DOE-HDBK-1122-99 Module 1.02, Fundamental Academic Training Instructor's Guide Phase I; Module 1.02, Instructor's Guide - Unit Analysis and Conversion
Functional areas: Radiological Control, Technician Training, Instructor's Guide, Unit Analysis, Conversion
A knowledge of the unit analysis and conversion process is a necessity for the RCT. It is useful for air and water sample
activity calculations, contamination calculations, and many other applications.
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Section 1
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Module 1.02 Unit Analysis & Conversion Instructor’s Guide
1.02-1
Course Title: Radiological Control Technician
Module Title: Unit Analysis & Conversion
Module Number: 1.02
Objectives:
1.02.01 Identify the commonly used unit systems of measurement and the base units for
mass, length, and time in each system.
1.02.02 Identify the values and abbreviations for SI prefixes.
1.02.03 Given a measurement and the appropriate conversion factor(s) or conversion
factor table, convert the measurement to the specified units.
1.02.04 Using the formula provided, convert a given temperature measurement to
specified units.
References:
1. "Health Physics and Radiological Health Handbook"; Scinta, Inc; 1989.
2. DOE-HDBK-1010-92 (June 1992) "Classical Physics" DOE Fundamental Handbook; US
Department of Energy.
3. "Nuclides and Isotopes"; Fourteenth Edition, General Electric Company; 1989.
4. "Chemistry: An Investigative Approach"; Houghton Mifflin Co., Boston; 1976.
5. "Introduction to Chemistry: sixth ed.; Dickson, T. R.; John Wiley & Sons, Inc.; 1991.
6. "Physics"; 2nd ed.; Giancoli, Douglas C.; Prentice Hall, Inc.; 1985.
7. "Modern Physics"; Holt, Rinehart and Winston, Publishers; 1976.
8. NIST Special Publication 330; "The International System of Units" National Institute of
Standards and Technology; 1991.
Instructional Aids:
1. Overheads
2. Overhead projector/screen
3. Chalkboard/whiteboard
4. Lessons Learned
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Module 1.02 Unit Analysis & Conversion Instructor’s Guide
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I. MODULE INTRODUCTION
A. Self Introduction
1. Name
2. Phone number
3. Background
4. Emergency procedure review
B. Motivation
A knowledge of the unit analysis and conversion process is a
necessity for the RCT. It is useful for air and water sample
activity calculations, contamination calculations, and many
other applications.
C. Overview of Lesson
1. Units
2. Unit systems
3. Unit analysis and conversions including use of conversion
factor tables
D. Introduce Objectives O.H.: Objectives
II. LESSON OUTLINE
A. Units and Measurements
1. Units are used to express physical quantities or
measurements, i.e., length, mass, etc. All measurements
are actually relative in the sense that they are comparisons
with some standard unit of measurement. Two items are
necessary to express these physical quantities:
a. A number--expresses the magnitude.
b. A unit--expresses the dimension.
2. A number and a unit must both be present to define a
measurement.
3. Measurements are algebraic quantities and as such may be
mathematically manipulated subject to algebraic rules.
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4. Fundamental Quantities
All measurements or physical quantities can be expressed
in terms of three fundamental quantities. They are called
fundamental quantities because they are dimensionally
independent. They are:
See Fig. 1 in the Study
Guide - "Fundamental
Units"
a. Length (L)
b. Mass (M) (not the same as weight)
c. Time (T)
5. Derived Quantities
Other quantities are derived from the fundamental
quantities. These derived quantities are formed by
multiplication and/or division of fundamental quantities.
For example:
a. Area is the product of length times length (width),
which is L × L, or L2.
b. Volume is area times length, which is length times
length times length, or L3.
c. Velocity is expressed in length per unit time, or L/T.
d. Density is expressed in mass per unit volume, or M/L3.
Section 2
B. Systems of Units Objective 1.02.01
1. The units by which physical quantities are measured are
established in accordance with an agreed standard.
