DOE-STD-5506-2021, Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities

DOE-STD-5506-2021 AUGUST 2021 DOE STANDARD Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities U.S. Department of Energy Washington, D.C. 20585 AREA-SAFT DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. DOE-STD-5506-2021 Available on the Department of Energy Technical Standards Program Web Site at standards.doe.gov http://standards.doe.gov i DOE-STD-5506-2021 Foreword This Standard provides analytical assumptions and methods, as well as hazard controls to be used when developing Safety Basis documents for transuranic (TRU) waste facilities in the U.S. Department of Energy (DOE) Complex. This Standard complements the safe harbor methods in Appendix A to Subpart B of 10 CFR Part 830 (Nuclear Safety Management). It also provides supplemental technical information that is specific to TRU waste operations, so Federal employees and contractors can formulate, implement, and maintain safety bases for TRU waste operations in a consistent manner that is compliant with 10 CFR Part 830, Subpart B, requirements. The information contained in this Standard is intended for use by all Department of Energy (DOE) and National Nuclear Security Administration (NNSA) sites and all contractors for DOE-owned or DOE- leased, Hazard Category 1, 2, or 3 nuclear facilities or nuclear operations that involve generation, handling, storage, and remediation of TRU waste. It may also be applied to these facilities having low- level waste. Beneficial comments (recommendations, additions, and deletions), as well as any pertinent data that may be of use in improving this document, should be emailed to NuclearSafety@em.doe.gov or addressed to: Office of Safety, Security, and Quality Assurance (EM-3.1) Office of Environment Management U.S. Department of Energy 1000 Independence Ave, SW Washington, DC 20585 The need for an existing, approved TRU waste facility Documented Safety Analysis (DSA) to be revised or revisited in light of the issuance of this Standard is addressed in Section 1.6; that decision will be made by the applicable DOE or NNSA program office and their Safety Basis Approval Authority for the facility. However, if a facility, site, or program office is required to, or chooses to, use this DOE- STD-5506-2021 for revising an existing DSA, then this Standard requires that all applicable “shall” statements be met if it is used to supplement the applicable “safe harbor” method from 10 CFR 830 Subpart B that is used for development of the DSA. mailto:NuclearSafety@em.doe.gov DOE-STD-5506-2021 ii Table of Contents Section Page Foreword ......................................................................................................................................... i Figures ......................................................................................................................................... viii Tables ............................................................................................................................................. ix Introduction .............................................................................................................................1 1.1 Background ...............................................................................................................................1 1.2 Scope .........................................................................................................................................1

1.3 Purpose .....................................................................................................................................2 1.4 Applicability .............................................................................................................................2 1.5 Use of the Words Shall and Should ..........................................................................................3 1.6 Overview of Changes in this Revision .....................................................................................3 Acronyms .................................................................................................................................5 Identification and Evaluation of TRU Waste Events ..........................................................8 3.1 Purpose .....................................................................................................................................8 3.2 Hazard Identification and Standard Industrial Hazard Screening ............................................8 3.3 TRU Waste Operations Minimum Set of Accidents ...............................................................10 3.3.1 Fire Events ................................................................................................................12 Fuel Pool Fires (Event 1) .........................................................................................12 Small Fire (Event 2) .................................................................................................13 Enclosure Fire (Event 3) ..........................................................................................13 Large Fire (Event 4) .................................................................................................13 3.3.2 Explosion Events ......................................................................................................14 Ignition of Fumes Results in an Explosion (external to container) (Event 5) ..........14 Waste Container Deflagration (Event 6) ..................................................................14 Multiple Waste Container Deflagration (Event 7)....................................................15 Enclosure Deflagration (Event 8) .............................................................................15 3.3.3 Loss of Confinement/Containment ..........................................................................15 Vehicle/Equipment Impacts Waste/Waste Containers (Event 9) ..............................15 Drop/Impact/Spill Due to Improperly Handled Container, etc. (Event 10) .............16 Collapse of Stacked Containers (Event 11) ..............................................................16 Waste Container Over-Pressurization (Event 12) .....................................................16 3.3.4 Direct Exposure to Radiation Events (Event 13) .....................................................16 3.3.5 Criticality Events (Event 14) ....................................................................................16 3.3.6 Externally Initiated Events .......................................................................................16 DOE-STD-5506-2021 iii Aircraft Impact with Fire (Event 15) ........................................................................16 External Vehicle Accident (Event 16) ......................................................................17 External Vehicle Accident with Fire (Combustible or Pool) (Event 17) ..................17 External Explosion (Event 18) .................................................................................17 External Fire (Event 19) ...........................................................................................17

3.3.7 Natural Phenomenon Hazard Initiated Events .........................................................17 Lightning (Event 20) ................................................................................................17 High Wind (Event 21) ..............................................................................................18 Tornado (Event 22) ...................................................................................................18 Snow/Ice/Volcanic Ash Build-up (Event 23) ...........................................................18 Seismic Event (Impact Only) (Event 24) .................................................................18 Seismic Event with Fire (Event 25) .........................................................................18 Flood Event (Event 26) ............................................................................................18 3.3.8 Chemical Initiated Events (Event 27) ......................................................................18 3.4 Expected Operational Events ..................................................................................................20 TRU Waste Source Term Analysis ......................................................................................22 4.1 Purpose ...................................................................................................................................22 4.2 Material-at-Risk ......................................................................................................................22 4.2.1 Data Uncertainties in Hazard and Accident Analysis ...............................................22 4.2.2 Defining a Bounding MAR for TRU Operations .....................................................23 4.3 Damage Ratios ........................................................................................................................26 4.3.1 Container Integrity ...................................................................................................28 4.3.2 Container Deflagration Events .................................................................................32 4.3.3 Fire Scenario Damage Ratios for TRU Waste Containers .......................................38 Drums Exposed by Flammable/Combustible Liquid Pool Fires ..............................39 Drums Exposed by Ordinary Combustible Fires .....................................................49 Fire Damage Ratios for Other Containers ................................................................50 4.3.4 Damage Ratios for Mechanical Insults ....................................................................53 4.3.5 Natural Phenomena Damage Ratios for TRU Waste Container Storage ......................................................................................................................62 4.4 Airborne Release Fractions/Respirable Fractions ..................................................................67 4.4.1 Deflagration and Overpressure Events .....................................................................68 4.4.2 Fire Scenarios ...........................................................................................................74 4.4.3 Mechanical Insults ....................................................................................................75 Low-Energy Mechanical Insults ..............................................................................75 High-Energy Mechanical Insults ..............................................................................77

