSO3), DTPA (as a wash),
or CaDTPA (as a wash) are not often needed, but when they are, they
should be used only by trained medical personnel.
2.14.05 List the steps for using decontamination reagents to decontaminate personnel.
DOE-HDBK-1122-2009
Module 2.14 Personnel Decontamination Study Guide
2.14-9
SUMMARY
In this lesson we have covered the basic principles of personnel decontamination.
Our main subjects are the actions taken in the event of potential personnel
contamination, notifications required in the event of personnel injury, proper
methods for identification and location of contamination, proper action to be
taken once contamination has been confirmed and the approved methods for
decontamination of personnel. Also discussed were the types of reagents utilized
for personnel decontamination, and the precautions associated with each.
DOE-HDBK-1122-2009
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-1
Course Title: Radiological Control Technician
Module Title: Radiological Considerations for First Aid
Module Number: 2.15
Section 133
Objectives:
2.15.01 List the proper steps for the treatment of minor injuries occurring
in various radiological areas.
2.15.02 List the requirements for responding to major injuries or illnesses
in radiological areas.
2.15.03 State the RCT's responsibility at the scene of a major injury in a
radiological area after medical personnel have arrived at the scene.
→ 2.15.04 List the requirements for treatment and transport of contaminated
injured personnel at your facility.
INTRODUCTION
"Standard first aid is applied prior to contamination control whenever it is
considered to have life-saving value, or is important to the patient for relief of
pain or prevention of disability. It is the obligation of all who assist a patient to
render such aid within the limits of their training and qualifications."
References:
1. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
2. "Operational Health Physics Training" - H. J. Moe.
DOE-HDBK-1122-2009
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-2
MINOR INJURIES OCCURRING IN RADIOLOGICAL AREAS
Render first aid as needed.
Survey for contamination. The survey should include clothing, exposed skin, and
any wounds. RCTs are responsible for determining whether wounds are
contaminated, and to then advise Medical.
Decontamination is then performed as necessary. Decontamination of wounds or
broken skin by RCT's is generally limited to flushing with tepid water. Complete
decontamination of wounds or broken skin is generally done by Medical
personnel.
Inform Medical of the facts regarding injured's name and condition, location, and
degree of contamination so that appropriate treatment may be administered.
Get to Medical Aid. If the injury is minor and the person is not contaminated,
someone should escort the person to the nearest First Aid Station for treatment. If
the injury is minor and the person is contaminated, the affected area should be
covered, and they should be taken to the nearest personnel decon room or
emergency decon station, and medical assistance should be requested at that
location. Depending on the minor injury and local procedures, activation of an
emergency response may be appropriate which would provide medical aid.
MAJOR INJURIES OCCURRING IN RADIOLOGICAL AREAS
If first to arrive on the scene, administer first aid to the injured. (As always, first
aid should be administered only to the extent that an individual is trained and
qualified to perform.) The first consideration is getting appropriate medical
treatment to the patient, either in the radiological area or through evacuation from
the radiological area. This should be considered prior to first aid measures only if
leaving the person in the area for a short time would further endanger the injured's
and the rescuer's health and safety.
2.15.01 List the proper steps for the treatment of minor injuries occurring in various
radiological areas.
2.15.02 List the requirements for responding to major injuries or illnesses in
radiological areas.
DOE-HDBK-1122-2009
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-3
Contamination levels would rarely be the cause for immediately evacuating, or
delaying first aid to, a seriously injured person from an area prior to first aid.
• A contaminated live person is, in every case, preferable to a clean
Section 134
deceased person.
• If the person administering first aid becomes contaminated, remember that
the rescuer can be decontaminated much easier than the injured person can
be brought back to life if first aid was delayed to enable the rescuer to
avoid becoming contaminated.
Airborne radioactivity would rarely be the cause for immediately evacuating, or
delaying first aid to, a seriously injured person from an area prior to first aid.
• Remember that a live patient with some internal contamination is always
preferable to a deceased person with no internal contamination.
Radiation levels could require evacuation to be the first consideration.
Consideration must be given to both the injured and the rescuer(s) in this instance.
If treating the person in the location would expose them or the rescuer(s) to a
hazardous radiation dose, movement out of the area would then be done first.
• This is a judgment call, depending upon the nature of the injuries, the
radiological conditions, the location of the injured, etc. There is no
"magic number" for a dose rate that would require immediate movement
regardless of injury.
Get help to the scene. The timing and method of doing this will depend on the
extent of the injuries, the location, how many people are present, etc.
Survey the injured person(s). This should include the clothing, exposed skin, and
any wounds. If the injured is in an area with high radiation levels, the RCT must
be able to provide an estimated equivalent dose to Medical. Even if the levels are
not high enough to warrant immediate evacuation, the total dose to the injured
individual may dictate what medical treatment is given. This would require a
knowledge of the radiation dose rates in the area, and determination (or estimate)
of the length of time that the person was exposed to these levels.
Assist Medical personnel with treatment, transportation, and decontamination.
For a seriously injured and contaminated person, transportation would be by
ambulance. For transport of contaminated person(s), the RCT would accompany
the injured in the ambulance. Necessary measures should be taken to reduce or
eliminate the spread of contamination on the way. If the patient has gross
transferable contamination, consideration should be given to wrapping the injured
person in a blanket to contain the contamination. Since this could prevent or
DOE-HDBK-1122-2009
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-4
delay treatment, or in some cases aggravate the injuries, it would only be done
with the concurrence of Medical personnel.
Control movement of personnel between rooms at the medical facility specific to
prevent the spread of contamination.
Provide containers and instruct patients regarding the collection of bioassay
samples. Collect specimens of any blood, excised tissue, etc.
Survey all clothing, equipment and instruments used in the medical facility and
transport vehicle. Recommend decontamination or disposal of items as necessary.
Some typical problems and concerns arise in hospital situations. Portable X-ray
machines, used extensively in emergency room settings, cause a problem if being
brought into a room with a contaminated patient. As soon as the X-ray has been
taken, the hospital staff will usually want to remove the machine from the room
ASAP. Waste materials, contaminated materials, radioactive materials or
particles, etc. removed from the patient may begin to pose a radiation hazard of
their own if allowed to concentrate or remain in the immediate vicinity of the
patient and treatment personnel. Accumulating radioactive material in the
treatment area can also cause problems with monitoring for dose rates and
contamination levels because of the increased background in the area.
Section 135
INTERFACE OF RCT AND MEDICAL PERSONNEL
After the initial response and first aid, the primary duty of the RCT will be with
radiological concerns, the primary concern of Medical personnel will be the
patients' medical condition and treatment. These two concerns must be balanced
against one another keeping the best interest of the patient in mind.
The RCT must be careful not to make medical decisions or judgments that he/she
is not qualified to make. However, the RCT will be primarily responsible for
decisions involving radiological concerns.
The RCT should advise medical personnel of radiological conditions and
precautions and make decisions concerning the radiological protection of the
personnel on the scene.
2.15.03 State the RCT's responsibility at the scene of a major injury in a radiological
area after medical personnel have arrived at the scene.
2.15.04 List the requirements for treatment and transport of contaminated injured
personnel at your facility.
DOE-HDBK-1122-2009
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-5
REQUIREMENTS FOR THE TREATMENT AND TRANSPORT OF
CONTAMINATED INJURED PERSONNEL
(Insert site specific material here.)
The following is typical of good Health Physics practices.
If the RCT is the first on the scene and there are injured contaminated personnel,
the injuries always take precedence over contamination control. The RCT should
only administer first aid that they are trained to perform. The RCT should get
help as quickly as possible.
When help arrives, the RCT should assist medical personnel. If the contaminated
individual has to be transported to the plant hospital, an RCT usually accompanies
the injured person to the area. Prior to transporting, preliminary cleanup of
transferable contaminants are to be done to the extent that the patient's injuries
permit. If it is not possible to do a preliminary cleanup, wrap the patient in a
sheet or blanket to limit the spread of contamination.
Sometimes the injury may need a more extensive evaluation and the individual
may have to be transported to an area hospital. The individual should have been
stabilized and if possible, contaminated clothing removed and skin deconned prior
to transporting. If this is not possible the RCT, or other Health Physics
representative, usually accompanies the individual to the hospital.
After the needs of the contaminated/injured person have been met, all areas and
items that they came in contact with will have to be surveyed for contamination.
Other RCT's are typically needed to assist in these situations.
The RCT is responsible for documenting all pertinent information about the
incident and results of the surveys taken. The medical staff may be able to survey
for contamination, but the RCT still needs to survey and complete the
documentation. The RCT should make sure all documentation is thorough and
accurate for legal reasons.
SUMMARY
It is imperative that the RCT be prepared to respond in the case of injuries or
illnesses occurring in radiological areas. In cases of minor injuries, the primary
concern will normally be the removal of contamination and preventing the spread
of it. However, in the event of major injuries involving large does of radiation or
contamination patients, first aid and life saving measures will normally take
precedent, even at the expense of routine contamination control measures.
DOE-HDBK-1122-2009
Section 136
Module 2.15 Radiological Considerations for First Aid Study Guide
2.15-6
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DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-1
Course Title: Radiological Control Technician
Module Title: Radiation Survey Instrumentation
Module Number: 2.16
Objectives:
2.16.01 List the factors which affect an RCT's selection of a portable
radiation survey instrument, and identify appropriate instruments
for external radiation surveys.
→ 2.16.02 Identify the following features and specifications for ion chamber
instruments used at your facility:
a. Detector type
b. Instrument operating range
c. Detector shielding
d. Detector window
e. Types of radiation detected/measured
f. Operator-adjustable controls
g. Markings for detector effective center
h. Specific limitations/characteristics
→ 2.16.03 Identify the following features and specifications for high range
instruments used at your facility:
a. Detector type
b. Instrument operating range
c. Detector shielding
d. Detector window
e. Types of radiation detected/measured
f. Operator-adjustable controls
g. Markings for detector effective center
h. Specific limitations/characteristics
→ 2.16.04 Identify the following features and specifications for neutron
detection and measurement instruments used at your facility:
a. Detector type
b. Instrument operating range
c. Types of radiation detected/measured
d. Energy response
e. Operator-adjustable controls
f. Specific limitations/characteristics
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-2
INTRODUCTION
External exposure controls used to minimize the equivalent dose to personnel are
based on the data taken with portable radiation survey instruments. An
understanding of these instruments is important to ensure the data obtained are
accurate and appropriate for the source of radiation. This lesson contains
information about widely used portable radiation survey instruments.
Many factors can affect how well the measurement reflects the actual conditions,
such as:
• Selection of the appropriate instrument based on type and energy of
radiation, radiation intensity, and other factors.
• Correct operation of the instrument based on the instrument operating
characteristics and limitations.
• Calibration of the instrument to a known radiation field similar in type,
energy and intensity to the radiation field to be measured.
• Other radiological and non-radiological factors that affect the instrument
response, such as RF fields, radioactive gases, mixed radiation fields,
humidity and temperature.
References:
1. Radiation Detection and Measurement, Glenn F. Knoll.
2. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
3. Operational Health Physics, Harold J. Moe.
4. ANSI N323A.
NOTE: The text is provided for some commonly used instruments. The facility must adjust
text as necessary for instruments used at each site. Text added for specific instruments used at
the facility must, at a minimum, cover material required by the objectives.
2.16.01 List the factors which affect an RCT's selection of a portable radiation survey
instrument, and identify appropriate instruments for external radiation
surveys.
DOE-HDBK-1122-2009
Section 137
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-3
FACTORS AFFECTING INSTRUMENT SELECTION
As discussed, the selection of the proper instrument is critical to ensure the data
obtained are accurate and appropriate. The instrument is selected based on the
characteristics and specifications for that instrument as compared to the required
measurements. Several factors should be considered when selecting the
instrument.
• Type of Data Required
Distinguish clearly between external radiation surveys (lesson 2.16) and
contamination monitoring (lesson 2.17). External radiation surveys
require an instrument that reads R/hr, mR/hr, rem/hr, mrem/hr, etc., rather
than counts per minute, etc.