Measurements made are thereby based on the original
standard which the unit represents. The various units that
are established, then, form a system by which all
measurements can be made.
2. English System See Table 1 of the Study
Guide - "English System
Base Units"
a. The system that has historically been used in the
United States is the English System, sometimes called
the English Engineering System (EES). Though no
longer used in England, many of the units in this
system have been used for centuries and were
originally based on common objects or human body
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parts, such as the foot or yard. Though practical then,
the standards for these units were variable as the
standard varied from object to object, or from person
to person.
b. Even though fixed standards have since been
established for these antiquated units, no uniform
correlation exists between units established for the
same quantity. For example, in measuring relatively
small lengths there are inches, feet, and yards. There
are twelve inches in a foot, and yet there are only three
feet in a yard. This lack of uniformity makes
conversion from one unit to another confusing as well
as cumbersome. However, in the U.S., this system is
still the primary system used in business and
commerce.
3. International System of Units (SI)
a. Since the exchange of scientific information is world-
wide today, international committees have been set up
to standardize the names and symbols for physical
quantities.
b. In 1960, the International System of Units
(abbreviated SI from the French name Le Système
Internationale d'Unites) was adopted by the 11th
General Conference of Weights and Measures
(CGPM).
c. The SI, or modernized metric system, is based on the
decimal (base 10) numbering system. First devised in
France around the time of the French Revolution, the
metric system has since been refined and expanded so
as to establish a practical system of units of
measurement suitable for adoption by all countries.
The SI system consists of a set of specifically defined
units and prefixes that serve as an internationally
accepted system of measurement. Nearly all countries
in the world use metric or SI units for business and
commerce as well as for scientific applications.
4. SI Prefixes Objective 1.02.02
a. The SI system is completely decimalized and uses
prefixes for the base units of meter (m) and gram (g),
as well as for derived units, such as the liter (l) which
equals 1000 cm3.
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b. SI prefixes are used with units for various magnitudes
associated with the measurement being made. Units
with a prefix whose value is a positive power of ten
are called multiples. Units with a prefix whose value
is a negative power of ten are called submultiples.
See Table 2 of the Study
Guide - "SI Prefixes"
c. For example, try using a yard stick to measure the size
of a frame on film for a camera. Instead you would
use inches, because it is a more suitable unit. With the
metric system, in order to measure tiny lengths, such
as film size, the prefix milli- can be attached to the
meter unit to make a millimeter, or 1/1000 of a meter.
A millimeter is much smaller and is ideal in this
situation. On the other hand, we would use a prefix
like kilo- for measuring distances traveled in a car. A
kilometer would be more suited for these large
distances than the meter.
Section 3
d. Prior to the adoption of the SI system, two groups of
units were commonly used for the quantities length,
mass, and time: MKS and CGS.
See Table 3 in the Study
Guide - "Metric
Subsystems"
5. SI Units
a. There are seven fundamental physical quantities in the
SI system. These are length, mass, time, temperature,
electric charge, luminous intensity, and molecular
quantity (or amount of substance). In the SI system
there is only one SI unit for each physical quantity.
The SI system base units are those in the metric MKS
system. Table 4 in the Study Guide lists the seven
fundamental quantities and their associated SI unit.
The units for these seven fundamental quantities
provide the base from which the units for other
physical quantities are derived.
See Table 4 in the Study
Guide - "International
System (SI) Units"
b. For most applications the RCT will only be concerned
with the first four quantities as well as the quantities
derived from them.
6. Radiological Units
In the SI system, there are derived units for quantities used
for radiological control. These are the becquerel, the gray,
and the sievert. The SI unit of activity is the becquerel,
which is the activity of a radionuclide decaying at the rate
of one spontaneous nuclear transition per second. The
gray is the unit of absorbed dose, which is the energy per
unit mass imparted to matter by ionizing radiation, with the
units of one joule per kilogram. The unit for dose
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equivalence is the sievert, which has units of joule per
kilogram. These quantities and their applications will be
discussed in detail in Lesson 1.06.
