Frequently Asked Questions DOE-STD-3009-2014

DOE-STD-3009-2014 Frequently Asked Questions - 1 - Q1: Why was DOE-STD-3009 revised? A1: The goal of this revised Standard is to provide clearer criteria and guidance to support effective and consistent Documented Safety Analyses (DSAs) based upon lessons learned in implementing DOE-STD-3009-94. DOE has gained over 20 years of experience and lessons learned in implementing DOE-STD-3009-94. DOE also committed to revise DOE-STD-3009 in response to DNFSB Recommendation 2010-1. Q2: What are the major changes in DOE-STD-3009-2014? A2: This revision: • Clarifies use of the Evaluation Guideline; • Clarifies use of bounding parameters; • Clarifies unmitigated and mitigated hazard evaluations to protect the workers, public, and environment; • Clarifies standard industrial hazards and chemical hazards screening or further hazard evaluation; • Establishes a clear criterion for use of the hierarchy of controls and requires documentation of the rationale; • Clarifies major contributors to defense-in-depth for selection of safety significant controls; • Incorporates methodologies for co-located workers and chemical hazard evaluations; • Refines methods for air dispersion calculations; • Provides specific criteria for determining the functional adequacy of safety class and safety significant structures, systems, and components; and • Reduces the level of description required in DSAs for safety management programs. Q3: Does 10 C.F.R. Part 830 require use of DOE-STD-3009-2014 for existing DOE nuclear facilities? A3: No. 10 C.F.R. Part 830 requires contractors for DOE nuclear facilities to use a safe harbor standard for preparing DSAs, or to obtain approval of an alternate methodology. DOE-STD- 3009 is the most-used safe harbor standard, and many existing DOE nuclear facilities use DOE- STD-3009-94. The 10 Code of Federal Regulations (C.F.R.) 830 safe harbor table requires use of “DOE-STD-3009-94, Change Notice No. 1 … or successor document.” However, in an October 18, 2014 letter, the Secretary of Energy reiterated the following commitment for an evaluation of existing defense nuclear facilities relative to the new revision of DOE-STD-3009: “In addition, as stated in Section 6.2 of the Department's 2010-1 IP, the evaluation of DSAs for existing defense nuclear facilities relative to the new revision of DOE-STD-3009 will be performed consistent with the current regulatory process for developing and maintaining DSA updates. This evaluation will look for and implement enhancements that can be made based upon lessons learned and best practices that have been incorporated in DOE-STD-3009-2014 Frequently Asked Questions - 2 - the revised DOE-STD-3009, related to protection of the public from nuclear hazards. The Department is in the process of developing its approach for this evaluation.” Q4: In what circumstances should major modifications to existing DOE nuclear facilities use the new DOE-STD-3009-2014? A4: DOE O 420.1C Page Change 1 (approved February 27, 2015) requires use of DOE-STD- 3009-2014 for preparing documented safety analyses for major modifications to existing nuclear facilities, when the DOE-STD-3009 method is used as the safe harbor method to satisfy 10 C.F.R. Part 830, Nuclear Safety Management, requirements. For such major modifications to existing non-reactor nuclear facilities, DOE O 420.1C Page Change 1 also allows the appropriate

Secretarial Officers, with concurrence by the applicable Central Technical Authority, to approve use of DOE-STD-3009-94. This PSO-approved exception is expected to be used for relatively smaller modifications, particularly those that do not add major new types of equipment or major new accidents. This PSO-approved exception is not expected to be used when major new structures or major new accident scenarios are added to existing facilities. Q5: When a major modification to an existing facility uses the new DOE-STD-3009-2014, does the whole DSA have to be upgraded to the new STD-3009? A5: No, not necessarily. Existing nuclear facilities undergoing a major modification are allowed to continue to use existing DOE-STD-3009-94, with approval by the appropriate Secretarial Officer and concurrence by the applicable Central Technical Authority. As described in A5, the approach should be based on the relative size and significance of the modification. It may be possible to use the requirements of the new DOE-STD-3009-2014 for design of the major modification, but not upgrade the overall DSA to the new standard. Q6: What does STD-3009 say about "Equipment Important to Safety"? A6: DOE-STD-3009-2014 says nothing about “Equipment Important to Safety.” The Standard only recognizes three classifications of hazard controls: (1) Safety Class, (2) Safety Significant, and (3) Other Hazard Controls. 10 C.F.R. 830 does not use the term “Equipment Important to Safety” in reference to DSA preparation. This is a consideration for unreviewed safety question determinations, as described in the DOE Guide G 424.1-1B, and additional clarifications are being considered for the next revision to that Guide. Q7: When using Option 1, is it acceptable to use either the 95th percentile directionally independent or the 99.5th percentile directionally dependent X/Q, even though this is not consistent with NRC Reg. Guide 1.145? A7: Yes. In Section 3.2.4.2, under the heading “Determination of the Offsite χ/Q,” the Standard states: “While the three options allow for alternative methods to calculate the χ/Q values, all three options shall evaluate the dose at the MOI using either a 95th percentile for a directionally DOE-STD-3009-2014 Frequently Asked Questions - 3 - independent method or a 99.5th percentile for a directionally dependent method. Option 1 is based on Reg. Guide 1.145; it is not a verbatim compliance to Reg. Guide 1.145. Q8: Can the directionally independent 95th percentile X/Q credit irregular site boundary distances? A8: Yes. The analysis is intended to be consistent with the NRC Regulatory Guide 1.145 determination of the “5 percent overall site” X/Q (i.e., 95th percentile) considering variable site boundaries as defined by Regulatory Position 3. The term "directionally independent" as used in STD-3009-2014 means that the determination of the overall site 95th percentile χ/Q is calculated by creating a cumulative probability distribution for all sectors combined based on all the meteorological annual data and using the actual site boundary distance for each sector. See also Q&A 11 below. Q9: Regarding the Option 2 X/Q method, can the DOE Toolbox version of MACCS2 be applied, since it is not fully compliant with the NRC Regulatory Guide 1.145 methodology? A9: Yes. Historically, MACCS2 has been used to calculate the offsite 95th percentile X/Q for