4.5 Chemical Reaction Source Term ............................................................................................79 4.6 Consequence Analysis ............................................................................................................81 DOE-STD-5506-2021 iv TRU Waste Hazard Controls Selection and Standardization ..........................................83 5.1 Purpose ...................................................................................................................................83 5.2 TRU Waste Controls ...............................................................................................................83 5.2.1 TRU Waste MAR Effects on Control Selection .......................................................85 References ..............................................................................................................................97 Understanding and Using the MAR Algorithms .......................................... A-1 Fully Characterized MAR Algorithm .................................................................................. A-1 Limited Characterization MAR Algorithm .......................................................................... A-2 References for APPENDIX A .............................................................................................. A-7 Container Deflagrations ...................................................................................B-1 Introduction ...........................................................................................................................B-1 Hydrogen Measurements in TRU Waste Drums ....................................................B-4 Hydrogen Measurements in Drums from Culverts at SRS ....................................B-5 Review and Evaluation of Pertinent Experiments and Literature of Internal Deflagration in TRU Waste Containers .............................................................................. B-11 Idaho Drum H2 Explosion Tests ........................................................................... B-11 SRS Drum H2 Explosion Tests .............................................................................B-17 Burning of Ejected Wastes ...................................................................................B-19 Volatile Organic Compounds ...............................................................................B-22 Hydrogen Combustion and Deflagration-to-Detonation Transition (DDT) ...................................................................................................................B-26 B.2.5.1 Electric Power Research Institute (EPRI) Hydrogen Tests ..................................B-27 B.2.5.2 Sandia Hydrogen Tests .........................................................................................B-30 B.2.5.3 Rockwell Atomics International (AI) Hydrogen Tests .........................................B-33 B.2.5.4 ARROW-PAK™ DDT Test ...................................................................................B-36 B.2.5.5 Drum DDT Position Paper ...................................................................................B-37 Container Response to Internal Pressures ............................................................B-38 Drum Response to External Pressures .................................................................B-43 Other Waste-Container Considerations ................................................................B-45

B.2.8.1 Idaho Testing of Boxes and Bins ..........................................................................B-47 Deflagration Testing for CH Payload Containers and Filter Vents at Southwest Research Institute ...............................................................................B-48 Summary and Recommendations for Deflagration Release Parameters ............................B-51 Assumptions .........................................................................................................B-51 Material-at-Risk ...................................................................................................B-52 Damage Ratio .......................................................................................................B-52 Airborne Release Fraction and Respirable Fractions ...........................................B-53 DOE-STD-5506-2021 v Overall Composite Release Fraction ....................................................................B-54 References for APPENDIX B .............................................................................................B-54 Damage Ratios for Container Insults and Fires ........................................... C-1 Fire Scenarios Damage Ratios for TRU Waste Container ....................................................C-2 Waste Container Fire Testing Insights ....................................................................C-3 Lid Loss and Ejection Fraction ............................................................................C-10 Seal Failures .........................................................................................................C-12 Pipe Overpack Container, Type 7A Drum, and Criticality Control Overpack Fire Testing ..........................................................................................C-18 C.1.4.1 Initial Pipe Overpack Container Fire Testing .......................................................C-18 C.1.4.2 Additional Pipe Overpack Container, Type 7A Drum, and Criticality Control Overpack Fire Testing .............................................................................C-19 C.1.4.3 Criticality Control Overpack Testing ...................................................................C-22 Mechanical Insults (Low- and High-Energy) .....................................................................C-24 Container Test Results ..........................................................................................C-25 C.2.1.1 Drum Drop Tests ..................................................................................................C-25 C.2.1.2 Pallet Tests ............................................................................................................C-27 C.2.1.3 Welded-Metal Waste Box Tests ............................................................................C-29 C.2.1.4 Pipe Overpack Container Testing for Accidents Other Than Fires ......................C-30 Impact and Drop Accidents ..................................................................................C-34 C.2.2.1 Single Container Drops ........................................................................................C-34 C.2.2.2 Palletized Drum Falls ...........................................................................................C-37 C.2.2.3 Waste Container Puncture by Forklift ..................................................................C-40 C.2.2.4 Compressed-Gas-Cylinder-Missile Impact ..........................................................C-42 C.2.2.5 Damage Ratio Summary for Accidents ................................................................C-44

References for APPENDIX C .............................................................................................C-44 Criteria for TRU Waste Drums Requiring Venting/Purging Due to Elevated Internal Hydrogen Concentrations .................................................................. D-1 Executive Summary .................................................................................................................. D-1 Introduction .......................................................................................................................... D-1 Purpose ................................................................................................................................ D-3 Criteria ................................................................................................................................. D-3 Definitions ........................................................................................................................... D-3 TRU Waste ........................................................................................................................... D-4 55-Gallon DOT, Metal Drums ............................................................................... D-4 Types of Waste ...................................................................................................... D-5 Hydrogen from TRU Wastes ............................................................................................... D-6 DOE-STD-5506-2021 vi Hydrogen Gas Properties ...................................................................................... D-6 Hydrogen Gas Combustion Phenomenon ............................................................. D-7 Combustion of Hydrogen–Air Mixtures ............................................................... D-7 Hydrogen Gas Combustion Properties .................................................................. D-8 Hydrogen Concentrations in TRU Waste Drums .................................................. D-8 Literature Data on Burning of Hydrogen–Air Mixtures ...................................................... D-9 AI 1973 .................................................................................................................. D-9 D.7.1.1 Detonation Tests .................................................................................................. D-11 D.7.1.2 Flame Tests .......................................................................................................... D-13 EPRI 1988 ........................................................................................................... D-14 D.7.2.1 Combustion in Premixed Hydrogen–Air–Steam Atmospheres ........................... D-17 D.7.2.2 Pre-Mixed Combustion Phenomenon ................................................................. D-17 D.7.2.3 Effect of Scale ..................................................................................................... D-18 D.7.2.4 Effect of Hydrogen and Steam Concentrations ................................................... D-18 SNL 1989 (Note: Complete document was not available for review.) ................ D-18 D.7.3.1 Abstract ............................................................................................................... D-18 D.7.3.2 Conclusions from Tests ....................................................................................... D-20 D.7.3.3 Adiabatic Isochoric (Constant Volume) Complete Combustion (AICC)