7. Other units
There are several other SI derived units that are not listed
in Table 4 of the Study Guide. It should be noted that the
SI system is evolving and that there will be changes from
time to time. The standards for some fundamental units
have changed in recent years and may change again as
technology improves our ability to measure even more
accurately.
C. Unit Analysis and Conversion Process Objective 1.02.03
1. Units and the Rules of Algebra
a. Remember that a measurement consists of a number
and a unit. When working problems with
measurements, it should be noted that the
measurement units are subject to the same algebraic
rules as the values. Some examples are provided
below.
(cm) × (cm) � cm 2
ft 3
ft
� ft 2
1
yr
� yr �1
b. As a result, measurements can be multiplied, divided,
etc., in order to convert to a different system of units.
Obviously, in order to do this, the units must be the
same. For example, a square measures one foot in
length and 18 inches in width. To find the area of the
square in square inches we must multiply the length by
the width. However, when the measurements are in
different units, and cannot be multiplied directly.
c. We can convert feet to inches. We know that there are
12 inches in one foot. We can use this ratio to convert
1 foot to 12 inches. Then we can then calculate the
area as 12 inches × 18 inches, which equals 216 in2,
which is a valid measurement.
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2. Steps for Unit Analysis and Conversion
a. Determine given units and desired units.
b. Build (or obtain) conversion factor(s) -- see
Conversion Tables at end of lesson.
Section 4
1) A conversion factor is a ratio of two equivalent
physical quantities expressed in different units.
When expressed as a fraction, the value of all
conversion factors is 1. Because a conversion
factor equals 1, it does not matter which value is
placed in the numerator or denominator of the
fraction.
2) Examples of conversion factors are:
365 days
1 year
12 inches
1 foot
1 foot 3
2.832E4 cm 3
3) Building conversion factors involving the metric
prefixes for the same unit can be tricky. This
involves the conversion of a base unit to, or from,
a subunit or superunit.
4) To do this, use the following steps:
Example: 1 gram to milligrams
a) Place the base unit in the numerator and the
subunit/ superunit in the denominator (or
vice versa):
g
mg
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1E�2m
1cm
�
1m
100cm
b) Place a 1 in front of the subunit/superunit:
g
1 mg
c) Place the value of the prefix on the subunit/
superunit in front of the base unit:
m (milli-) = 10-3 or 1E-3
1E�3 g
1 mg
5) Also remember that algebraic manipulation can be
used when working with metric prefixes and
bases. For example, 1 centimeter = 10-2 meters.
This means that 1 meter = 1/10-2 centimeters, or
100 cm. Therefore, the two conversion factors
below are equal:
c. Set up an equation by multiplying the given units by
the conversion factor(s) to obtain desired unit(s).
1) When a measurement is multiplied by a
conversion factor, the unit(s) (and probably the
magnitude) will change; however, the actual
measurement itself does not change. For
example, 1 ft and 12 inches are still the same
length; only different units are used to express the
measurement.
2) By using a "ladder" or "train tracks," a series of
conversions can be accomplished in order to get
to the desired unit(s). By properly arranging the
numerator and denominator of the conversion
factor(s), given and intermediate units will cancel
out by multiplication or division, leaving the
desired units. Some examples of the unit analysis
and conversion process follow:
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3 years� 365.25 days�
1 year�
24 hours�
1 day�
60 minutes�
1 hour�
60 seconds
1 minute�
� 94,672,800 sec.
3. Example 1: Convert 3 years to seconds.
Step 1 - Determine given and desired unit(s):
Given units: years
Desired units: seconds.
Step 2 - Build/obtain conversion factor(s):
We can use multiple conversion factors to accomplish
this problem:
1 year = 365.25 days
1 day = 24 hours
1 hour = 60 minutes
1 minute = 60 seconds
Step 3 - Analyze and cancel given and intermediate units.