DOE facilities despite the fact that the methodology used does not take into account variations in site boundary distances. As stated in DOE-EH-4.2.1.4-MACCS2-Code Guidance (June 2004), MACCS2 Computer Code Application Guidance for Documented Safety Analysis: “MACCS2 and MACCS do not comply fully with … (NRC Regulatory Guide 1.145 Position 3) methodology for determination of direction-independent 95th percentile dose to the offsite individual. It may be used to conservatively evaluate the 95th percentile direction-independent dose to receptors equidistant to the source.” “Given site-specific data, the 95th percentile consequence is determined from the distribution of meteorologically-based doses calculated for a postulated release to downwind receptors at the site boundary that would result in a dose that is exceeded 5% of the time. [DOE-STD-3009] allows for variations in distance to the site boundary as a function of distance to be taken into consideration. Assuming the minimum distance to the site boundary applies in all directions is a conservative implementation that is easily supported by MACCS2 and that essentially makes the calculations sector independent.” Q10: In Section 3.2.4.2 of DOE-STD-3009-2014, what is intended by the term “recent” in relationship to meteorological data? Does this imply some expected periodicity? A10: In this context, “recent” means within ten years. Regarding the implied periodicity in the term "recent," with respect to meteorological data and analysis for X/Q, the forthcoming Accident Analysis Handbook will recommend a reanalysis of X/Q every ten years. The five- years average is expected to change slowly over time and there is no need for more frequent reanalysis. Q11: In Section 3.3.1 of DOE-STD-3009-2014, what is intended by the following sentence: “Further, it is DOE’s goal that the combined effectiveness of the suite of SC and/or SS controls DOE-STD-3009-2014 Frequently Asked Questions - 4 - will be such that accident consequences would be well below the EG”? Does DOE expect this goal to be demonstrated in the DSA? A11: The cited sentence is merely a description of DOE’s goal; it does not contain or imply any requirements. The primary requirement in this Section is that the DSA demonstrate how SC SSCs or SACs mitigate consequences of anticipated accidents below the EG, when preventive controls do not terminate the scenario or eliminate the hazard. Beyond that, the cited sentence permits consideration of other SS controls (i.e., entire suite of SC and SS) to achieve the goal of consequence reduction “well below the EG.” Q12: In Section 3.3.1 of DOE-STD-3009-2014, what is intended by the following sentence: “If unmitigated off-site doses between 5 rem and 25 rem are calculated (i.e., challenging the EG), SC controls should be considered, and the rationale should be described for decisions on whether or not to classify controls as SC”? Does this sentence describe a requirement? Will DOE reviewers of DSAs turn this sentence into a requirement? A12: The cited sentence is a recommendation, not a requirement. The standard clearly defines the use of “shall” for requirements and “should” for recommendations. The phrasing of this sentence is also consistent with that in DOE-STD-1189-2008 for new facilities and major modifications. The intent is to consider SC controls or provide DOE with the rationale when not