• Measurement of the True Equivalent Dose
Ion chambers (which read current instead of counting pulses) have the
flattest energy response. Ion chambers are closest to being tissue
equivalent. Generally, the best choice for external beta-gamma surveys is
an ion chamber.
• Type of Radiation to be Measured
Ion chambers measure beta and gamma. For neutrons, choose a rem ball
(NRD). Alphas are not measured in an external radiation survey, since
they do not penetrate the skin (7 mg/cm2, see lesson 1.07.10).
• Intensity of the Radiation (exposure or dose rate)
For high radiation fields (>5 R/hr) use an extendible instrument
(Teletector) if this is "reasonably achievable" (ALARA).
• Energy of the Radiation to be Measured
Low energy radiation will not penetrate either the skin or the window of
most external radiation instruments. GM detectors over-respond to low
energy gammas. Most instruments under-respond to high energy
neutrons.
• Environmental Factors
Ion chambers are usually vented to air, so radioactive gases or high
humidity affect the instrument response.
• Procedures
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-4
If all else fails, read the instructions!
Preoperational Check
Once the proper type of instrument has been identified, a pre-operational check is
essential and must be performed in accordance with appropriate procedures.
• Physical Damage
Perform a physical inspection of the instrument by checking for obvious
physical defects or damage, especially of the probe, and replace the probe
or cable if necessary.
• Calibration Sticker
Verify the instrument is calibrated and has not exceeded the calibration
due date.
• Battery
Perform a battery check to verify the battery condition is within the
acceptable range. Change the batteries if necessary.
• Zero
Perform a zero adjustment for the meter needle, if applicable (e.g. for ion
chambers).
• Source Check
Perform a source response check as required by the procedures.
Instrument Selection General Principles
To ensure the proper selection and operation of instruments, the instrument
operator must understand the operating characteristics and limitations of each
instrument available for use.
There are general principles which apply to the specific instruments described in
the following sections.
• Detector Type
Ion chambers have the flattest energy response. Ion chambers are closest
to being tissue equivalent.
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-5
GM detectors over-respond to low energy gammas
Special detectors are used for neutrons
Section 138
• Instrument Operating Range
External radiation measuring instruments read in R/hr, rad/hr, or rem/hr.
In contrast, instruments designed for measuring contamination read in
cpm.
Extendible instruments are generally appropriate for high radiation fields.
• Detector Shielding
Large amounts of shielding are not practical with a portable instrument,
but some probes incorporate a small amount of shielding to reduce the
background. Many external radiation survey instruments incorporate a
sliding "beta shield". Note that this also shields low energy gammas.
• Detector Window
External radiation instruments generally have windows that are about as
thick as human skin (7 mg/cm2). The reason for this is: if the radiation
does not penetrate this window then it does not penetrate skin, and so it
does not contribute any external dose. In contrast, contamination
monitoring instruments have thinner windows.
• Types of Radiation Detected/Measured
Ion chambers have a flat energy response for gammas. Ion chambers are
closest to being tissue equivalent. They are also good for betas, but a
correction factor may be needed.
Tube shaped GM detectors are designed so that the walls are close to the
detector gas. Gamma interactions in the walls are important. A well
designed detector wall can partially compensate for the over-response to
low energy gammas. They are designed primarily for gammas, and also
measure betas if the window is not too thick.
Pancake shaped GM detectors have side walls separated from the gas.
They are good for betas, but have a low efficiency for gammas because
very few gammas hit the side walls.
Gas proportional detectors distinguish between alphas and betas. They
often discriminate against (reject) betas and gammas.
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-6
ZnS scintillation detectors only detect alphas.
NaI scintillation detectors are generally used for gammas.
Neutron detectors are very specialized.
• Operator Adjustable Controls
Portable instruments generally have a battery check.
Ion chambers generally have a zero adjustment.
• Markings for Effective Detector Center
External radiation surveys are generally taken at 30 cm (except for
transportation, see lesson 2.12). It is not always obvious what point on the
detector should be 30 cm from the source, so most detectors mark the
effective center.
The effective center of the detector, as defined in ANSI N323, is the point
within the detector that produces, for a given set of irradiation conditions,
an instrument response equivalent to that which would be produced if the
entire detector were located at that point. The effective center can be
thought of as the point in the detector where the measurement of the
radiation intensity is taken. Portable radiation survey instruments are
calibrated in a uniform field of radiation larger than the volume of the
detector, so that the same radiation intensity is seen throughout the
detector. Therefore, the reading "taken" at the effective center represents
the rate value in all portions of the detector. If the radiation field over the
whole detector is not uniform, the exposure rate will not be uniform over
the entire detector volume. For non-uniformly irradiated detectors, the
displayed value, as "taken" at the effective center, will not reflect the
actual exposure rate value and a correction factor may be appropriate.
Section 139
2.16.02 Identify the following features and specifications for ion chamber instruments
used at your facility:
a. Detector type
b. Instrument operating range
c. Detector shielding
d. Detector window
e. Types of radiation detected/measured
f. Operator-adjustable controls
g. Markings for detector effective center
h. Specific limitations/characteristics
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-7
EBERLINE RO-2 and RO-3
The Eberline RO-2, RO-3 series of instruments are portable, air-vented ion
chamber instruments used to detect and measure gamma, X-ray, and beta
radiation. Technical specifications for the RO-3 are similar to the RO-2.
Detector Type
The ion chamber is a phenolic, or plastic cylinder of 3 in. diameter and 12.7in3
(208cm3) volume, with one end covered by a Mylar window. The fill gas is air,
vented to atmosphere through a desiccant pack.
The ion chamber detector is closer to tissue-equivalent than most types, allowing
the instrument to assess the exposure rate to human tissue. The detector is
approximately tissue equivalent because the materials used for construction have
an effective atomic number Z close to that of tissue at 7.5. "Tissue equivalent"
means that the detector responds the same as human soft tissue. No detector is
perfectly tissue equivalent, but a well designed ion chamber is close enough for
most work.
Although the detector is not as sensitive as a GM, it is the detector of choice for
assessing exposure because of its close correlation to the energy deposited in
human tissue by radiation.
The RO-2 series instruments are operated in the current mode, which is the mode
that averages the individual pulse heights per unit time. Individual pulse
information is lost; therefore, the electrical signal will not supply information
about the type and energy of the individual radiation interactions. However, small
pulses, which would be lost in the pulse mode, are averaged along with the other
interactions.
Instrument Operating Ranges
The instrument range of the Model RO-2 is 0 - 5000 mR/hr. The readings are
expressed in roentgen, since the measurement is made in air.
DOE-HDBK-1122-2009
Module 2.16 Radiation Survey Instrumentation Study Guide
2.16-8
The settings are as follows:
RO-2 Ranges
0-5 mR/hr
0-50 mR/hr
0-500 mR/hr
0-5,000 mR/hr
Detector Shielding
The sliding beta shield is made of phenolic as follows:
• RO-2 shield: 400mg/cm2 (1/8 in. thick) mounted on the case.
The active volume of the detector is shielded from the side by the detector wall
and the instrument case, and from the bottom by the movable beta shield and two
layers of window. The detector wall is 200 mg/cm2 and the 0.13 cm aluminum
case is about 345 mg/cm2.
Detector Window
The materials and density-thickness value of the two windows, one on the case
and one on the detector, for the Model RO-2 and RO3 are as follows:
• RO-2 windows: 7 mg/cm2 total; two Mylar windows 3.5mg/cm2 (1 mil)
each.
• RO-3 window: 3.5 mg/cm2 total; one window of 1 mil Mylar.
Types of Radiation Detected/Measured
The RO-2 instrument is designed to measure gamma, X-ray, and beta radiation
but will respond to (not measure) neutron radiation. Although an ionization
chamber would respond to alpha radiation, the Mylar windows and the air gap
between the two windows eliminates any possibility of an alpha response.
Section 140
The RO-2 measures photon radiation within ±20% for photon energies from 12-
keV to 7MeV (beta shield open). The minimum energy increases to 25keV if the
shield is closed, and to about 40keV through the side of the instrument. Because
of the thinner window, the RO-3 measures photons from 8-keV.
The RO-2 measures beta radiation >70keV with the beta shield open. A beta
correction factor may be appropriate in some situations.
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Operator-Adjustable Controls
RO-2 range switch with OFF, ZERO, and BATT checking positions.
ZERO position works in conjunction with ZERO knob to electronically zero the
meter. BAT1 and BAT2 positions check the two batteries used to power the
instrument circuitry.
Markings for Detector Effective Center
The Effective Center markings on the RO-2 are the "dimples" or depressions on
the sides and front of the instrument case.
Specific Limitations\Characteristics
The response time for the RO-2 series of instruments is 5 seconds to reach 90% of
the full value.
High humidity or moisture can cause leakage currents in the detector and cause
erratic meter readings. The detector is vented through a silica gel desiccant, or
drying medium, contained in a plastic box. The desiccant can become saturated
and will need replacement if the crystals start to turn clear or pink instead of the
normal blue color.
The detector is vented to atmosphere; therefore, any change in atmospheric
density changes the air density in the detector. An increase in atmospheric
pressure will cause an increase in air density in the detector and cause a higher
response. If the RO2 is calibrated in Los Alamos (7000 ft) and then used at sea
level, the response will be 30% high. A change in response of about 10% will
occur if the instrument was calibrated at room temperature and used in an
environment that is different by about 50 ΕF.
Because the detector is vented to atmosphere, radioactive gases could enter the
detector and cause a reading.
BICRON RSO-50 AND RSO-500 INSTRUMENTS
The Bicron RSO-50 and RSO-500 instruments are portable air-vented ion
chamber instruments used to detect and measure gamma, X-ray and beta
radiation. The Bicron RSO series of instruments are very similar in design and
construction to the Eberline RO-2 series of instruments.
Detector Type (identical for both models)
• Operated as an ionization chamber.
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• A phenolic, or plastic, cylinder of 3 in. diameter and 12.7 in3 (208 cm3)
volume with one end open but covered by a Mylar window.
• Fill gas - air (vented to atmosphere through a silica gel desiccant pack).
The Bicron RSO series instruments are operated in the current mode, or the mode
that averages the individual pulse heights per unit time.
Instrument Operating Range
The instrument ranges of the two models are as follows:
Detector Shielding
The active volume of the detector is shielded from the side by the detector wall
and the instrument case and from the bottom by the movable beta shield and two
layers of window. Detector wall is 200 mg/cm2 and the 0.13 cm aluminum case is
about 345 mg/cm.
Detector Window
The materials and density-thickness value of the two windows, one on the case
and one on the detector, are the same for both models.
Section 141
• RSO windows - 7 mg/cm2 total, both windows are Mylar of 5 mg/cm2
each.
The sliding beta shield is made of phenolic and the density-thickness value is the
same for both models.
• RSO shield - 400 mg/cm2 (1/8 in. thick) and is mounted externally on the
case.
RSO-500 Ranges
0-0.5 R/hr
0-5 R/hr
0-50 R/hr
0-500 R/hr
RSO-50 Ranges
0-50 mR/hr
0-500 mR/hr
0-5 R/hr
0-50 R/hr
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Types of Radiation Detected/Measured
The Bicron RSO series of instruments are designed to measure gamma, X-ray and
beta radiation but will detect (not measure) fast neutron radiation. The
instruments will read
approximately 10%, in mR/hr, of the true neutron field, in mrem/hr. Like the
Eberline RO-2, the Bicron RSO series instruments will not respond to alpha
radiation because the alpha particles are shielded before they reach the detector.
The energy response of the two models is identical. Both models measure photon
radiation within +20% for photon energies from 12 keV to 7 MeV (beta shield
open). The minimum energy increases to 25 keV if the shield is closed, and to
about 40 keV through the side of the instrument. Both models measure beta
radiation >70 keV.
Operator-Adjustable Controls
RSO-500 range switch with OFF, ZERO, and BATT positions.
• Switch ranges labeled as 0.5, 5, 50, and 500 R/hr.
• ZERO position works in conjunction with ZERO knob to electronically
zero the meter.