Pressure ............................................................................................................... D-20 D.7.3.4 Flammability Limits ............................................................................................ D-20 D.7.3.5 Ordinary Turbulent Deflagration ......................................................................... D-21 D.7.3.6 Flame Acceleration — Highly Accelerated Deflagration ................................... D-21 D.7.3.7 Deflagration-to-Detonation Transition ................................................................ D-21 D.7.3.8 Experimental Results ........................................................................................... D-23 LANL July 2002 .................................................................................................. D-24 EG&G 1983 (Experimental Studies of H2 Explosions in TRU Waste Drum) .......................................................................................... D-25 WSRC-TR-90-165 .............................................................................................. D-30 D.7.6.1 Pressure Vessel Tests ........................................................................................... D-30 D.7.6.2 Drum Mixing Tests .............................................................................................. D-31 D.7.6.3 Drum Explosion Test ........................................................................................... D-31 D.7.6.4 Results ................................................................................................................. D-31 WSMS 2006 (DDT) ............................................................................................ D-32 D.7.7.1 Introduction ......................................................................................................... D-33 D.7.7.2 Technical Position ............................................................................................... D-33 D.7.7.3 Literature Review ................................................................................................ D-34 EMRTC 2004 (DDT) .......................................................................................... D-35 WSRC 2007 ......................................................................................................... D-35 Summary and Conclusions ................................................................................................ D-36 DOE-STD-5506-2021 vii References .......................................................................................................................... D-37 Energetic Chemical Events ..............................................................................E-1 Introduction ........................................................................................................................... E-1 WIPP Event ............................................................................................................ E-1 INL ARP V Event ................................................................................................... E-3 Radiological Source Term Evaluations of WIPP and INL Events ........................................ E-5 Modeling Energetic Release Parameters .............................................................................. E-8 Radiological Source-Term Evaluations of a Drum Over- pressurization Event ............................................................................................... E-9

References for APPENDIX E ............................................................................................. E-10 DOE-STD-5506-2021 viii Figures Figure Page Figure 4-1. Example Graphic Assessment of Pool Fire Damage.................................................. 45 Figure 4-2. Fire Damage Ratios (DRs) for Direct-Loaded Drums ............................................... 48 Figure 4-3. Comparison of Drum DR and ARF×RF for Contaminated Solids in Drops, Falls, and Vehicle Crashes ................................................................................................. 60 Figure 4-4. Example Graphic 20 mph Vehicle Crash with Follow-On Pool Fire ......................... 62 Figure C-1. Geometries for Determining Critical Incident Flux .............................................. C-14 Figure C-2. Comparison of Critical Incident Flux Criteria ....................................................... C-15 DOE-STD-5506-2021 ix Tables Table Page Table 3-1. Hazard Sources and Potential Events ............................................................................ 9 Table 3-2. Minimum TRU Waste Activity / Hazard Evaluation Event Matrix 1 ...........................11 Table 4-1. Bounding MAR Approach for TRU Waste Operations ............................................... 25 Table 4-2. Payload Container Integrity Checklist ......................................................................... 31 Table 4-3. Drum Deflagration Fractions of MAR ........................................................................ 34 Table 4-4. Critical Flux Criteria Required to Obtain Seal Failure ................................................ 42 Table 4-5. Container Drop and Impact Damage Ratios ................................................................ 57 Table 4-6. Vehicle Crash Damage Ratios ...................................................................................... 58 Table 4-7. Damage Ratios for Containers Impacted by Seismic Debris ....................................... 66 Table 4-8. ARF×RF Value Applicable to TRU Waste Accidents .................................................. 67 Table 5-1. Hazard Controls ........................................................................................................... 88 Table A-1. Order of Statistic (Container “r”) for a Given Waste Container Population ........................................................................................................................................A-4 Table A-2. Z-Score Values for Various Confidence Intervals ..................................................... A-6 Table B-1. Fraction of Stored TRU Waste Drums Containing Flammable Hydrogen Concentrations ............................................................................................................B-4 Table B-2. Unvented Culvert Drum Initial Headspace Gas Results ............................................B-6 Table B-3. Fraction of Culvert Drums Capable of Complete Combustion with > 5- vol% O2 and at Least 50% of the Corresponding H2 Concentration ...........................................B-7

Table B-4. Drum H2 Concentration > 15.0 vol% (> 14.65 vol% with Uncertainty), 39 Drums ...................................................................................................................................... B-7 Table B-5. Drum H2 Concentration Between 8 and 15 vol% (7.28–13.65 vol% with Uncertainty), 24 Drums ........................................................................................................ B-9 Table B-6. Drum H2 Concentration Between 4 and 8 vol% (3.64–7.28 vol% with Uncertainty), 22 Drums ..............................................................................................................B-10 Table B-7. Purpose and Initial Conditions for Each Test .......................................................... B-12 Table B-8. Idaho Drum Deflagration Tests Result .................................................................... B-13 Table B-9. Pressure Vessel Test Data ........................................................................................ B-18 Table B-10. Drum Explosion Data .............................................................................................B-19 DOE-STD-5506-2021 x Table B-11. Description of Combustibles Loaded into Drums ................................................. B-23 Table B-12. Summary of Mass Loss .............................................................................................B-25 Table B-13. EPRI Test Conditions and Results ........................................................................ B-28 Table B-14. Summary of the Test Parameters and Some Test Results ..................................... B-31 Table B-15. Detonation Test Results ......................................................................................... B-34 Table B-16. Flame Tests Data Summary .................................................................................. B-35 Table B-17. Drum Capacities, Specifications, and Tests Conducted ........................................ B-39 Table B-18. INL Pneumatic Testing of 55-Gallon Drums ........................................................ B-42 Table B-19. Deflagration Test Results ...................................................................................... B-49 Table B-20. Overall Drum Composite Release Fraction .......................................................... B-54 Table C-1. Summary of Key Pool Fire Equations ...................................................................... C-3 Table D-1. Properties of Gaseous Hydrogen (H2) (After LANL 2002) ...................................... D-6 Table D-2. Hydrogen Gas Combustion Properties ..................................................................... D-8 Table D-3. Fraction of Stored TRU Waste Drums Containing Flammable Hydrogen Concentrations (from HNF-19492) ............................................................................ D-9 Table D-4. Detonation Test Summary (After AI 1973)............................................................. D-11 Table D-5. Flame Test Data Summary ...................................................................................... D-13 Table D-6. Test Conditions (EPRI 1988) .................................................................................. D-15 Table D-7. Summary of the Test Parameters and Some Test Results (SNL 1989) ................... D-23 Table D-8. Purpose and Initial Conditions for Each Test (EG&G 1983).................................. D-27