establishing SC controls for accidents with consequences between 5 and 25 rem. This is to help in establishing a basis for risk acceptance (e.g., consequence calculations have multiple conservatisms that don’t warrant SC controls, etc.) In general, DOE expects that DOE-STD- 3009-2014 will provide for more consistent and conservative consequence calculations based on clear requirements, and therefore the EG of 25 rem serves as the appropriate “bright line” criterion for determining SC categorization for hazard controls. Q13: Section 3.3.1 of DOE-STD-3009-2014 provides a requirement for new nuclear facilities that SC controls shall be applied to prevent identified accidents or mitigate consequences to below the EG of 25 rem. DOE-STD-5506-2007 (Section 6.3) states that doses greater than 10 rem should be considered sufficient to challenge the EG. How do these compare and which takes precedence? A13: First, DOE-STD-5506 is a supplemental standard to the safe-harbors of 10 C.F.R. 830. It is expected that the standard will be revised in the future to reflect lessons learned captured in DOE-STD-3009-2014. As it is the primary safe harbor, DOE-STD-3009-2014 takes precedence. The two standards differ only slightly regarding thresholds for “challenging” the EG. DOE- STD-3009-2014 indicates that 5 to 25 rem is the range for “challenging the EG,” whereas STD- 5506 identifies a 10 rem threshold. However, and more important, DOE-STD-3009-2014 clearly establishes the SC control threshold at the EG of 25 rem. See also Q&A 14 above. Q14: DOE-STD-3009-2014 states that hazard evaluation data are part of the DSA, whether included directly or by reference. The standard further states that “For each hazard scenario, hazard evaluation tables or data sheets document the following; … Available preventive and mitigative controls.” If “available preventive and mitigative controls” are identified in the hazard evaluation tables or data sheets, and these are considered part of the DSA, does DOE DOE-STD-3009-2014 Frequently Asked Questions - 5 - expect that all “available” controls identified in these tables will be controlled, managed, and updated using the USQ process, even where such controls do not rise to the level of SC or SS? A14: Yes, to the degree that one of the controls is involved with a “proposed change” as described in 10 C.F.R. Part 830 and DOE G 424.1-1B, or is somehow related to a discovery of a Potential Inadequacy in the Safety Analysis (PISA). While major contributors to defense-in- depth are identified as SS, other hazard controls that are not identified as either SC or SS are also important as they contribute to the overall defense-in-depth approach that is required for DOE nuclear facilities. Q15: In performing the mitigated analysis to determine effectiveness of safety-significant co- located worker safety controls, as required by Section 3.2.3 of DOE-STD-3009-2014, are quantitative calculations required for each hazard scenario to report mitigated dose estimates? A15: No. Footnote 4 of Table 1 in Section 3.1.3.1 states: “Although quantitative thresholds are provided for the MOI and co-located worker consequences, the consequences may be estimated using qualitative and/or semi-quantitative techniques.” As an example, an acceptable approach would be to perform a quantitative calculation for worst case scenarios, and then demonstrate qualitatively how these results are bounding for other scenarios. For example, the analysis

would quantitatively calculate the unmitigated consequences to the MOI and co-located worker and then could semi-quantitatively or qualitatively state that an installed, credited 99.9% efficient HEPA filter system that provides a 1E-3 reduction in consequences would clearly reduce consequences to less than the EG. Results of the hazard evaluation, and the effectiveness of hazard controls as used in specific hazard scenarios may be shown qualitatively in the hazard evaluation tables. Alternately, the quantitative estimates of mitigated dose when crediting mitigative controls may be shown on the hazard evaluation tables and/or hazard evaluation summary of results. Q16: If a facility DSA uses quantitative calculations to assign qualitative likelihood estimates during hazard evaluation, does application of the revised DOE-STD-3009-2014 require application of DOE-STD-1628-2013, Development of Probabilistic Risk Assessments for Nuclear Safety Applications? A16: No, not necessarily. The standard (Section 3.1.3.1) does require selection and justification of appropriate hazard evaluation techniques, including Fault Tree Analysis and Event Tree Analysis. Use of these techniques typically involves quantitative calculations. Section 3.1.3.1 specifically allows use of “quantitative calculations” appropriate to assign qualitative likelihood estimates. The conditional requirement in DOE-STD-3009-2014 requiring application of DOE- STD-1628-2013 is applicable only if the facility elects to use of a complete probabilistic risk assessment (PRA) as described in DOE-STD-1628-2013. DOE-STD-1628-2013 states that “it is not intended for analysis that simply employs a subset of PRA techniques, such as event-tree or fault-tree analysis.” PRAs are defined in DOE-STD-1628-2013 as an “assessment of the risk associated with plant or facility operation and maintenance that is measured in terms of frequency of occurrence of risk metrics, such as release category frequency and its effects on the health of the public [also referred to as a probabilistic safety assessment (PSA) or quantitative DOE-STD-3009-2014 Frequently Asked Questions - 6 - risk assessment (QRA)].” If this full PRA technique is used to support DOE safety analysis, then the provisions of DOE-STD-1628-2013 would apply. Q17: In Section 3.1.3.1, 1st paragraph below Table 2 states “Risk ranking/binning may be used to support the selection of Design Basis Accidents (DBAs)/ Evaluation Basis Accidents (EBAs) and hazard controls (See Appendix A, Section A.4 for information on risk ranking/ binning).” However, Section A.4 does not provide guidance on the use of risk ranking for hazard controls. Will there be guidance provided in the near future? A17: Section A.4 provides additional guidance on a risk ranking methodology but does not further elaborate on the use for selection of hazard controls as described in Section 3.1.3.1. Additional guidance on the use of risk ranking for control selections will be included in the draft Accident Analysis Handbook, based on methodologies similar to those presented in the DOE- STD-5506-2007, Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities, and DOE-STD-1120-2005, Integration of Environment, Safety, and Health into Facility Disposition Activities. Both of these standards are based on using qualitative unmitigated risk estimates as another input to the process to determine when to select safety significant SSCs