• BAT position checks the two batteries used to power the instrument
circuitry and detector bias.
• OFF position turns the instrument off.
RSO-50 range switch is the same but is labeled 50 and 500 mR/hr and 5 and
50 R/hr.
Markings for Detector Effective Center
The effective center markings on both Bicron models are the stamped circles with
a plus sign in the circle and are located on the sides and front of the instrument
case. If the radiation field over the whole detector is not uniform ( such as from
surface contamination, radiation streaming, or from a small point source) the
displayed value may need to be corrected.
Specific Limitations/Characteristics
The response time varies between the two models of Bicron instruments available.
RSO-500 - approximately 10 sec from 0-90% of the final reading.
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RSO-50 - approximately 5 sec from 0-90% of the final reading.
Correction factors may be needed when the radiation field is not uniform over the
entire detector. High humidity or moisture can cause leakage currents in the
detector and cause erratic meter readings.
• The detector is vented through a desiccant, or drying medium, contained
in a plastic box.
• The desiccant can become saturated and will need replacement if the
crystals start to turn clear or pink.
Like the Eberline RO-2, the detector is vented to atmosphere; therefore, any
change in atmospheric density changes the air density in the detector.
• An increase in temperature will lower the air density in the detector and
cause a lower response.
• An increase in atmospheric pressure will cause an increase in air density in
the detector and cause a higher response.
• Tables are provided in the technical manuals for correcting the instrument
response due to changes in pressure or temperature
Section 142
• A change in response of about 10% will occur if the instrument was
calibrated at room temperature and used in an environment that is different
by about 50 ΕF.
Because the detector is vented to atmosphere, radioactive gases can enter the
detector and cause a reading.
VICTOREEN MODEL 450B
The Victoreen 450B is a portable, general purpose, ion chamber survey
instrument which uses microprocessor and LCD (liquid crystal display)
technology.
Detector Type
Operated as an ionization chamber. A Bakelite, or plastic, cylinder of 200 cm3
volume with one end open but covered by a Mylar window. The fill gas is air
(vented to atmosphere through a desiccant pack). The ion chamber detector is
designed as tissue-equivalent, allowing the instrument to accurately assess the
exposure rate to human tissue. The Victoreen 450B is operated in the current
mode as are most ion chambers.
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Instrument Operating Ranges
• Overall range is 0-50 R/hr.
The instrument is autoranging, or automatically changes scales as required for the
instrument reading, and has the following scales:
Detector Shielding
The active volume of the detector is shielded from the side by the detector wall
and the instrument case and from the bottom by the movable beta shield and
windows. The detector wall is 200 mg/cm2. The sliding beta shield is made of
Bakelite, which is a type of plastic and the density-thickness value is 440 mg/cm2.
Detector Window
The two detector windows, one on the detector and one on the case, are made of
1.7 mil Mylar for a total of 3.4 mg/cm2.
Type of Radiation Detected/Measured
The 450B instrument is designed to measure gamma, X-ray, beta and alpha
radiation but will detect (not measure) fast neutron radiation. The instruments
will read approximately 10%, in mR/hr, of the true neutron field, in mrem/hr.
Energy response. Photon energy response (+20%) is about 20 keV for slide open,
40 keV for slide closed, and 50 keV from the side. Beta energies >32 keV can be
measure. The alpha response is limited to energies >4 MeV and only if the
detector to source distance is less than the alpha range in air.
Operator-Adjustable Controls
Only three external controls are available on the 450B: the ON/OFF switch, the
MODE switch and the meter light button. The Mode switch is used during
calibration and is not enabled for operator use. The ON/OFF switch turns the
instrument on and off. The instrument is autoranging and will change the bar
graph, digital value and scale markings as appropriate for the exposure rate value.
450B Scales
0-5 mR/hr
0-50 mR/hr
0-500 mR/hr
0-5 R/hr
0-50 R/hr
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The instrument has an "autozero" feature that eliminates any need for an external
zero control. If the batteries are low, then the instrument will display a LOW
BAT message. A button switch is provided in the handle for turning the meter
face light on and off.
Markings for Detector Effective Center
The effective center markings on the 450B are the painted-white depressions in
the plastic case and are located in the front and on the sides.
Specific Limitations/Characteristics
The response times to 90% of the final value for the 450B instrument are as
follows, assuming that a step increase or decrease in the rate does not cause a
range change:
Section 143
450B Response Times
0-5 mR/hr
8 sec
0-50 mR/hr
5 sec
0-500 mR/hr
2 sec
0-5 R/hr
2 sec
0-50 R/hr
2 sec
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Geotropism, or the effect of gravity on the instrument, causes no greater than a +1% of
full scale change from the actual value. Correction factors must be applied when the
radiation field is not uniform over the entire detector, such as for surface contamination
beta dose rates. High humidity or moisture could cause leakage currents in the detector
and cause erratic meter readings. The detector is vented through a desiccant, or drying
medium, contained in a plastic cylinder. The desiccant could become saturated and will
need replacement if the crystals start to turn clear or pink. The atmospheric vent on the
case has a rubber bladder to allow for changes in temperature and pressure but prevents
the free flow of air into and out of the detector casing. The rubber bladder minimizes the
effects of high humidity environments and radioactive gases. The detector is vented to
atmosphere; therefore, any change in atmospheric density changes the air density in the
detector. An increase in temperature will lower the air density in the detector and cause a
lower response. An increase in atmospheric pressure will cause an increase in air density
in the detector and cause a higher response. The value of the changes due to temperature
and pressure are similar to those of other air-vented ion chambers.
EBERLINE TELETECTOR
The Eberline Teletector is an extendible, telescoping-rod instrument designed
with two Geiger-Mueller (GM) detectors for the measurement of photon exposure
rates and detection of beta radiation.
Detector Types
Both detectors are sealed GM tubes with halogen-quenched argon fill gas
contained in an energy compensating case. Energy compensation is required in
GM detectors to reduce the over response to low energy photons.
The low range detector is the largest of the two detectors and is located at the end
of the detector housing. The low range detector is used for the three lowest ranges
on the instrument.
The high range detector is the small cylinder in the detector housing, and is used
for the upper two scales.
2.16.03 Identify the following features and specifications for high range instruments
used at your facility:
a. Detector type
b. Instrument operating range
c. Detector shielding
d. Detector window
e. Types of radiation detected/measured
f. Operator-adjustable controls
g. Markings for detector effective center
h. Specific limitations/characteristics
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The GM detectors are very sensitive; however, they lack the direct correlation to
energy deposited and are not as accurate as ion chamber instruments for assessing
exposure rates.
The Teletector instrument is operated in the pulse mode, or the mode that counts
each individual pulse. Since any ionization in a GM tube causes the same large
pulse, any radiation interaction in the detector will be counted. All the pulses are
of the same large size regardless of the energy or type of radiation; therefore, all
information on the type and energy of the radiation is lost.
Instrument Operating Ranges
The instrument range is 0 - 1000 R/hr.
Section 144
The analog Teletector has five settings. The three lower settings utilize the large
GM detector and the two upper settings utilize the smaller GM detector.
Teletector Settings
0-2 mR/hr
0-50 mR/hr
0-2 R/hr
0-50 R/hr
0-1000 R/hr
Detector Shielding
The two detectors are shielded by layers of lead and fiber to compensate for the
GM over-response to low-energy photons. The high-range detector is partially
shielded by the low-range detector.
Detector Window
The low-range detector has a 30mg/cm2 mica window and a rubber cap to protect
the window.
Types of Radiation Detected/Measured
The Eberline Teletector will measure gamma and X-ray radiation and responds to
(but does not measure) beta radiation. According to the manufacturer, beta
response is not accurate. Alpha response is eliminated by the thicker window and
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casing. Neutron response is insignificant due to the lower probability of
interaction in the small detectors.
The Teletector measures photon radiation >80 keV. Lower energy photons are
attenuated in the detector window. Beta particles >160 keV can be detected but
not measured.
Operator-Adjustable Controls
The only control is the range switch with OFF and B (battery check) positions.
Detector Effective Center Markings
The effective center of both detectors is indicated by the machined grooves in the
detector housing, with the groove closest to the beta window indicating the low-
range detector.
Specific Characteristics and Limitations
Response time for the instrument is approximately 1 second to 90% of full scale.
The sealed detectors do not require correction factors for temperature or pressure.
The sealed detectors do not experience problems with humidity or radioactive
gases entering the detector.
Audible indication is available only through the speaker jack; no internal speaker
is installed.
For GM detectors, the possibility exists that the detectors become saturated in
very high radiation fields. Some GM detector instruments will read zero if the
detector becomes saturated. The manufacturer states (on the title page of the
6112B brochure) that the Eberline Teletector will not saturate, up to 30,000 R/hr
(which is larger than the maximum range).
It is easy to damage the instrument by bending the extendible tube.
EBERLINE RO-7
The RO-7 series instrument provides remote monitoring in high range beta and
gamma radiation fields. The RO-7 consists of a basic digital readout instrument,
three interchangeable detectors, and various interconnecting devices. The
detectors may be interconnected to the instrument by flexible cables of different
lengths, by rigid extensions of different lengths or by use of an underwater
housing.
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Detector Types
All three detectors are air-vented ion chambers contained in a plastic-lined
(phenolic) aluminum housing. The detector fill gas is air. The detector housing
also contains other electronics, such as an operational amplifier and detector
identification circuitry.
The three available detectors are as follows:
• The RO-7-LD is a low-range, gamma-only detector with an active volume
of about 50 cm3 and dimensions of 2.5 cm diameter and 10.2 cm long.
Section 145
• The RO-7-BM is a mid-range, beta/gamma detector, with beta window,
that has an active volume of about 7 cm3 and dimensions of 2.5 cm
diameter and 5 cm long.
• The RO-7-BH is a high-range, beta/gamma detector, with beta window,
that has an active volume of about 7 cm3 and dimensions of 2.5 cm
diameter and 5 cm long.
Each detector is labeled at the connector end of the detector.
• NOTE: Two small screws on the label are marked ZERO and CAL.
These should only be adjusted at calibration and must not be adjusted by
the operator.
The RO-7 instrument is operated in the current mode of operation.
Instrument Operating Ranges
The operating range of the instrument is dependent on the detector that is
connected to the instrument.
• The range of the RO-7-LD detector is 0-2 R/hr.
• The range of the RO-7-BM detector is 0-200 R/hr.
• The range of the RO-7-BH detector is 0-20 kR/hr (20,000 R/hr).
Detector Shielding
All three detectors have a phenolic liner and aluminum housing.
Detector Window
The RO-7-BM and RO-7-BH detectors each have a 7 mg/cm2 Mylar window.
The Lucite cap for the beta window is 100 mg/cm2.
Types of Radiation Detected/Measured
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As previously mentioned, the RO-7-LD detector measures only gamma and X-ray
radiation. Both beta and alpha radiation are shielded by the detector housing.
The neutron radiation response is insignificant due to the small size of the
detector. The actual detectors in the RO-7-BM and RO-7-BH detector assemblies
are identical. Both detect and measure gamma, X-ray and beta radiation. Alpha
response is eliminated by the 7 mg/cm2 window (same density thickness as the
outer layer of skin). Neutron radiation response is even smaller than the RO-7-
LD due to the smaller detector volume.
The energy response for the three detectors is as follows:
The RO-7-LD responds to photon radiation between 50 keV and 1.3 MeV
(+20%). The RO-7-BM and RO-7-BH detectors respond to photon radiation
differently depending on orientation and whether the Lucite cover is in place.
• Lucite cover off - 10 keV to 1.3 MeV (+20%)
• Lucite over on - 25 keV to 1.3 MeV (+20%)
• Shield on, from the side - 50 keV to 1.3 MeV (+20%)
• The beta response for the RO-7-BM and RO-7-BH detectors is for beta
energies >70 keV.
Operator-Adjustable Controls
The ON/OFF switch is the only range control because the instrument identifies
the detector model and adjusts the readout accordingly. A low battery condition
is indicated by a "colon" under the battery mark on the meter. The ZERO knob
will zero the LCD readout. A meter face light is turned on/off by the small switch
in front of the pistol grip.