Table D-9. Gas Generation Tests Performed at the INEL Building FY-82 (EG&G 1983) ......................................................................................................................................... D-28 Table D-10. Pressure Vessel Test Data (WSRC-TR-90-165) .................................................... D-31 DOE-STD-5506-2021 1 Introduction 1.1 Background The DOE is responsible for the safe handling, packaging and ultimate disposal of transuranic (TRU) wastes at the Waste Isolation Pilot Plant (WIPP) located near Carlsbad, New Mexico. Much of this waste, which is a result of operations supporting the U.S. nuclear weapons mission, is now stored at numerous DOE sites located across the United States. These wastes can present significant hazards to workers, the environment, and the public if not adequately controlled. While numerous and located within multiple states, facility operations supporting the TRU waste management mission have shared similarities in terms of the hazards and scope of operations. However, facilities often employ a variety of different controls to manage the TRU wastes. Recognition of these inconsistencies led the DOE to develop this technical Standard, which lays out expectations for analyzing and controlling TRU waste hazards. To support this effort, DOE had to overcome several challenges. Chief among them was that TRU wastes are present at both large and small sites and involve wastes ranging from very low radioactive levels to those with significant radiological hazards. A one-size-fits-all approach could be overly expensive and not necessarily in line with relative lower risks. A second challenge was that TRU waste operations are conducted in a variety of newly designed structures and existing buildings originally intended for other DOE missions. These older facilities may not meet current facility design requirements, although they may be compliant with their original design criteria (e.g., “code of record”). Therefore, it was recognized that protective features designed into existing facilities are not always reliable or available as in new facilities. Often, alternative controls such as Specific Administrative Controls per DOE-STD-1186-2016, Specific Administrative Controls, may become the primary controls available. [NOTE: This does not relieve a new facility or major facility modification from DOE Order O 420.1C, Facility Safety, nuclear facility requirements.] To support these strategies, DOE collected hazard analysis and control data from all of its major TRU waste sites. This information was used to provide a baseline against which analytical methods and proposed controls could be evaluated, compared, and selected. It also highlighted inconsistencies among TRU waste sites that warranted further guidance. The technical bases for some of the hazard and accident analysis parameters recommended in this document are based on: (1) previously published DOE recommended safety analysis practices (2) extrapolation of experimental data from waste container testing and analytical analyses; or (3) precedents established in the DOE Complex during the development and approval of existing TRU waste facility DSAs. 1.2 Scope Based on the evaluation of existing Safety Basis information and input received from TRU waste operations personnel, analysts and DOE Safety Basis reviewers, the Standard focuses on topics related to hazard and accident analysis and hazard controls. These topics are addressed in a level of detail that supports the existing framework of nuclear facility Safety Basis requirements and standards.

DOE-STD-5506-2021 2 Specific topical areas covered in the Standard, and their associated sections are as follows: • Section 2, Acronyms, provides definitions to all acronyms used in the Standard. • Section 3, Identification and Evaluation of TRU Waste Events, discusses the types of hazards expected during TRU waste operations, defines a minimum set of accidents to be evaluated in the DSA, and addresses DSA provisions for addressing incidents that are inherent to normal operations such that operational impacts from their occurrence are appropriately minimized. • Section 4, TRU Waste Source Term Analysis, defines analytical methods and assumptions related to unmitigated analysis, Material-at-Risk, Damage Ratios, and Airborne Release Fractions/Respirable Fractions. • Section 5, TRU Waste Hazard Controls Selection and Standardization, provides guidelines for standardizing the hazard control selection process and gives specific controls that are appropriate for TRU waste operations. • Section 6, References, provides a list of all references cited in the main body of the Standard. Additional references are provided within each appendix. • APPENDIX A, Understanding and Using the MAR Algorithms, provides discussion of the statistical approach for determining Material-at-Risk (MAR) and for how to calculate values for the approach described in Section 4.2.2 of the Standard. • APPENDIX B, Container Deflagrations, provides the technical basis for Damage Ratios presented in the Standard for deflagration events. • APPENDIX C, Damage Ratios for Container Insults and Fires, provides technical justifications supporting Damage Ratios presented in the Standard for fires and mechanical insult events. • APPENDIX D, Criteria for TRU Waste Drums Requiring Venting/Purging Due to Elevated Internal Hydrogen Concentrations, provides a basis for drum lid loss due to deflagrations in 55-gallon drums. • APPENDIX E, Energetic Chemical Events, provides guidance for the unmitigated consequence analysis of potential energetic events from chemical reactions associated with TRU waste drums. 1.3 Purpose This Standard provides detailed guidance for consistently analyzing hazards and selecting controls for TRU waste activities. The hazards analysis, accident analysis, and controls for TRU waste activities shall be integrated into the overall Safety Basis documents for DOE Category 1, 2, or 3 nuclear facilities prepared in accordance with 10 CFR Part 830 (Nuclear Safety Management), Subpart B requirements (or alternate methodology where approved in accordance with the regulation). 1.4 Applicability The information contained in this Standard is intended for use by all DOE and National Nuclear Security Administration (NNSA) sites and all contractors for DOE- or NNSA-owned or -leased, Hazard Category 1, 2, or 3 nuclear facilities or nuclear operations that involve retrieval, generation, handling, storage, and processing (e.g., glovebox or hotcell operations) involving TRU or low-level waste. This Standard applies 3 DOE-STD-5506-2021 to Documented Safety Analyses (DSAs) complying with “safe harbor methods” in Table 2 to Appendix A of 10 CFR Part 830, Subpart B (or alternate methodology where approved in accordance with the regulation) and the associated Technical Safety Requirements (TSRs).