or SACs. The intent is to provide a qualitative tool to facilitate discussion between cognizant subject matter experts, including facility and operational staff, and the DOE to enhance the judgment process inherent to selection of hazard controls. Q18: DOE-STD-3009-2014, Appendix A.2 provides a list of examples of chemicals that may be excluded from DSA hazard evaluations. Is it allowable that chemicals that exceed these screening criteria may be excluded from further qualitative or quantitative hazard evaluation? A18: Yes, chemicals that exceed the Appendix A.2 screening criteria may be screened out as discussed below. Table 9-1 of Section 9.3, Chemical Screening Criteria, of DOE-HDBK-1224-2018, Hazard and Accident Analysis Handbook, presents additional considerations regarding screening criteria. The use of these screening criteria may be an initial step in the screening process. Chemicals that do not meet those screening criteria thresholds may be screened against the discussion in the introduction of DOE-STD-3009-2014 Section A.2, which states: The DSA is not intended to deal extensively with chemicals that can be safely handled by implementation of a hazardous material protection program. Therefore, a screening process is established to select for DSA evaluation only those chemicals of concern (i.e., type and quantity that have the potential for significant health effect on the facility worker, co-located worker, or public) that are present in the facility or activity and present hazard potentials outside the routine scope of the hazardous material protection program. Therefore, if the chemical hazard potential is adequately evaluated and controlled by the routine scope of the hazardous material protection program, meeting the requirements of 10 CFR Part 851, Worker Safety and Health Program, the chemical may be screened out from further hazard evaluation in the DSA. DOE-STD-3009-2014 Frequently Asked Questions - 7 - However, there still may be other considerations that warrant further evaluation of the chemical in the DSA hazard evaluation. DOE-HDBK-1224-2018 Section 2.2.4, Exclusion of Standard Industrial Hazards and Other Hazardous Materials, provides these additional clarifications. This statement is reproduced, in part, as follows: The DSA hazard evaluation scope covers analysis of: (a) hazardous chemicals affecting nuclear safety; and, (b) in some cases, chemical hazards that are outside the scope of the facility’s hazardous material protection program. The intent of DOE-STD-3009-2014 is to cover: • Radiation-related hazardous chemical events (examples: chemicals comingled with radiological waste, chemicals generated through radiological processes, and chemicals generated or released through processing of radioactive materials); • Nuclear safety-related hazardous chemical events (examples: events that affect a worker relied upon for a credited action, events that affect safety-related SSCs through corrosion, fire, or explosion); or • Unique hazardous chemical events, not addressed by 10 CFR Part 851, that could cause harm to workers, the public or the environment. Section 2.2.4 of DOE-HDBK-1224-2018 also includes additional guidance regarding screening chemicals out, and evaluating chemicals further in the hazard evaluation. This includes a screening example of a large outside storage tank, guidance for unmitigated consequence

assessment for the facility worker, and the need to address the unique hazard of asphyxiation as discussed in DOE-STD-3009-2014 Section A.1. In addition, per DOE-STD-3009-2014 Section A.2, chemicals “that could otherwise be screened out, but have the potential to be an accident initiator involving radioactive or hazardous material releases, or could compromise the ability of the facility operators to safely manage the facility, are retained as part of the DSA hazard evaluation.” Lastly, DOE-HDBK-1224-2018 Section 2.3.3, Chemical Hazard Evaluation, provides additional guidance to the discussion in DOE-STD-3009-2014 Section 3.1.3.4, Chemical Hazards, regarding further qualitative hazard evaluation. That Handbook section also references other sections regarding a quantitative assessment as discussed in the DOE-STD-3009-2014 Section 3.2.3.4, Chemical Source Term and Consequence, and Appendix A.2 method to estimate exposure concentration for comparison to safety significant thresholds for control selection.