Detector Effective Center
No markings are provided for the detector effective center.
Specific Limitations/Characteristics
The response time of the basic instrument is 2.5 seconds to 90% of the final
reading. The correction factor for the true beta measurement is 1.5 as
recommended by the manufacturer.
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Section 146
Since the detector is air-vented, atmospheric temperature and pressure changes
affect the instrument reading. The instrument response will remain within +10%
for the temperature range of -20 to 160 oF. A correction table is available in the
technical manual for pressure changes. The detectors are air-vented but do not
have a desiccant pack. The detector should be kept dry and out of high humidity
environments to prevent leakage currents. Each detector has associated
electronics designed for that particular range. Overranging a detector may cause
damage to the detector electronics. If the instrument is not calibrated with the
underwater housing and the housing is used, the response will be about 5% low.
The instrument reading should be multiplied by 1.05 to obtain the corrected
response.
Interconnecting devices from the detector to the instrument that are available from
the manufacturer are the:
• 15 ft flexible cable
• 60 ft flexible cable
• 2 ft rigid extension
• 5 ft rigid extension
• Stainless-steel underwater housing with 60 ft of cable.
NEUTRON DETECTORS
EBERLINE NRD NEUTRON SPHERE
The Eberline Neutron Rem Detector (NRD) sphere is a portable instrument for the
detection and measurement of the dose rate from neutron radiation.
Detector Types
The detector is the Eberline NRD (Neutron Rem Detector) sphere, which may be
connected to a PNR-4 (Portable Neutron Rem) or to an ESP (Eberline Smart
Portable) instrument by a coaxial cable. The NRD sphere is a 9 inch diameter,
cadmium loaded, polyethylene sphere with a BF3 proportional tube in the center
of the sphere. The BF3 (boron trifluoride) detector design allows the detection of
2.16.04 Identify the following features and specifications for neutron detection and
measurement instruments used at your facility:
a. Detector type
b. Instrument operating range
c. Types of radiation detected/measured
d. Energy response
e. Operator-adjustable controls
f. Specific limitations/characteristics
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neutrons only, and the rejection of other radiation. The thermal neutron capture
reaction with the 10B results in gas ionization pulses caused by the alpha particle
from the reaction:
1 10 2 4
0 5 3 2n+ B Li+ He⎯⎯→
or
( )10 2
5 3B n,α Li
The 9 inch diameter polyethylene sphere is used to moderate the neutrons. The
polyethylene has a high percentage of hydrogen which thermalizes the fast and
intermediate energy neutrons. Those neutrons that are thermalized in the sphere
can be detected in the BF3 tube. The cadmium loading is a thin sheet of cadmium
placed at a radius of about 7 cm inside the polyethylene sphere to help reduce the
over response to lower energy neutrons.
Instrument Operating Ranges
When the NRD is connected to the PNR-4 readout, there are two needles. One
needle covers the range up to 50 mrem/hr; above 50 mrem/hr, the second needle
takes over and covers the range up to 5000 mrem/hr. The NRD may also be
connected to an Eberline Smart Portable, ESP, which is discussed in lesson 2.17.
Types of Radiation Detected/Measured
Neutrons are measured. Alpha and beta radiation are not detected because they do
not penetrate the detector shielding. Gamma radiation passes through the detector
shielding but is rejected by the BF3 proportional chamber up to 500 R/hr
(dependent on high voltage setting and desired rejection level).
Section 147
Since the BF3 detector is operated in the proportional region, the pulses from the
alpha particles are larger than pulses from other interactions and trigger a pulse
height discriminator in the instrument circuitry. The mode of operation for the
instrument is the
pulse mode so that individual pulses can be discriminated and counted. Pulses
from gammas are rejected. Alpha and beta particles do not penetrate the
polyethylene sphere.
Energy Response
The energy response curve for the instrument shows the relative response of the
instrument as compared to the theoretical dose. This instrument over-responds to
intermediate energy neutrons, and under-responds to relativistic neutrons.
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Operator-Adjustable Controls
The only operator-adjustable control on the PNR4 is the OFF/ON/BAT switch
which turns the instrument on and off and allows a check of the battery.
No markings are provided for the detector effective center as the active volume of
the detector is centered in the sphere.
Specific Characteristics and Limitations
The response time depends on which decade of the scale is appropriate.
Response Times
First Decade 12 sec
Second Decade 6 sec
Third Decade 1.5 sec
Fourth Decade 0.3 sec
The detector is a sealed pressurized cylinder and is not affected by changes in humidity,
radioactive gases or changes in atmospheric density.
EBERLINE ASP-1 WITH NRD SPHERE
The Eberline ASP-1 with the NRD sphere is a microcomputer-based, analog-
display, portable neutron radiation survey instrument. The detector (Eberline
NRD sphere) is identical to the detector used with the PNR-4 readout packages.
The mode of operation is the pulse mode.
Instrument Operating Ranges
The overall range is 0-100 rem/hr and has a useable range of 1 mrem/hr -
60 rem/hr.
ASP-1 Ranges
0-1 mrem/hr
0-10 mrem/hr
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0-100 mrem/hr
0-1,000 mrem/hr
0-10,000 mrem/hr
0-100,000 mrem/hr
Detector shielding is the same as previously mentioned for the NRD sphere. The energy
response is the same as previously mentioned for the NRD sphere.
Operator-Adjustable Controls
The OFF/BAT/HV/range switch has the following functions:
• The OFF position turns the instrument off.
• The BAT position checks the instrument battery power supply.
• The HV position checks the applied high voltage to the detector and
should match the value listed on the special label on the instrument case.
The range markings are X1, X10, X100, X1K, X10K, and X100K with a meter
scale of 0-1.0.
The INTEGRATE/FAST/SLOW switch is a three position toggle switch with the
following functions:
• In the INTEGRATE position, the instrument will show the total dose
accumulated since the last time the instrument was reset to zero or turned
off.
• In the FAST position, the response time selected by the microcomputer is
for typical survey work.
• In the SLOW position, the response is slower but with greater accuracy
than the FAST position.
The LIGHT/RESET switch is a three-position, spring-loaded toggle switch with
the following functions:
• The LIGHT position illuminates the meter face
• The RESET position will zero the meter reading for the current
mode (INTEGRATE/FAST/SLOW) setting of the instrument.
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Module 2.16 Radiation Survey Instrumentation Study Guide
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The RESET switch will cause the "standard current" value to be displayed if held
for 5 seconds while in the FAST or SLOW mode. The SPEAKER is a two-
position toggle switch for turning the external speaker on and off. Acoustic
(airline-type) head phones can be plugged into the speaker cover on the top of the
instrument. As previously mentioned, the NRD sphere has no effective center
markings.
Specific Limitations/Characteristics
The response time of the instrument is controlled by the microcomputer and is
based on the input count rate and whether the mode switch is in FAST or SLOW.
In the FAST position, the instrument response time varies between one and ten
seconds. In the SLOW position, the instrument response time will vary up to a
maximum of 29 seconds. No correction factors are required to correct the
displayed value. The sealed detector is not affected by changes in atmospheric
density, humidity or radioactive gases. The instrument has a microcomputer
controlled "overrange" indication. When the radiation rate exceeds the useful
range of the detector, the computer will cause an overrange alarm. When the
instrument alarms, the meter needle will sweep back and forth and an interrupted
tone will sweep in the speaker.
SUMMARY
This lesson has covered the specifications, features and limitations for the
portable radiation survey instruments that may frequently be used by the RCT.
This knowledge should be used to properly select and operate the instruments to
ensure that the data obtained is accurate and appropriate. The appropriate and
accurate data is then used to properly assign external exposure controls.
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-1
Course Title: Radiological Control Technician
Module Title: Contamination Monitoring Instrumentation
Module Number: 2.17
Objectives:
2.17.01 List the factors which affects an RCT's selection of a portable
contamination monitoring instrument.
→ 2.17.02 Describe the following features and specifications for commonly
used count rate meter probes used at your site for beta/gamma
and/or alpha surveys:
a. Detector type
b. Detector shielding and window
c. Types of radiation detected/measured
d. Energy response for measured radiation
e. Specific limitations/characteristics.
→ 2.17.03 Describe the following features and specifications for commonly
used count rate instruments used at your site.
a. Types of detectors available for use
b. Operator-adjustable controls
c. Specific limitations/characteristics.
→ 2.17.04 Describe the following features and specifications for commonly
used personnel contamination monitors at your site.
a. Detector type
b. Detector shielding and housing
c. Types of radiation detected/measured
d. Scaler type uses
e. Scaler operator-adjustable controls
f. Specific procedures for source checks
g. Specific procedures for sample counts.
→ 2.17.05 Describe the following features and specifications for commonly
used contamination monitors used at your site (tool, bag, laundry
monitors).
a. Detector type
b. Detector shielding and window
c. Types of radiation detected/measured
d. Energy response for measured radiation
e. Specific limitations/characteristics.
Section 149
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-2
INTRODUCTION
This lesson covers contamination monitoring instruments in relation to types
used, purpose for, radiation monitored, operational requirements, and specific
limitations and characteristics. The RCT uses information from these monitoring
instruments to identify and assess the hazards presented by contamination and
establish protective requirements for work performed in contaminated areas.
References:
1. Radiation Detection and Measurement, Glenn F. Knoll.
2. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
3. Operational Health Physics, Harold J. Moe.
4. ANSI N323A.
5. (Various Manufacturers Technical Manuals.)
NOTE: Text is provided for some commonly used contamination monitoring
instruments (except those included by Objective 5). The site may adjust
text as necessary for instruments used at the site. Text added for specific
instruments used at the site must, at a minimum, cover the material
required by the objective.
GENERAL DISCUSSION
Measurements using portable contamination monitoring (count rate) instruments
provide the basis for assignment of practical contamination and internal exposure
controls. To establish the proper controls, the contamination measurements must
be an accurate representation of the actual conditions. Measurements using non-
portable contamination monitors, such as an Eberline PCM-1B or PM-6, are used
to identify personnel contamination prior to exiting controlled areas or facilities.
Measurements using counter scalers to determine the levels of transferrable
contamination on specific location samples are the basis for contamination
postings and material releases from controlled areas.
Many factors can affect how well the measurement reflects the actual conditions,
such as:
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2.17-3
• Selection of the appropriate instrument based on type and energy of
radiation, radiation intensity, and other factors
• Correct operation of the instrument based on the instrument operating
characteristics and limitations
• Calibration of the instrument to a known radiation field similar in type,
energy and intensity to the radiation field to be measured
• Other radiological and non-radiological factors that affect the instrument
response, such as radioactive gases, mixed radiation fields, humidity and
temperature.
FACTORS AFFECTING INSTRUMENT SELECTION
The selection of the proper instrument is critical to ensure the data obtained is
accurate and appropriate. Instrument selection is based on the characteristics and
specifications for that instrument as compared to the required measurements.
Several factors should be considered when selecting the instrument.
• The type of radiation to be measured
• The energy of the radiation to be measured
• The intensity of the radiation (dose rate or activity levels)
• Interference from a mixed radiation field
• Background radiation conditions
• Environmental factors, such as radioactive gases or temperature, affecting
instrument response
• Procedural requirements.
2.17.01 List the factors which affects an RCT's selection of a portable contamination
monitoring instrument.
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
Section 150
2.17-4
To ensure the proper selection and operation of instruments, the instrument
operator must understand the operating characteristics and limitations of each
instrument available for use.
COUNT RATE METER HAND PROBES
EBERLINE MODEL HP-210 AND VICTOREEN MODEL 110C
Models like the Eberline Model HP-210 or Victoreen Model 110C hand probes
are sensitive beta detectors using a thin window "pancake" Geiger-Mueller (GM)
detector. These detectors are designed for contamination surveys of personnel,
table tops, floors, equipment, etc.
Detector responds to alpha, beta, gamma and X-ray radiation of minimum
energies.
• alpha > 3 MeV
Detector must be close enough to the source of alpha particles to prevent
alpha particle attenuation in the air between the source and the detector.