This Standard is not a safe harbor methodology as set forth in Appendix A to 10 CFR Part 830, Subpart B. Nothing in this Standard is intended to conflict with or modify the requirements for compliance with safe harbor methodologies listed in 10 CFR Part 830. In addition, the Standard is not intended to conflict with requirements of 10 CFR Part 830.206 related to new Hazard Category 1, 2, or 3 nuclear facilities or major modifications. In the case of an apparent conflict between this Standard and a 10 CFR Part 830, Subpart B requirements, as well as supporting “safe harbor” methodologies in Table 2 of Appendix A of 10 CFR Part 830, Subpart B, the language in the “safe harbor” method takes precedence, unless approval for an alternative methodology is requested and approved per the current DOE approval process for 10 CFR 830 exemptions or interpretations. DOE Standard 5506 is intended to supplement safe harbor methodologies, such as DOE-STD-3009-2014 (Preparation of Nonreactor Nuclear Facility Documented Safety Analysis) or DOE-STD-3011-2016 (or previous versions for existing facilities), and provides specific information pertinent to facilities that handle, store, or process transuranic waste. The process used to justify deviations from methods prescribed in the Standard should not be confused with the process used for exemptions from DOE nuclear safety requirements. In the former case, technical justifications for analytical methods or key assumptions are developed and submitted to the DOE Safety Basis Approval Authority for their approval of deviation from this Standard. Such deviations should be documented in the Safety Evaluation Report. Deviations should not be used for safety controls that are needed to comply with nuclear safety design criteria of DOE Order 420.1C (i.e., a new facility or major modification). Where controls cannot meet current requirements, exemptions with appropriate compensatory measures are generally needed to authorize acceptability of not meeting the requirement. Depending on the requirement and its applicability to existing facilities, the Safety Basis DOE Approval Authority may not be the same person as the DOE authority for an exemption to current DOE Orders or other requirements. Furthermore, approval of exemptions to DOE Order requirements involving nuclear safety need concurrence of the DOE and/or NNSA Central Technical Authorities per the DOE exemption process in effect at the time of the request. 1.5 Use of the Words Shall and Should The verbs “shall” and “should” are used throughout this Standard. The word “shall” denotes actions that are required to satisfy this Standard. The word “should” is used to indicate recommended practices. The use of “may” with reference to application of a procedure or method indicates that the use of the procedure or method is optional. 1.6 Overview of Changes in this Revision This revision of DOE-STD-5506-2007, Preparation of Safety Basis Documents for Transuranic (TRU) Waste Facilities, incorporates experience and lessons learned from the DOE complex. It also updates the basis for source-term recommendations to reflect the latest available container testing and evaluation of DOE-STD-5506-2021 4 available data. Previous DSA guidance was deleted from this Standard that is now adequately addressed in DOE-STD-3009-2014 and DOE-HDBK-1224-2018, Hazard and Accident Analysis Handbook.

DSAs that were prepared in accordance with DOE-STD-5506-2007 should evaluate the changes in this revision and determine whether a DSA update is needed. In particular, the following changes should be evaluated: • Applicability of the newly added “Chemical Initiated Releases” event in Section 3.3, TRU Waste Operations Minimum Set of Accidents, as well as related source term guidance in Section 4.5, Chemical Reaction Source Term, and APPENDIX E, Energetic Chemical Events; • Clarifications in the renumbered Section 4.2.2, Defining a Bounding MAR for TRU Operations, that includes corrections of typographical errors in Table 4-1, “Bounding MAR Approach for TRU waste operations,” new guidance for addressing statistical anomalies as described in Footnote 4, and additional conditions for when a statistical approach is appropriate for determining MAR; • Updates to values and additional bases provided for the use of various source term factors in Section 4.3, Damage Ratios, and Section 4.4, Airborne Release Fractions/Respirable Fractions. • Updates and clarifications of several safety controls described in Section 5.2, TRU Waste Controls. DSAs should be updated if conclusions of the hazard and accident analysis are no longer conservative or if new controls may be needed. The decision for updating the DSA to this revised Standard will be made by the DOE or NNSA program office and Safety Basis Approval Authority. DOE-STD-5506-2021 5 Acronyms AA accident analysis AI (Rockwell) Atomics International AIB (DOE) Accident Investigation Board AICC adiabatic isochoric (constant volume) complete combustion AK acceptable knowledge ANSI American National Standards Institute ARF airborne release fraction ARP Accelerated Retrieval Project BoK Basis of Knowledge Document CCC criticality control container CCE chemical compatibility evaluation CCO criticality control overpack CFR Code of Federal Regulations CH contact-handled CVS confinement ventilation system DBE Design basis earthquake DNFSB Defense Nuclear Facilities Safety Board DOE U.S. Department of Energy DOT U.S. Department of Transportation DR damage ratio DSA documented safety analysis DU depleted uranium DVS drum venting system ED energy density EM (DOE Office of) Environmental Management EPA Environmental Protection Agency FRP fiberglass reinforced plywood (box) FSS fire suppression system L/D length/diameter (ratio) LANL Los Alamos National Laboratory LCO limiting conditions for operations LFL lower flammability limit LLNL Lawrence Livermore National Laboratory LPF leak-path factor MAR material-at-risk DOE-STD-5506-2021 6 MOI maximally exposed offsite individual NCSE nuclear criticality safety evaluation NDA non-destructive assay NDE non-destructive examination NFPA National Fire Protection Association NNSA National Nuclear Security Administration NPH natural phenomena hazards OSHA U. S. Occupational Safety and Health Administration PC pipe component PE-Ci plutonium equivalent curies PISA potential inadequacy of the documented safety analysis PMMA polymethyl methacrylate PNNL Pacific Northwest National Laboratory POC pipe overpack container RF respirable fraction RH remote-handled RLC removable lid canister SAC specific administrative controls SC Safety Class SIH standard industrial hazard SFPE Society of Fire Protection Engineers SLB2 standard large box 2 SME subject matter expert SMP safety management program SRS Savannah River Site SSC structures, systems, and components ST source term SWB standard waste box TBD to be determined TDOP ten drum overpack TED total effective dose TI tolerance interval TRU transuranic TSR technical safety requirements UCL upper confidence limit USQ unreviewed safety question UTL upper tolerance limit