Perform multiplication and division of numbers:
4. Example 2: What is the activity of a solution in if it
µCi
ml
has 2000 ?
dpm
gallon
Step 1 - Determine given and desired unit(s):
Given units:
dpm
gallon
Desired units:
µCi
ml
Step 2 - Build conversion factor(s):
1 liter = 0.26418 gallons
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2000 dpm�
gal�
4.5E�7 µCi
1 dpm�
0.26418 gal�
1 ��
1 ��
1,000 ml
� 2.38E�7 µCi
ml
1 dpm = 4.5 E-07 µCi
1 liter = 1000 ml
Step 3 - Analyze and cancel given and intermediate units.
Perform multiplication and division of numbers.
D. Temperature Measurements and Conversions Objective 1.02.04
Section 5
1. Temperature measurements are made to determine the
amount of heat flow in an environment. To measure
temperature it is necessary to establish relative scales of
comparison. Three temperature scales are in common use
today. The general temperature measurements we use on a
day-to-day basis in the United States are based on the
Fahrenheit scale. In science, the Celsius scale and the
Kelvin scale are used.
See Fig. 2 in the Study
Guide - "Comparison of
Kelvin, Celsius and
Fahrenheit scales"
2. The Fahrenheit scale, named for its developer, was devised
in the early 1700's. This scale was originally based on the
temperatures of human blood and salt-water, and later on
the freezing and boiling points of water. Today, the
Fahrenheit scale is a secondary scale defined with
reference to the other two scientific scales. The symbol °F
is used to represent a degree on the Fahrenheit scale.
3. About thirty years after the Fahrenheit scale was
developed, Anders Celsius, a Swedish astronomer,
suggested that it would be simpler to use a temperature
scale divided into one hundred degrees between the
freezing and boiling points of water. For many years his
scale was called the centigrade scale. In 1948 an
international conference of scientists re-named it the
Celsius scale in honor of its inventor. The Celsius degree,
°C, was defined as 1/100 of the temperature difference
between the freezing point and boiling point of water.
4. In the 19th century, an English scientist, Lord Kelvin,
established a more fundamental temperature scale that
used the lowest possible temperature as a reference point
for the beginning of the scale. The lowest possible
temperature, sometimes called absolute zero, was
established as 0 K (zero Kelvin). This temperature is
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273.15°C below zero, or -273.15°C. Accordingly, the
Kelvin degree, K, was chosen to be the same as a Celsius
degree so that there would be a simple relationship
between the two scales.
5. Note that the degree sign (°) is not used when stating a
temperature on the Kelvin scale. Temperature is stated
simply as Kelvin (K). The Kelvin was adopted by the 10th
Conference of Weights and Measures in 1954, and is the
SI unit of thermodynamic temperature. Note that the
degree Celsius (°C) is the SI unit for expressing Celsius
temperature and temperature intervals. The temperature
interval one degree Celsius equals one kelvin exactly.
Thus, 0°C = 273.15 K by definition.
6. To convert from one unit system to another, the following
formulas are used:
See Table 5 in the Study
Guide - "Equations for
Temperature
Conversions"
1) �C �
(�F�32)
1.8
or
�C � (�F�32) 5
9
2) �F � 1.8(�C) � 32
or
�F �
9
5
(�C) � 32
3) K � �C � 273.15
7. Example 3: Convert 65° Fahrenheit to Celsius:
�C �
(65�F� 32)
1.8
�C �
33
1.8
�C � 18.3�C
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III. SUMMARY
A. Review major topics
1. Units
2. Unit systems
3. Unit analysis and conversions including use of conversion
factor tables
B. Review learning objectives
IV. EVALUATION
Evaluation should consist of a written examination comprised of
multiple choice questions. 80% should be the minimum passing
criteria for the examination.
Module Number: 1.02