• beta > 40 keV
This precludes the detection of low energy beta particles, such as the beta
particle from the decay of tritium (Emax = 18.6 keV).
• gamma > 6 keV
Photon radiation, such as gamma or X-ray, can interact in the detector
walls and the fill gas to create a pulse. However, the probability of
interaction is small due to the shallow depth of the detector and therefore
the efficiency for photon radiation is small.
GM tube has mica window of 1.4 to 2.0 mg/cm2 density
Gamma sensitivity is approximately 3,600 counts per minute (cpm) per mR/hr for
Cs-137.
2.17.02 Describe the following features and specifications for commonly used count
rate meter probes used at your site for beta/gamma and/or alpha surveys:
a. Detector type
b. Detector shielding and window
c. Types of radiation detected/measured
d. Energy response for measured radiation
e. Specific limitations/characteristics..
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2.17-5
Available with either high-density tungsten or aluminum housings
• HP-210AL - aluminum housing with a low shielding factor for low
background use
• HP-210T - tungsten shield covering the top and sides of the detector
allows use in high background area
• Victoreen 110C - aluminum housing with a low shielding factor for low
background use.
Victoreen 110C series hand probes are almost identical to the Eberline model HP-
210AL.
Detector Type
The detector is sealed Geiger-Mueller (GM) "pancake" detector. A "pancake"
detector has a radius or width that is much larger than the depth of the detector.
The shielded hand probe contains the GM detector which has the mica window
protected by a wire or stainless-steel etched screen. The fill gas in the GM tube is
halogen-quenched argon.
The operating voltage for the GM detector is 900V + 50V. The detector has a 50
μs resolving time which is defined as the minimum time that must elapse after the
measurement of an ionizing particle before a second particle can be measured.
Detector Window and Shielding
The thin detector window is 1.4-2.0 mg/cm2 mica and is protected by the screen
which is 79% open. Mica windows must be used instead of Mylar, because the
Mylar will react with the halogen quench gas. The window has an effective
surface area of 2.4 inch2 (15.5 cm2).
Efficiencies for the detector are dependent on the type and energy of the radiation.
The detector is designed, calibrated and used to measure beta radiation
22% for Cs-137
16% for Co-60
32% for Sr-90 -Y-90
15% for Tc-99
6% for C-14
Section 151
Typically, a conservative beta efficiency of 10% is assigned for these types of
problems. Therefore, to convert the cpm reading to a dpm value, the meter
reading is multiplied by ten (dpm = cpm x 10). Efficiencies for alpha and photon
radiation are not typically quoted because the probes are not calibrated for either
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-6
type of radiation. However, gamma efficiencies are low, about 1-2%, because of
the shallow detector depth. Alpha efficiencies are highly dependent on the
particle energy and distance from the source, but can be as high as 20%.
Specific Limitations and Characteristics
Generally, environmental conditions, such as humidity and temperature, do not
affect the response of the detector because it is sealed at a pressure slightly less
than atmospheric pressure.
Use of the hand probe at proper frisking speeds and distances is extremely
important to ensure accurate results. The probe should be used at a distance of no
more than 1/2 inch and at a speed of about 1 inch per second.
The mica window is extremely fragile and sufficient care must be taken to prevent
any punctures which will ruin the detector.
The detector probe is not calibrated for alpha radiation; however, it may be used
for indication of alpha emission from contamination, if used properly.
VICTOREEN MODEL 489-4 DETECTOR PROBE (THYAC)
The Model 489-4 detector probe is a cylindrical GM detector with a sliding beta
shield and can be used for high count rate applications of contamination
monitoring.
Detector Type
The detector is a sealed Geiger-Mueller (GM) cylindrical detector. The shielded
probe contains the cylindrical GM tube which has a stainless steel wall
surrounding the entire detector volume. The fill gas in the GM tube is halogen-
quenched argon. The operating voltage for the GM detector is 900V + 50V.
Detector Window and Shielding
The detector "window" is the 30 mg/cm2 stainless steel wall of the detector.
Shielding provided by a 360Ε sliding steel shield.
The GM detector will detect any radiation that interacts within the sensitive
volume of the detector.
Charged particle radiation must pass through the detector wall before an
interaction can take place; therefore, the minimum sensitivity for charged particle
radiation is based on the wall thickness and distance from the detector. The
minimum sensitivity for beta particles is about 200 keV with the shield retracted,
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-7
which precludes the measurement of most average-energy, fission-product beta
particles. The detector will not detect beta radiation with the shield in place.
Alpha particles can not be detected because all alpha particles would be stopped
in the detector wall.
Photon radiation, such as gamma or X-ray, can interact in the detector walls and
the fill gas to create a pulse. The minimum sensitivity for photon radiation is
about 6 keV with the shield retracted and about 70 keV with the shield in place.
Specific Limitations and Characteristics
Generally, environmental conditions, such as humidity and temperature, do not
affect the response of the detector because it is sealed at a pressure slightly less
than atmospheric pressure. When used with a count rate meter, the meter reading
(cpm) is converted to a dpm value by multiplying by thirty (dpm = cpm x 30).
The detector probe is not calibrated and is not recommended for measurement of
beta radiation due to the thickness of the detector wall.
Section 152
EBERLINE MODEL AC-3 ALPHA HAND PROBE
The Model AC-3 is an alpha scintillation detector used to identify alpha-emitting
contamination.
Detector Type
Scintillation detector using ZnS (Ag) powder embedded in tape. Active detector
area is 9.1 inch2 (59 cm2) within a 5 3/4 x 2 inch sampling area. Low gamma
sensitivity.
Detector Window and Shielding
Window is 1.5 mg/cm2 aluminized plastic film. Total probe assembly is 11 1/2
inches long x 2 3/4 inches wide x 3 1/4 inches. Clear plastic probe cover is
supplied for protecting the detector window. Weight of probe is 1 pound 6
ounces.
Efficiency
From a 1-inch diameter source or from 50 cm2 of a large-area distributed Pu-239
source, 2 pi geometry. Minimum efficiency is 28%. Typical efficiency is 31%.
Sensitivity to Pu-239 source is typically 2 x 107 cpm per microcurie/cm2.
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-8
Specific Limitations and Characteristics
Probe is sensitive to gamma radiation. Not used in areas where gamma
interference in mr/hr will indicate >300 cpm alpha. The mR/hr value is affixed to
each instrument during routine calibration.
Detector window is very fragile. Puncture or damage to covering will cause
detector to become sensitive to light.
Erratic meter movement can be due to electrical short in probe connection cable.
Detector is to be held 0.5 cm from the surface and moved at approximately 1-2
inches per second.
COUNT RATE INSTRUMENTS
VICTOREEN MODEL 496
Victoreen Model 496 is an analog GM count rate meter.
Used in conjunction with GM probe assembles to measure beta and gamma
radiation.
Victoreen 489-4
Victoreen 110-C
Eberline HP-210
Three operating ranges of 0-800, 0-8,000, and 0-80,000 cpm.
Response time of 10 seconds or less to 90% of the final reading.
Accuracy of +10% normally.
Weight of 4 pounds.
Operation
2.17.03 Describe the following features and specifications for commonly used count
rate instruments used at your site.
a. Types of detectors available for use
b. Operator-adjustable controls
c. Specific limitations/characteristics.
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-9
Meter face readout of 0-800
Rotary switch for power and range functions
• Off - setting for non-operation
• Batt - initial selection for testing of battery strength, needle will identify
battery strength
• x1 - establishes meter reading times 1 as the activity in cpm (0-800 range)
• x10 - identifies meter reading times 10 as the activity in cpm (0-8,000
range)
• x100 - identifies meter reading times 100 as the activity in cpm (0-
80,000 range).
Volume Control Rotary Switch
Audible indication of count rate by independently controlled speaker
Functions of off and on to control speaker
Correction factors for beta/gamma cpm to dpm reading based on type of detector
attached
Thyac 489-4 - meter reading x 30
Pancake probes - meter reading x 10
LUDLUM MODEL 12
Ludlum Model 12 is an analog count rate meter
Electronic circuitry has potential for use of proportional, scintillation, and GM
detectors
Available in three different detector configurations
Eberline HP-210 detector - used for beta-gamma measurement
Victoreen 110C - used for beta-gamma measurement
Eberline AC-3-7 Probe - used for alpha measurement
Operating ranges of 0-500, 0-50,000, and 0-500,000 cpm
Section 153
Fast-Slow toggle switch provides for meter response time selection
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-10
• Slow - response time of 22 seconds for 90% of final reading
• Fast - response time of 4 seconds for 90% of final reading.
Operation
Meter face readout of 0-500
Range multiplier selector switch is a six-position switch
1. OFF
2. BAT
3. x1,000
4. x100
5. x10
6. x1
Audio on-off switch for operation of count rate speaker
Fast-Slow toggle switch to establish response time of 4 seconds (fast) or 22
seconds (slow)
RES button provides a rapid means to reset the meter to zero
HV Test Button displays the detector voltage on the meter when depressed
Operates on two standard "D" cell batteries or rechargeable cells
Weight of 3.0 pounds, less detector and batteries
LUDLUM MODEL 3-6
Ludlum Model 3-6 is an analog survey instrument
Electronic circuitry has potential for use of proportional, scintillation, and GM
detectors
Operating ranges of 0-500, 0-5,000, 0-50,000, and 0-500,000 cpm
Fast-Slow toggle switch provides for meter response time selection
• Fast - response time of 5 seconds for 90% of the final reading
• Slow - response time of 25 seconds for 90% of the final reading.
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-11
Operation
Meter face readout of 0-5,000
Range multiplier selector switch is a six-position switch
1. OFF
2. BAT
3. x 100
4. x 10
5. x 1
6. x 0.1
Audio on-off switch for operation of count rate speaker
Fast-Slow toggle switch to establish response time of 5 seconds (fast) or 25
seconds (slow)
RES button provides a rapid means to reset the meter to zero
Operates on two standard "D" cell batteries or rechargeable cells
Weight of 3.5 pounds, less detector
LUDLUM MODEL 177-2
Ludlum Model 177-2 count rate meter is placed at specific locations for personnel
contamination monitoring
Electronic circuitry has potential for use of scintillation, and GM detectors
Available in conjunction with alpha, beta-gamma, and alpha-beta-gamma
detection probes
Operating ranges of 0-500, 0-5,000, 0-50,000, and 0-500,000 cpm
Fast-Slow toggle switch provides for meter response time selection
• Slow - response time of 22 seconds for 90% of final reading
• Fast - response time of 2.2 seconds for 90% of final reading.
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-12
Operation
Meter face readout of 0-500
Range multiplier selector switch is a six position switch
1. OFF
2. x 1
3. x 10
4. x 100
5. x 1,000
Audible click per radiation incident volume control adjustment
Operates on 115 V AC only and does not contain battery pack
RES Button provide a rapid means to reset the meter to zero
Alarm Set Selector Switch is 11 position switch used to select a predetermined
alarm threshold (0.5 to 500) at 100 cpm over background
Weight of 4.2 pounds, less detector.
PERSONNEL CONTAMINATION MONITORS
PERSONNEL CONTAMINATION MONITOR PCM-1B
Eberline Personnel Contamination Monitor, Model PCM-1B is a microprocessor-
based radiation detection system
Performs quick indication of beta-gamma contamination, with option of alpha
capabilities
PCM-1B has fifteen (15) independent gas-flow proportional detectors
Section 154
2.17.04 Describe the following features and specifications for commonly used
personnel contamination monitors at your site.
a. Detector type
b. Detector shielding and housing
c. Types of radiation detected/measured
d. Scaler type uses
e. Scaler operator-adjustable controls
f. Specific procedures for source checks
g. Specific procedures for sample counts.
DOE-HDBK-1122-2009
Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-13
Control processing unit (CPU) includes an Intel 8085 microprocessor, memory,
and input-output lines
Performs two-part personnel whole body survey by performing a right side then
lift, personnel body survey.