DOE-STD-5506-2021 7 VOC volatile organic compound WAC waste acceptance criteria WIPP Waste Isolation Pilot Plant DOE-STD-5506-2021 8 Identification and Evaluation of TRU Waste Events 3.1 Purpose This section provides guidance on identification of hazards expected during various types of TRU waste operations, as well as a minimum set of accident events that are applicable based on these hazards. The definition of Standard Industrial Hazards (SIH), as discussed in DOE-STD-3009-2014, is also clarified to help distinguish those hazards that do not require analysis within the DSA. Finally, this section provides a distinction for certain operational events that are to be expected during the course of normal TRU waste operations. 3.2 Hazard Identification and Standard Industrial Hazard Screening The identification of hazards inherent in TRU waste activities is necessary to provide a sound basis for identifying potential accident events and performing a hazard evaluation. The hazard identification process results in a comprehensive list of hazardous materials and energy sources that are present in the facility or operation. This process shall be conducted in accordance with the DOE-STD-3009-2014, or applicable safe-harbor standard, for hazard identification and selection of accidents. Hazards commonly expected for TRU waste operations are identified in Table 3-1, Hazard Sources and Potential Events. This listing provides major hazard sources and material groups that could be potential initiators for specific accident events discussed in Section 3.3. Where these hazards are present in a given TRU waste operation, analysts shall evaluate the applicability of the corresponding accident event(s). Hazards identified in Table 3-1 do not always result in accidental release of radiological materials or hazardous chemicals and/or high direct radiation exposures (i.e., as required to be evaluated in the DSA). Depending on the location and specific characteristics of the hazard, it may be considered an SIH. DOE- STD-3009-2014 defines an SIH as a hazard that is “routinely encountered in general industry and construction.” Further, these hazards: ... are addressed by provisions of 10 C.F.R. 851, Worker Safety and Health Program, which requires identification and assessment of worker hazards and compliance with safety and health standards that provide specific safe practices and controls. Examples of SIH types that are common to TRU waste operations include radiography equipment that is governed by American National Standard Institute (ANSI) standards and heavy equipment hazards regulated by the U.S. Occupational Safety and Health Administration (OSHA). It is not the intention of the DSA to provide analysis of SIH type of hazards that are adequately controlled in accordance with 10 CFR 851 (Worker Safety and Health Program) or evaluate releases of hazardous chemicals, when such chemicals are determined to be adequately managed by a hazardous material protection program. These hazards are analyzed as part of the hazard scenario in a DSA only if they can be an event initiator (for example, 115-volt wiring as initiator of a fire), a contributor to a significant uncontrolled release of radioactive or other hazardous material, result from chemical or radiological 9 DOE-STD-5506-2021 hazards (for example, when an explosion is caused by radiolysis inside a tank), or are considered a unique-facility worker hazard.

Application of a hazard screening occurs during the hazard identification process and can be helpful in distinguishing those hazards that are evaluated in the DSA. DOE-STD-3009-2014, Section A.1, “Standard Industrial Hazards” provides guidance for the requirements of Section 3.1.1, “Hazard Identification;” Section A.2, “Chemical Hazards” provides guidance for the requirements of Section 3.1.3.3, “Chemical Hazards.” For Hazard Category 3 facilities, DOE-STD-1228-2019, Preparation of Documented Safety Analysis for Hazard Category 3 DOE Nuclear Facilities, Section A.2.3, “Chemical Hazard Screening” provides additional discussion and should be used as the basis for screening of standard industrial hazards and chemical hazards and screening criteria. DOE-HDBK-1224-2018, Section 2.2.4, “Exclusion of Standard Industrial Hazards and Other Hazardous Materials” also provides additional discussion and should be used as the basis for screening standard industrial hazards and hazardous chemicals. Table 3-1. Hazard Sources and Potential Events DOE-STD-5506-2021 10 3.3 TRU Waste Operations Minimum Set of Accidents The following section represents the minimum set of accident events that shall be addressed in the DSA hazard evaluation when the hazard identification indicates the presence of potential initiators that could lead to the accident event. If a particular event is not applicable for a facility—e.g., volcanic ash does not apply to many DOE locations—then the basis for excluding the event should be developed and documented within the DSA hazard evaluation. The applicability of a specific accident also depends on whether it is plausible during the TRU waste activity being conducted; e.g., a vehicle accident may not be plausible during glovebox repackaging activities. The following example list of general TRU waste activities has been developed to facilitate an understanding and characterization of TRU waste accident events: • Characterization. Non-Destructive Assay (NDA), Non-destructive Evaluation (NDE), and Headspace Gas Sampling (HGS). These activities are those typically required for package acceptance and certification at WIPP. In some cases, gas generation testing (e.g., CH-TRAMPAC, Section 5.2.5) may also be performed. • Container Handling. Lifting and moving TRU waste containers with forklifts, cranes, drum handlers, etc.; stacking; banding; loading and unloading from waste container arrays; overpacking; and loading onto a transport vehicle until ready for transport. • Venting and/or Abating/Purging. Installing vents to release flammable gases built up within the TRU waste container, allowing gases to passively vent, and purging the TRU waste container headspace. The purpose of these activities is to reduce the potential flammable gas concentration within the TRU waste container to a level at which a deflagration hazard doesn’t exist. • Staging and Storage. Static conditions which may include staging (temporary storage), storage, surveillance, and maintenance. Staging and storage may take place inside a facility with features such as fire suppression and ventilation; inside temporary structures, such as tents that only protect the waste container from the elements; or outside of any physical structure. • Retrieval and Excavation. Excavation of buried waste and/or retrieval from original storage location. DOE-STD-5506-2021 11

• Waste Repackaging. Intrusive material handling. May include sorting, visual inspection of waste, size reduction, compaction, invasive sampling, dewatering, repackaging, consolidation, conditioning or treatment of reactive material, and absorption or solidification of liquids. • Type B Container Loading/Unloading. Handling and storage/staging of Type B containers. The minimum set of accident events presented in this section addresses those events with the potential for consequences that could be significant enough to warrant explicit technical safety requirements (see additional discussion in Section 5). A matrix of the minimum accident events versus typical TRU waste activities discussed above is provided in Table 3-2, Minimum TRU Waste Activity / Hazard Evaluation Event Matrix. Areas of the table marked by “X’s” indicate potential applicability. Accident events are presented according to broad categories that include fires, explosion events, loss of confinement/containment, direct radiation exposure, criticality, externally initiated events, and natural phenomena events. These events are applicable to both Contact-Handled (CH) and Remote-Handled (RH) TRU waste activities. The descriptions and causes of accidents may not be inclusive of certain hazards or operations that are unique to a given site. The hazard identification process, conducted in accordance with DOE-STD-3009-2014 (or applicable safe-harbor standard) should identify those hazards not addressed by this Standard (DOE-STD-5506-2021). When an accident is applicable based on the facility’s hazard identification and the type of TRU waste activity being conducted, the accident shall be covered in the DSA hazard evaluation. A subset of these accidents may also require formal accident analysis where required in accordance with DOE-STD-3009- 2014 (or applicable safe-harbor standard). Table 3-2. Minimum TRU Waste Activity / Hazard Evaluation Event Matrix 1 DOE-STD-5506-2021 12 3.3.1 Fire Events The fire events provided below should be consistent with the conclusions of a facility’s fire hazard analysis (FHA). Fire sizes and types are generally defined below to facilitate the selection of controls in Section 5. In addition, the use of the term “facility” within the fire events does not necessarily mean the evidence of a structure—i.e., fires may occur inside or outside of a structure. Fuel Pool Fires (Event 1) The analysis of liquid-fuel fires, separate from other fires, is important because liquid fuel has the potential to result in pool fires that have a substantially higher source term than combustible-material fires when TRU waste containers are involved in the event. Pool fires can cause rapid heating of containers. This heating can cause relatively small containers, such as 55-gallon drums, to experience rapid pressure buildup, resulting in a lid failure and expulsion/ejection of material from the container. 13 DOE-STD-5506-2021 These potential fires are associated with the ignition of pools by various ignition sources, such as thermal energy from the equipment or sparks from moving containers. The fuel pool is formed from the leaking of equipment and/or vehicle flammable/combustible liquids or the spilling of the liquids during refueling, maintenance, or an impact from equipment/vehicles used to support TRU waste operations. The potential amount of fuel is dependent on the equipment/vehicles used within the facility footprint and may range from a few gallons to thousands of gallons. Separate fuel pool fire events should be included, as necessary, for complete hazard evaluation and control selection.