Operation mode
Monitor measure and stores background values for all detectors
Checks for high background alarm levels
Checks for low or high count failures
Checks for low gas pressure conditions
Ultrasonic motion sensor detects movement of person toward monitor
Background check is suspended
Display reads - "STEP UP - INSERT RIGHT ARM"
Placement of arm in arm cavity initiates personnel monitoring routine
Display reads - "COUNTING RIGHT SIDE"
Counting continues for duration of specific counting time
If no alarm levels detected, unit beeps and displays clearance
Display reads - "RIGHT SIDE OK -- INSERT LEFT ARM"
Placement of left arm in cavity initiates monitoring
Display reads - "COUNTING LEFT SIDE"
Counting continues for duration of specific counting time
If no alarm levels detected, unit beeps and displays clearance
Display reads - "COUNT COMPLETE, YOU MAY PASS"
Display accompanied by chime and the LED extinguishes.
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-14
Alarm modes
Premature arm withdrawal
Arm withdrawn prior to preset count time completion
Alarm alert sounds
Display reads - "COUNT INCOMPLETE **RECOUNT**"
Reinsertion of arm restarts count
Contamination detection
Activity in excess of alarm levels detected in either right or left side count
Alarm alert sounds at end of count time
Appropriate display appears - "ALARM: ZONE 1 - ZONE 2 - ZONE 3," etc.
Alarm and display continue for specified alarm hold time
Alarm stops and display reads - "CONTAMINATED -- PLEASE STEP OUT."
Troubleshooting
PCM-1B message display will illuminate the trouble or diagnostic lights to
identify various monitor malfunctions. Description of basic malfunction
conditions listed below:
High background - Background count rate in any zone(s) has increased above
selected limit.
Alarm light, high background light, sonalert, and "Channel Designation (i.e.,
'Zone 1 ft): High Background" message are activated.
Area should be checked for radioactive sources and/or detector checked for dirt,
moisture or radioactive contamination.
High count fail
• Alarm light, trouble light, sonalert, and channel designation message are
activated.
• Count capacity in any zone has been exceeded and PM Group to be
contacted for troubleshooting.
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-15
Low count fail or low sensitivity fail
• Alarm light, trouble light, sonalert, and channel designation message are
activated.
May be the result of component failure or decrease/loss of decrease/loss of
counting gas. Detector identified should be checked for leak in mylar. Leak in
mylar can be sealed with scotch tape.
Section 155
Contaminated detector
Contaminated detector light is activated along with contaminated detector
message. Operation will continue with detector light on.
Detector to be checked for contamination and decon around detector performed
with masslin cloth.
Loss of gas pressure
Two cylinders used but cylinder No. 1 used until empty. When empty, "Bottle
No. 1 Empty" light activated and No. 2 put in use automatically.
If both cylinders fail (empty) the trouble light, "Bottle No. 2 Empty," and display
with indicate "Failure**Out of Gas" message will be activated.
PCM-1B must not be used to monitor personnel with any trouble light
illuminated. Monitor placed in "Out of Service" mode until cause corrected.
EBERLINE PM-6
Microprocessor based radiation monitor using gas-flow proportional detectors for
whole body contamination scans.
Two basic types of PM-6s are typically used.
PM-6A
Uses eleven gas-flow counters to detect beta-gamma contamination.
Same basic operating characteristics as PCM-1B.
Source checked daily using beta-gamma source.
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Module 2.17 Contamination Monitoring Instrumentation Study Guide
2.17-16
PM-6A-2
Uses fifteen gas-flow counters to detect alpha or beta-gamma contamination.
Four additional detectors used in hand pods to increase ability to detect hand
contamination.
Hand and foot detectors sensitive to alpha as well as beta-gamma contamination.
Source checked daily using alpha and beta-gamma sources for both hand and foot
detectors. Beta-gamma source is used on body detectors.
Source checks and troubleshooting PM-6 is same as PCM-1B.
OTHER CONTAMINATION MONITORS
(Site must add material based on other contamination monitors, such as tool, bag
or laundry monitors, used at the site. Text added must cover the material required
by the objective.)
SUMMARY
In this lesson, we have covered contamination monitoring instruments in relation
to types used, purpose for, radiation monitored, operational requirements, and
specific limitations/characteristics for use. The RCT uses this information to
identify and assess the hazards presented by contamination and establish
protective requirements for work performed in contaminated areas.
2.17.05 Describe the following features and specifications for commonly used
contamination monitors used at your site (tool, bag, laundry monitors).
a. Detector type
b. Detector shielding and window
c. Types of radiation detected/measured
d. Energy response for measured radiation
e. Specific limitations/characteristics.
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-1
Course Title: Radiological Control Technician
Module Title: Air Sampling Equipment
Module Number: 2.18
Objectives:
2.18.01 Identify the factors that affect the operator's selection of a portable
air sampler.
→ 2.18.02 Identify the physical and operating characteristics and the
limitation(s) of the Staplex and Radeco portable air samplers.
→ 2.18.03 Identify the physical and operating characteristics and the
limitation(s) of Motor air pumps.
→ 2.18.04 List the steps for a preoperational checkout of a portable air
sampler.
→ 2.18.05 Identify the physical and operational characteristics and the
limitation(s) of beta-gamma constant air monitors (CAMs).
→ 2.18.06 Identify the physical and operating characteristics and the
limitation(s) of alpha constant air monitors (CAMs).
Section 156
INTRODUCTION
This lesson covers air sampling equipment in relation to types used, operational
and physical characteristics, limitations, and methods of sampling. The RCT uses
this information to identify and assess the hazards presented by airborne
contamination and establish protective requirements for work performed in
airborne contamination areas.
References:
1. "Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
2. Operational Health Physics, Harold J. Moe.
3. ANSI N323A.
4. (Various Manufacturer Technical Manuals.)
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-2
NOTE: The text is provided for some commonly used instruments. The site must
adjust text as necessary for instruments used at each site. Text added for
specific instruments used at the site must, at a minimum, cover material
required by the objectives.
SELECTION FACTORS
The factors affecting the selection of portable air samplers are:
• Type of radiation emitted by airborne contaminant in question
• Physical state of airborne contaminant
• Type and duration of job being performed.
PHYSICAL AND OPERATING CHARACTERISTICS AND LIMITATIONS
STAPLEX
Operational characteristics
• Centrifugal force is the method used to induce air movement. Centrifugal
force produces kinetic energy. Resultant velocity pressure converted to
suction for moving sampled air
• Self-cooling - Inappropriate for long-term continuous sampling
• Variable orifice flowmeter calibrated 0-70 cfm. Flow rate sticker on side
is specific for appropriate collection method. Typical flow rate(s): 7-
28 cfm
Physical characteristics
• 110-V fan motor with on-off switch. Requires external power source
• 4-inch filter holder assembly with intake screen. MSA charcoal adaptor
available
• Portable: 10 pounds
2.18.01 Identify the factors that affect the operator's selection of a portable air
sampler.
2.18.02 Identify the physical and operating characteristics and the limitation(s) of the
Staplex and Radeco portable air samplers.
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-3
Limitations
• Inappropriate for long-term continuous sampling
• May create an airborne area due to exhaust
• potential "crawler" while in operation due to the high torque generated by
the fan
• DO NOT use in explosive atmospheres
Methods of sampling
• Filtration
• Adsorption, if charcoal is used
• Impaction, if impactor head is installed
Placement for surveys
• Avoid creating airborne activity through stirring up dust with sampler
exhaust air
• Tripods available
• May be hung on chain for optimum positioning
Annular Kinetic Impactor Head
• Inertial Collector-Head collects large airborne particles such as plutonium
without collecting coexisting particles containing radon and thoron
• Principle: Air to be sampled enters annular space at rear, makes a 180-
degree turn at greased planchet, and out the center tube
• Size of particles collected can be varied by adjusting slit width and air
flow velocity
• Physical characteristics. - Head replaces Staplex screened intake orifice.
Lightly greased planchet placed on head intake.
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-4
RADECO (H809-VI)
Section 157
Operational characteristics
• Equipped with rotameter air flow indicator. Rotameter consists of a
"float" which is free to move up and down and a vertical tapered tube,
which is larger at top than bottom and contains the float. Air flows up the
tube causing float to rise. Height to which float rises is proportional to air
flow rate
• Many different types of floats found at facilities however, rotameters are
conventionally read at the highest point of maximum diameter, unless
otherwise indicated. If in doubt about how to read a particular rotameter,
check with supervision.
• Flow rate adjustable from 1 to 8 cfm
• 110-125 VAC
Physical characteristics
• Equipped with a two-stage turbine blower and one horsepower self-
cooling universal type motor
• Sample head uses 2 in. or 47 mm particulate and iodine filters
• Instrument panel has a three-position switch - (HIGH/OFF/VARIABLE),
a control knob for FLOW ADJUST, a fuse holder, and a rotameter
• Weight: 10 lbs
Limitations
• Cannot be used in explosive atmospheres
• Inappropriate for long-term continuous sampling
Methods of sampling employed
• Filtration
• Adsorption, if charcoal is used
2.18.03 Identify the physical and operating characteristics and the limitation(s) of
Motor air pumps.
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-5
MOTOR AIR PUMPS
Types of motor air pumps:
• MotoAir
• ITT
• Eberline.
These units normally used to sample for extended periods of time at low flow
rates.
Operational characteristics of typical motor air pumps
• Flow rate maintained relatively constant by regulator.
• Requires 110 V power supply.
Physical characteristics of typical motor air pumps
• Sample heads used designed to accept 2 inch diameter (47 mm) media for
both particulates and iodine.
• Common components are the carbon vane pump, the constant flow air
regulator, and the flow meter.
• Grounded three wire power cord is provided.
Typical features - Eberline RAS-1
• Operational characteristics - Rotameter type flow meter with a flow rate
range 0.5 to 3.5 cfm and power requirement 5 amps
• Physical characteristics - 'Screw in' type particulate filter holder, a
'Clamshell' type iodine filter holder, a ON/OFF power switch, and weight
is 30 lb
Sampling considerations
• Filter paper must cover intake screen.
• Charcoal cartridge holder must have good seal.
• Check flow rate after turning on and before turning off.
DOE-HDBK-1122-2009
Module 2.18 Air Sampling Equipment Study Guide
2.18-6
Reading a rotameter
• Rotameter consists of a "float" which is free to move up and down, and a
vertical tapered tube, which is larger at top than bottom and contains the
float.
• It operates using air pressure. Air flows up the tube, causing the float to
rise. Height to which float rises is proportional to air flow rate.
• Rotameters are conventionally read at the highest point of maximum
diameter, unless otherwise indicated.
PREOPERATIONAL CHECKOUT OF PORTABLE AIR SAMPLERS
1. Verify the air sampler has a current Calibration Sticker.
2. Physical Damage
• Power cord in good condition
• All gaskets in place
• General physical condition of housing and controls.
3. Working Condition
• Verify operating properly by checking for sound (no unusual
noises), sight (no smoke, no excessive sparking from motor
brushes), smell (no burning), and feel (no unusual vibration, not
overly hot to touch).
Section 158
• Appropriate air flow
• Controls on sampler are operable
• Ensure filters and cartridges are loaded in proper orientation to air
flow prior to sampling.
2.18.04 List the steps for a preoperational checkout of a portable air sampler.
2.18.05 Identify the physical and operational characteristics and the limitation(s) of
beta-gamma constant air monitors (CAMs).
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2.18-7
BETA-GAMMA CONSTANT AIR MONITORS (CAMs)
General Characteristics
• Continuously monitor quality of particulate beta-gamma airborne activity
in selected area.
Physical characteristics
• GM detector(s) - usually pancake type. Some utilize one GM detector to
measure activity on filter. Others utilize two GM detectors; one GM
detector used to measure activity on filter, and the other GM detector to
measures ambient background for background subtraction.
• Filter paper holder assembly in lead shield
• Strip chart recorder
• Mounted on enclosed, portable cart
• Photohelic air flow meter
• Alarm lights for high Activity alarm and low air flow alarm.
Limitations of CAMs
• Low air flow - must be placed near or downwind suspected source
• Poor response to low energy beta
• Lead shield ineffective for high gamma energies, therefore the CAM must
be in low background
• Responds to radon, thoron, and daughters which can produce a fluctuating
background on recorder.
• Not very portable; approximate weight 500 pounds
Method of sampling
• filtration
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Operation and Use
• Initial startup - Check all switches in off position (Master switch and HV
switch) plug in power cord (110 V) - Air blower will start and reset any
alarms that activate
• Ensure sufficient filter paper
• Turn master switch on and allow two minute warmup
• Turn HV switch on and allow 30 second warmup
• E & I to adjust the following settings: HV level, high and low level alarm
settings scale switch overlap setting
• Set recorder speed selector switch; 3/4 in. per minute to ascertain chart
moves, 3/4 in. per hour, routine operation
• CAM operating if slow buildup noted on recorder chart.
ALPHA CONSTANT AIR MONITORS (CAMs)
Continuously monitor quality of particulate alpha airborne activity in selected
areas
• Operating characteristics - Air pumping system pulls air through impactor
head. Count rate meter monitors planchet which will activate high activity
alarm horn and light at preset points.
Physical characteristics
• External cabinet features are: power supply, magnehelic gauge, count rate
meter (CRM), recorder chart, power switches, outlets, photohelic air flow
meter, and alarm lights (Radiation alarm and Low flow alarm).
• Internal cabinet features are: Annular Kinetic Impactor sample head,
blower, planchet (greased with ZnS and Silicone) and the Photomultiplier
(PM) tube.
2.18.06 Identify the physical and operating characteristics and the limitation(s) of
alpha constant air monitors (CAMs).
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Limitation(s)
• Does not give extremely accurate quantitative alpha measurement, but it
gives warning of increase activity and is possible to make estimates.
Section 159
• Dust buildup and radon-thoron activity affect efficiency.
Method of sampling
• Impaction
Operation and Use
• Initial startup.
• Place new "Alpha Tak" planchet on impactor head: Open light tight box
door, move PM tube housing from impactor head, remove any used
planchet, place new planchet on impactor head, move PM tube housing
back into position, close door, indicate action on recorder chart (date,
time, etc.), and take any used planchets to HP office for processing.
• Plug in power cord ensuring all switches are off prior to plugging power
cord in.
• Turn on switches in following order: outlet switch, then CRM power
switch.
• Set CRM to x 1 scale.
• Set alarm to desired level.
• Set CRM PHA/GROSS switch to GROSS.
• Notify E & I and/or supervisor of any malfunctions.
SUMMARY
This lesson covered air sampling equipment in relation to types used, operational
and physical characteristics, limitations, and methods of sampling. The RCT uses
this information to identify and assess the hazards presented by airborne
contamination and establish protective requirements for work performed in
airborne contamination areas.
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Module 2.19 Counting Room Equipment Study Guide
2.19-1
Course Title: Radiological Control Technician
Module Title: Counting Room Equipment
Module Number: 2.19
Objectives:
→ 2.19.01 Describe the features and specifications for commonly used
laboratory counters or scalers:
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation detected and measured
e. Operator-adjustable controls
f. Source check
g. Procedure for sample counting
→ 2.19.02 Describe the features and specifications for low-background
automatic counting systems:
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation detected and measured
e. Operator-adjustable controls
f. Source check
g. Procedure for sample counting
→ 2.19.03 Describe the following features and specifications for commonly
used gamma spectroscopy systems.
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation measured
e. Procedures
INTRODUCTION
An overview of counters, scalers and associated equipment will describe the basic
functions of counting equipment used to detect radiation activity. The RCT uses
information from these counting instruments to identify and assess the hazards
presented by contamination and airborne radioactivity and establish protective
requirements for work performed in radiological areas. Stand-alone counters or
scalers measure gross activity while spectroscopy systems perform spectrum
analysis to identify and quantify activity from specific nuclides. The common
uses of counting room equipment in various facilities will be discussed.
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A variety of counting equipment is used. There are both manual and automated
counting systems. There is shielded equipment to measure radioactivity just
above background
levels. There is equipment to measure gross counts of alpha, beta and gamma to
determine if surface contamination limits are met. There is equipment to measure
the energy spectrum for alpha and gamma radiation so that individual isotopes can
be identified and quantified (e.g. to determine if an alpha emitter is a plutonium
isotope, a uranium isotope or a radon daughter).
Section 160
The counting systems use various types of detectors, including gas proportional
counters for alpha and beta radiation; sodium iodide, scintillation detectors for
gamma spectroscopy; zinc sulfide (ZnS) scintillation detectors for alpha radiation;
liquid scintillation for tritium and carbon 14; surface barrier (semiconductor)
detectors for alpha spectroscopy, lithium drifted germanium (GeLi
semiconductor) detectors for gamma spectroscopy, and high purity, germanium
(HPGe semiconductor) detectors for gamma spectroscopy.
The most common uses of the equipment are to count smears, swipes and air
filters. Nose swipes are also counted as one way to test if an individual has been
exposed to airborne radioactive contamination. Both workplace and stack
emission air filters are counted to measure the concentration of specific
radionuclides (e.g. plutonium, and uranium) and classes of radionuclides (e.g.
mixed fission products).
References:
1. “Radiation Detection and Measurement,” Glenn F. Knoll, 1979.
2. “Basic Radiation Protection Technology"; Gollnick, Daniel; 5th ed.;
Pacific Radiation Corporation; 2008.
3. “Operational Health Physics,” Harold J. Moe, 1988.
4. ANSI N323A.
5. Various Manufacturer Technical Manuals.
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2.19-3
GENERAL PRINCIPLES
A variety of counting room systems are used. The principles of these systems will
be discussed in general and then specific systems will be described.
Detector Type
When looking for low levels of radioactivity from alpha emitters (e.g. U, Pu, etc.)
it is important to minimize the background count rate from betas and gammas.
The principle used to accomplish this is pulse height discrimination. Betas have a
range that is about 100 times greater than alphas, so alphas will deposit about 100
times as much energy in a thin detector, producing a larger pulse than betas.
Therefore alpha detectors are thin (typically 1 mg/cm2) and use pulse height
discrimination to distinguish alphas from betas.
Alpha detectors are generally either gas proportional counters, ZnS scintillators,
or silicon semiconductors.
Gamma spectroscopy requires good resolution to distinguish the different energy
peaks. GeLi or HPGe semiconductors give the best resolution, though NaI
scintillators are also used.
Detector Shielding
To reduce the background, shielding is often used. Betas can be shielded with
aluminum or plastic, while typical gamma shielding is a few inches of lead.
Detector Window
Since alphas have a short range the windows are thin, typically 1 mg/cm2 (or 0.25
mil plastic). Some detectors have no window between the sample and the
detector; in this case there is a gas purge system for gas proportional counters, or
a light tight housing for scintillators. The alpha range is so short that self-
shielding is often significant, e.g. an alpha emitter buried in a filter may be
shielded from the detector by the fibers.
Types of radiation
Some of the detectors discussed in objectives 1 and 2 are designed for alphas,
some for betas, and some will count both. Gamma spectroscopy is discussed in
Objective 2.19.03. Most nuclides emit more than one type of radiation, but
beware of exceptions (like Be-7 or C-14).
Beta background is greater than alpha, so alpha detectors use pulse-height
discrimination to differentiate between alphas and betas.
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Section 161
Module 2.19 Counting Room Equipment Study Guide
2.19-4
Some gammas will generally be detected in these detectors, but thin detectors
have low gamma efficiency, and lead shielding helps to reduce the gamma
background still further.
Operator adjustable controls
Counting room systems have a timer to allow the operator to measure the number
of counts per minute (cpm). The most common count time is 1 minute, but the
count time can be selected by the operator.
Sources
National Institute of Standards and Technology (NIST) standard sources are used
to check the systems. Common sources are Pu-239 for alpha and Sr-90 for beta.
Procedures
Procedures generally include:
• background count
• source check
• sample count
• background subtraction
• divide by time to get cpm
• correct for 4 pi efficiency to get dpm
• record the data
LABORATORY COUNTERS OR SCALERS
In this section, specific laboratory counters or scaler systems are discussed,
illustrating the general principles discussed above.
Sample Holder SH-4 with HP210 and ESP
The simplest system for counting smears is the portable contamination survey
instrument, the Eberline smart portable ESP with hand probe HP210.
2.19.01 Describe the features and specifications for commonly used laboratory
counters or scalers:
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation detected and measured
e. Operator-adjustable controls
f. Source check
g. Procedure for sample counting
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2.19-5
Recall from lesson 2.17 that the HP-210 probe is a pancake GM detector with a
thin (1.4 to 2 mg/cm2) window, suitable for detecting contamination from beta
emitting nuclides, and alphas above 3 MeV. The HP210T is shielded with
tungsten to reduce gamma background. The HP210AL is shielded with aluminum
to reduce beta background.
The problem with using the HP210 for quantitative measurements (e.g. to satisfy
release criteria) is one of ensuring a precise geometry. The SH-4 sample holder
solves this problem by holding the sample in a fixed position directly under the
HP210 detector.
Eberline Scintillation Alpha Counter SAC-4
The Eberline SAC-4 is a scintillation alpha counter. The scintillation phosphor is
ZnS powder on a plastic light pipe. The system is a self contained unit with the
detector and associated electronics housed in a single unshielded box. The
detector and sample are both in a light tight can, so no window is required
between the ZnS detector and the sample.
The system will accept samples up to 2 inches in diameter by 3/8 inches thick.
(Self shielding would be a major problem with samples this thick.) The sample
holder in the slide drawer is adjustable. It can be moved closer to the detector for
thin samples. However, the SAC-4 is calibrated with the sample holder in a
certain position, so if the sample holder is moved, the calibration is no longer
valid.
The electronic package consists of the high voltage power supply used to power
the photomultiplier tube and determine its amplification, and a linear amplifier.
The linear amplifier output provides a 0 to 10 volt pulse signal to the
discriminator that is set to 1.25V above the base line. Only pulses with
amplitudes above 1.25V will be counted. This will discriminate against betas
because they will produce smaller pulses.
Section 162
The output from the discriminator is counted by a six decade light emitting diode
(LED) readout. The timing circuit is synchronized to the line frequency (60 Hz)
and provides preset counting times from 0.1 to 50 minutes controlled by front
panel switches. This scaler can also be operated in a manual mode which will
continue to count until reset by the operator.
A Pu-239 source is used to check the system prior to each operating shift.
Background counts are conducted as a part of the performance check and to check
for detector contamination. The detector and sample drawer are easily removed
for decontamination if required.
The gross count rate is obtained by dividing total counts by the time in minutes.
Background counts (typically 0.3 cpm) are subtracted from gross counts to obtain
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2.19-6
net counts per minute (cpm). The net count rate (cpm) is corrected for efficiency
(as described in lesson 2.03) to convert cpm to disintegrations per minute (dpm).
This counting system is used to obtain total activity and the procedures are
followed as described in the SAC-4 manual. Each background, source count, and
sample count is documented and kept on file.
NMC PC-5 and PC-55 Nuclear Measurement Corporation
The PC-5 and PC-55 systems use gas flow proportional counters as the detectors.
The gas used in these detectors is P-10 (90% argon and 10% methane). The
systems are self-contained units with the detector and associated electronics
housed in the same box. The PC-55 is used to count both alpha and beta. The PC-
5 may be manually adjusted to count
either alpha or beta. It is normally set to count alpha only. The determination of
an alpha count or a beta count is accomplished by pulse height discrimination.
No external shielding is used. Typical background for the unshielded detector is 2
cpm for alphas, and 60 to 100 cpm for betas.
The PC-5 and PC-55 have identical detectors, 2.25 inch in diameter. They may
be installed with thin plastic windows with a thickness of 0.25 mil (0.00025 inch,
1 mg/cm2) or they may be installed with no window. If there is no window, the
operator must purge with P-10 gas after inserting a sample and closing the gas
tight door.
Front panel controls allow for pre-set gas purge times of 12, 36 and 144 seconds.
If the detector is installed with a thin plastic window, the normal procedure is to
flow the gas continually.
The sample to be counted is placed in a 2 inch diameter planchet and placed in the
sample drawer. The sample drawer then slides the sample under the detector.