Additionally, if the fuel pool fire event is initiated by an equipment/vehicle impact and postulated to impact uncontainerized and/or containerized waste (See Event 9), an additional event that addresses the hazards of both the fuel pool fire and the vehicle impact shall be analyzed for complete hazard evaluation and control selection. Small Fire (Event 2) Small fires may affect either one container during a container fire or one to several containers through exposure or direct impingement, but outside of any facility confinement enclosure (e.g., a glovebox). This type of fire is limited in size and is contained within a fire-limited area (as defined in the facility Fire Hazards Analysis) . Additionally, the intensity of a small fire may be inadequate to result in automatic Fire Suppression System (FSS) activation. These fires, in general, will cause material in containers to burn as confined material. However, some containers (e.g., those with relatively significant quantities of liquids or reactive materials) may result in drum pressurization, lid failure, and ejection of some of the container contents. The ejected material would burn as unconfined material, resulting in a greater release than confined material. The event covers all small fires initiated within the facility but outside of any facility enclosures. This fire is started from the ignition of combustible and/or flammable materials within the facility as well as exposure fires from vehicles or other equipment within the facility. Fires of this type affect containers through exposure or direct impingement. Separate small-fire events from hazards associated with various facility activities may be required to ensure a complete hazard evaluation. The propagation of these fires into a larger fire is addressed in a separate event (Event 4). Enclosure Fire (Event 3) For facilities using enclosures such as gloveboxes or hot cells, this fire is addressed separately from other small-fire events to ensure a complete hazard evaluation. This fire covers all internally initiated fires. The ignition source may be from pyrophoric or spontaneous combustion reaction, chemical reaction, or other source of internal heat generation. Flammable gas inside the enclosure may also result in a deflagration, which is addressed in a separate event. Additionally, if waste treatment activities not typically associated with TRU waste operations are conducted within an enclosure (e.g., stabilization of pyrophoric material through controlled oxidation), separate events may be required for complete hazard evaluation and control selection. Large Fire (Event 4) This is a fire that propagates from any of the proposed smaller fire events. Propagated fires of different sizes may be proposed; the size will depend on the facility configuration. For example, a large, multilevel facility may have a room fire, a level fire, and a full-facility fire. The size of the fire analyzed within the 14 DOE-STD-5506-2021 DSA will depend on assumptions addressed in the FHA. For example, a full facility fire may not be plausible because of noncombustible facility construction/design and lack of operational needs for combustible/flammable materials (i.e., combustible loading is inherently low by the nature of the activity without the need to rely on credited controls to maintain that condition). Note, however, that if passive structures, systems or components (SSCs), such as fire-rated concrete walls, are assumed to prevent propagation of fire from one facility TRU waste container area to another, such SSCs typically need to be protected as TSR design features.

3.3.2 Explosion Events These events can be linked to causes such as radiolysis and generation of hydrogen or waste constituents generating volatile organic compounds. Chemical reactions within the waste stream, as discussed in Event 27, can also initiate events discussed in this section. Ignition of Fumes Results in an Explosion (external to container) (Event 5) This event is caused by hazards external to the waste matrix, such as vehicle fuel/fumes, battery explosions, welding gases, or other explosive gases used in the facility. In addition to explosion overpressures, an explosion could produce missiles that could impact containers of waste or facility SSCs. For waste in containers, the release mechanism would essentially be an impact. Waste Container Deflagration (Event 6) This event is due to hydrogen or other flammable/explosive gases or vapors (e.g., off-gas from Volatile Organic Compounds [VOCs]) inside the container) in a suspect container. A suspect container is one that has no vent; a plugged vent1; or an inadequate vent (e.g., flammable gas generation rate greater than venting capability); and meets at least one of the following criteria: Obvious indications of pressurization; Waste stream characteristics indicate a potential for generating concentrations of hydrogen greater than 8% by volume; Waste stream characteristics indicate a potential for generating concentrations of other flammable gas mixtures greater than or equal to the Lower Flammability Limit (LFL); or Waste stream data is either inadequate or unavailable to rule out the potential for generating concentrations of hydrogen greater than 8% by volume or other flammable gas mixtures greater than or equal to the LFL. Application of these criteria will typically result in the need to analyze a deflagration at most TRU waste facilities, as data may be unavailable to rule out the potential for generating hydrogen concentrations greater than 8% by volume. A technical basis for ruling out the potential for rapid gas generation and high hydrogen concentrations within a container could include actual headspace gas sampling data, comparison to decay heat limits, or consideration of the form/composition of waste. 1 A plugged vent does not include temporary covering or blocking of filters to support flammable-gas analysis conducted in accordance with DOE/WIPP-06-3345, Waste Isolation Pilot Plant Flammable Gas Analysis (Revision 10 or later). 15 DOE-STD-5506-2021 As described in APPENDIX B and APPENDIX D, a mixture of 4% hydrogen (by volume) in air can deflagrate, but the pressure increase is relatively low and will not result in lid loss for a drum and possibly may cause a small release from drum seal failure. Based on experimental data with 55-gallon drums, lid loss can be expected at hydrogen concentrations of at least 15% in air (assuming the initial pressure is close to atmospheric). As discussed in APPENDIX D, DOE has added conservatism by selecting 8% hydrogen as the threshold for drum lid loss, to account for uncertainties. A lid that is forcefully ejected from a waste container during a deflagration presents a physical hazard to a facility worker. This hazard could cause serious injury or death to the worker and may necessitate controls for facility workers who are handling suspect drums. Analysts should not screen the hazard as an SIH.