Should the detector drawer or sample holder become contaminated during
counting, it is a simple task to remove the detector and drawer for
decontamination.
The high voltage supply has a dual operating range of 300 - 1300 volts and 1300 -
2300 volts controlled from a front panel voltage potentiometer. The high voltage
determines the optimum setting to discriminate alphas from betas.
The count time is also set by front panel switches providing pre-set counting
times in 0.1 minute increments up to 1000 minutes. In the automatic mode, the
counter will count to the pre-set time interval. In the manual mode, the counter
will continue to count until manually reset.
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2.19-7
Section 163
Two sources are used to check the system for proper operation. The alpha source
is Pu-239 electroplated on a nickel disc. The beta source is 90Sr/90Y (Strontium-
90 and its daughter, Yttrium-90). These sources are traceable to NIST (National
Institute of Standards and Technology).
LOW-BACKGROUND AUTOMATIC SYSTEMS
In this section, several automatic counting systems are discussed. The principles
are the same as in Objective 2.19.01. The essential differences between the
systems in Objectives 2.19.01 and 2.19.02 are:
• complexity of electronics
• number of detectors or automated sample changing
• shielding to reduce background
Canberra 2400
The Canberra 2400 is a low background automatic counting system. The primary
detector is a gas flow proportional counter with a 2.25 inch diameter thin window,
used to count both alpha and beta activity. A second larger proportional counter,
the guard detector, is
used to count background. The gas used is P-10 (90% argon and 10% methane).
The system may also incorporate a NaI scintillation detector, an option with the
Canberra 2400 systems, to simultaneously count gamma rays.
The sample detectors are surrounded by 4 inches of lead shielding to reduce
background. Typical background is 0.1 to 1 cpm alpha, 1 to 5 cpm beta, and 100
to 400 cpm gamma.
Canberra 2400 systems are used primarily to count smears or filters. Gross counts
for each sample are processed in the computer and converted to dpm. Smear
counts above preset limits are highlighted and printed on a separate report.
Performance checks are performed daily or prior to system use. NIST traceable
sources of Pu-239 (plutonium), Sr-90 (strontium), and Tc-99 (technetium) are
used. The system should be calibrated regularly, or when chi-square values are
outside the specified range (see lesson 2.03 for a discussion of the chi-square
test).
2.19.02 Describe the features and specifications for low-background automatic
counting systems:
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation detected and measured
e. Operator-adjustable controls
f. Source check
g. Procedure for sample counting
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2.19-8
The system has an automatic sample changer with a dual stack that can handle up
to 100 samples. One stack holds the samples to be counted and the other stack
stores the samples that have been counted.
Berthold LB770
The Berthold LB770 counting system is a low background semi-automatic
counting system. The system uses eleven P-10 gas flow proportional detectors;
ten detectors are used to count 10 radioactive samples simultaneously, the other
detector is used to count background radiation.
Each detector has a 2.25 inch diameter by 0.25 mil (0.00025 inch) mylar window.
The detector bay is shielded with 4 inches of epoxy coated lead. Typical
backgrounds are 0.1 cpm alpha and 1 or 2 cpm beta. Typical counting
efficiencies are 27% alpha and 42% beta. The planchet is 0.25 inch deep, but a
0.25 inch thick sample would cause major self-shielding problems (see lesson
2.03.01).
The Berthold systems are used primarily to count smears. Both alphas and betas
are counted simultaneously in each detector. Determination of alpha or beta
activity is accomplished by both pulse amplitude and pulse shape discrimination.
The scalers in the Berthold systems are similar to those used in the PC-55 but
with more sophisticated electronics that provide improved pulse shaping from the
linear amplifier and better discrimination of both pulse amplitude and pulse shape.
Section 164
Pu 239 sources are used to check the system for alpha and 90Sr/90Y sources are
used to check for beta. These sources are traceable to NIST (National Institute for
Standards and Technology).
The Berthold system is controlled by a computer. Both alpha and beta counts
received from each sample are corrected for background and reported in one of
three categories, to alert the operator. If the count rate is below the minimum
detectable activity (MDA, see lesson 2.03) it falls into category 1. A count rate
that falls within predetermined limits, usually above MDA but below the limit for
release to a controlled area (RadCon table 2.2) is category 2. And a count rate
that is higher than the upper limit is category 3.
Background and efficiency data are collected for each detector, stored and used
for corrections. Pre-set count times are determined by the operator and put into
the computer. The count rate data from each detector is corrected and converted
to dpm for output to the printer.
Liquid Scintillation Counters, LSC e.g. Packard 2550
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Module 2.19 Counting Room Equipment Study Guide
2.19-9
Tritium and C-14 emit such low energy betas that even a thin layer of air would
stop the betas. To detect this radiation, the sample must be in intimate contact
with the detection medium. This is achieved with a liquid scintillation system.
A liquid scintillation counting system uses a "cocktail" that immerses the sample
in the counting medium to maximize the detection efficiency for low energy beta
emitters. This cocktail includes a liquid scintillator to convert the energy
deposited by low energy betas into light photons, which are then counted using
photomultipliers.
The sample chamber, containing the sample vial and photomultiplier tubes, is
light tight. Since stray electrons can be spontaneously emitted from the
photocathode, or by the dynodes in the photomultiplier tube, two tubes are used
with coincidence circuitry to reduce this source of noise called "dark current".
Typical background for beta is 20 cpm.
The LSC system is typically used to count tritium samples from swipes, water
samples, and oil samples (vacuum pumps). Tritium is also collected by drawing
air samples through silica-gel traps or glycol bubblers.
To calibrate the system, a series of cocktails with known amounts of tritium are
prepared. These sources are loaded into the first sample holder (a tray of 10
sample vials). The computer program calculates the detector efficiency for each
calibration source.
GAMMA SPECTROSCOPY
The instruments discussed in objectives 1 and 2 are designed to detect alphas
and/or betas, and make a gross count of total alpha and beta activity. In order to
identify specific radionuclides, the unique spectrum of energies particular to each
radionuclide is used. This technique is known as spectroscopy.
Alpha emitters (e.g. Th, U, Pu, Am and their daughters) have characteristic alpha
energies, but alpha spectroscopy, detecting the alphas directly, is not optimal,
because the energy loss of alpha particles between the sample and the detector
smears the energy spectrum (see lesson 2.18.03). Gamma spectroscopy looks for
the characteristic spectrum of gammas from the radioactive decay.
2.19.03 Describe the following features and specifications for commonly used gamma
spectroscopy systems.
a. Detector type
b. Detector shielding
c. Detector window
d. Types of radiation measured
Section 165
e. Procedures
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2.19-10
Gamma spectroscopy usually uses germanium detectors (GeLi or HPGe) because
the good resolution obtained with these detectors enables gammas with nearly the
same energy to be distinguished or resolved.
EG&G Ortec Gamma X
The Gamma X Spectroscopy system uses an HPGe coaxial photon detector to
perform gamma and x-ray spectroscopy in the energy range from 3 keV to 10
MeV.
Detector Type
The detector is made of n-type high purity germanium semiconductor (HPGe). A
30 liter dewar of liquid nitrogen (LN2) is used to cool the detector.
Detector Shielding
The detector is shielded by 4 inches of pre World War II steel. This steel is used
when a low background is desired as it was manufactured before radioactive
fallout (artificial radioactivity, lesson 1.06.03) from nuclear weapons appeared in
trace quantities. A sample holder inside the shield allows the sample to be
positioned at distances from less than 1 cm up to 40 cm from the detector end cap.
Detector Window
The detector window is 0.5 mm thick beryllium.
Types of Radiation Measured
The gamma spectrometer is designed to detect gammas and x-rays from alpha
emitting nuclides, and sort the data in a multi channel analyzer to produce a
spectrum that is characteristic of the nuclide. The peaks in the spectrum are close
together, so excellent resolution is required to distinguish the peaks. Typical
resolution from a germanium semiconductor detector (HPGe or GeLi) is better
than 1%, which means that if the photon energy is 100 keV, the width of the peak
is less than 1 keV. Photons from two different nuclides that are 1 keV apart will
be seen as two distinct peaks.
Procedures
Energy and efficiency calibrations are obtained using two different sources that
are NIST standards. These are mixed sources that contain several gamma
emitting nuclides. One source contains isotopes of americium (Am), antimony
(Sb), and Europium (Eu). The second mixed source contains isotopes of
cadmium (Cd), cerium (Ce), cobalt (Co), strontium (Sr), tin (Sn), cesium (Cs),
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Module 2.19 Counting Room Equipment Study Guide
2.19-11
and yttrium (Y). The energy and efficiency calibration values are then used by
the analysis software.
Specific procedures are written to direct the operator through the sample and
computer setup, and the computer analysis. The original copy of the results is
kept on file for 1 year and then archived for 75 years.
SUMMARY
This lesson has discussed the detector, shielding, window, types of radiation
detected, and procedures for counting room equipment. This knowledge is
important to ensure accurate and consistent counting room data for the assignment
of proper radiological controls.
SUMMARY
HP210, SH-4 and ESP Laboratory Counter
Detector type: GM
Detector shield: Tungsten for gamma, or aluminum for beta
Detector window: mica 1.4 to 2 mg/cm2
Radiation detected: beta
Controls: ESP (see lesson 2.17)
Source check: Sr-90
Eberline SAC–4 Laboratory Counter
Detector type: ZnS(Ag) scintillator
Detector shield: None
Detector window: None
Radiation detected: alpha
Controls: Timer: 0.1 to 50 minutes
Source check: NIST traceable Pu-239 source
NMC PC–5, PC-55 Laboratory Counter
Detector type: Gas flow proportional counter (P-10 gas)
Detector shield: None
Section 166
Detector window: None, or optional 0.25 mils plastic (1 mg/cm2)
Radiation detected: alpha
Controls: Timer 0.1 minute to 1000 minutes
Source check: NIST traceable Pu-239 source
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Module 2.19 Counting Room Equipment Study Guide
2.19-12
Canberra 2400 Low-Background Automatic
Detector type: Gas flow proportional detector (P-10 gas).
Larger guard detector for background.
Optional NaI detector for gammas.
Detector shield: 4 inches lead
Detector window: 0.25 mil mylar (1 mg/cm2)
Radiation detected: alphas and betas
Optional NaI detector for gammas
Source checks: Pu-239, Sr-90, and Tc-99.
Berthold LB770 Low-Background Automatic
Detector type: 10 gas flow proportional counters (P-10 gas).
Plus one detector to count background.
Detector shield: 4 inches of epoxy coated lead
Detector window: 0.25 mil mylar (1 mg/cm2)
Radiation detected: alphas and betas
Source check: NIST traceable Pu-239 calibration source for alpha and
90Sr/Y90 for beta
Liquid Scintillation Counter
Packard 2550 Low-Background Automatic
Detector type: Liquid scintillation
Detector shield: none
Detector window: none (Light tight housing)
Radiation detected: Low energy beta from Tritium (or C-14)
Source checks: LANL calibration sources, with water as quench agent.
EG&G Ortec Gamma-X Gamma Spectroscopy
Detector type: HPGe (high purity germanium)
Detector shield: 4 inches pre WW-II steel or 4 inches of coated lead.
Detector window: Beryllium window 0.5 mm thick
Radiation detected: gamma and x-ray photons from 3 keV to 4MeV
Source checks: NIST traceable mixed sources:
GLOSSARY:
cocktail: mixture of liquid scintillation chemicals and sample
discriminator: electronic device that discriminates against small pulses, e.g. to
distinguish alphas from betas.
gamma spectroscopy: the use of gamma spectra to identify radionuclides by their
characteristic gamma emissions.
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multi channel analyzer (MCA): combination of many SCAs, each connected to a
scaler channel, to produce a spectrum
resolution: measure of the ability of a system to separate nearby peaks in a
spectrum; measure of the widths of the peaks.
single channel analyzer (SCA): combination of a lower level discriminator and an
upper level discriminator to select only pulses between the two levels (e.g. to
select betas but reject small pulse height noise and large pulse height alphas).