Ignition sources include sparks, heat, static electricity, etc., that can ignite gases escaping the container, as well as potential ignition sources in the waste, such as metal objects, pyrophoric material, and heat- generating chemical reactions. More than one waste container deflagration event may be required; the exact number will depend on the number of various facility activities and the similarity of the postulated event causes and potential controls. Multiple Waste Container Deflagration (Event 7) This event is due to waste container deflagration propagating horizontally or vertically to initiate additional container deflagrations. This event requires two suspect containers (see the definition in Event 6) that can be stacked or stored/staged immediately adjacent to each other (e.g., on a pallet). More than two containers should be considered if there is a potential for multiple suspect drums to be co-located. It should also be considered for situations where multiple newly generated containers that have been recently vented are commingled until determined by headspace sampling or has a technical basis that supports that the vent is adequate to reduce to a concentration lower than 8 vol% hydrogen. Enclosure Deflagration (Event 8) For facilities using enclosures such as gloveboxes or hot cells, deflagrations within the enclosure are addressed as separate events to ensure a complete hazard evaluation. This event is caused by hydrogen or other flammable/explosive gases inside an enclosure or within a container that has been placed inside and opened within an enclosure. Flammable vapors could be concentrated or exacerbated by a loss of ventilation/purge. Ignition sources include sparks, heat, etc. that can ignite gases as well as potential ignition sources in the waste, such as metal objects, pyrophoric material, and heat-generating chemical reactions. 3.3.3 Loss of Confinement/Containment Vehicle/Equipment Impacts Waste/Waste Containers (Event 9) This event is due to operation of vehicles or equipment associated with facility operations as described in the DSA. These vehicles and equipment may or may not be used in close proximity to the TRU waste. The impact type will vary based on the impact source and may involve, for example, a container puncture by forklift tines, or a larger vehicle impact resulting in container damage. Additionally, the potential for a fuel pool fire should be evaluated when vehicles/equipment with liquid fuels are involved in impacts with waste/waste containers; see Event 1. 16 DOE-STD-5506-2021 Drop/Impact/Spill Due to Improperly Handled Container, etc. (Event 10) This event is due to mishandling of containers or to drops/impacts caused by equipment failure. This subcategory of loss of confinement events includes drops of containers from a height hitting a hard surface or containers being impacted by an energy source that is not included in another of the loss-of- confinement subcategories (e.g., loads being dropped onto containers, gas cylinder missiles, maintenance activities), resulting in a spill of radioactive or hazardous material. If TRU waste containers may be dropped from elevated surfaces—e.g., drums falling from third tier or higher (see Figure 4-3, Comparison of Drum DR and ARF×RF for Contaminated Solids in Drops, Falls, and Vehicle Crashes, example of vertical stacking) during removal—a separate event will be required to ensure a complete hazard evaluation. Section 4.4.3 provides guidance on release estimates based on two levels of impact energies.

Collapse of Stacked Containers (Event 11) This event is a collapse of a stacked array of containers. The collapse may be a failure of the containers, pallets, or other stacking media due to corrosion, defective construction, damage, or improper stacking— e.g., exceeding limits, or an unstable array. Waste Container Over-Pressurization (Event 12) This event is due to a buildup of pressure inside of a container. The pressure buildup may be due to radiolysis of water or other hydrogenous material, thermal expansion of material/gases inside the container, or chemical reactions inside the container. This is typically a slowly developing event (on the order of months), although containers with unknown material or with the potential for chemical reactions may pressurize more rapidly (on the order of hours to days). 3.3.4 Direct Exposure to Radiation Events (Event 13) This event is caused by ionizing radiation from the waste. The exposure may be due to normal operational conditions (e.g., handling, cleaning up a spill) or due to an accident that causes the loss of shielding inherent to the container/activity. If the facility processes both CH and RH TRU waste, separate events for these waste types should be included for complete hazard evaluation. 3.3.5 Criticality Events (Event 14) Criticality events can occur due to many different causes. These are typically evaluated in a Nuclear Criticality Safety Evaluation (NCSE) consistent with DOE-STD-3007-2017, Guidelines for Preparing Criticality Safety Evaluations at Department of Energy Nonreactor Nuclear Facilities. Events in the NCSE that require criticality controls should be explicitly presented in the DSA. Also, the NCSE events should be evaluated against other events in DSA to ensure that all potential upsets were considered in the NCSE. 3.3.6 Externally Initiated Events Aircraft Impact with Fire (Event 15) This event occurs when a large commercial aircraft, small general-aviation aircraft, or helicopter crashes into the facility and a fire ensues. Site over-flights and nearby airports are contributors to this event. Aircraft impact events are evaluated where deemed credible, or not screened out by other criteria, in accordance with DOE-STD-3014-2006, Accident Analysis for Aircraft Crash into Hazardous Facilities. A 17 DOE-STD-5506-2021 representative aircraft of the category indicated as credible per DOE-STD-3014 should be evaluated with a fire initiating coincident with the crash. External Vehicle Accident (Event 16) This event is due to a vehicle, not associated with facility operations, impacting the facility/waste containers. Traffic on nearby roads contributes to this event. This event differs from the vehicle impact from operational activities previously discussed (Event 9) in that the vehicle is not associated with facility operations allowed in the DSA. Additionally, if controls are necessary, the control set for this event may differ from the control set used for operations-related equipment. External Vehicle Accident with Fire (Combustible or Pool) (Event 17) This is a potential follow-on event for the external vehicle accident. After the vehicle accident, spilled combustible waste, and/or fuel from the vehicle ignite and burn. External Explosion (Event 18) This event is similar to the explosion due to mechanical failure, with missiles occurring within the facility that was discussed in Section 3.3.2.1. The hazard is primarily from vehicles/roadways near the facility or storage location, or from nearby locations with large quantities of explosive gas—for example, from a nearby gas pipeline, propane tanks, or pressurized gas used for characterization or welding.

In addition to explosion overpressures, an explosion could produce missiles that could impact containers of waste or facility SSCs. For waste in containers, the release mechanism would essentially be an impact. External Fire (Event 19) This is a fire that begins outside of the facility and propagates to the facility. The external fire could be from wildland fires, other facilities, or another fire source. If TRU waste may be within and/or outside of a building, external fires should address impacts both on waste handled/stored inside or outside of a building. 3.3.7 Natural Phenomenon Hazard Initiated Events Lightning (Event 20) A lightning strike may cause fires in the electrical system (e.g., ignition of wire insulation in electrical systems) that could ignite nearby material. Lightning strikes that cause fires outside of the facility are addressed as external fires. Additionally, lightning may strike a container or near stored/staged containers. The direct strike could cause rapid heating and pressurization of a container, with ejection of material. In the case of a direct lightning strike to an overpacked container, the overpack should not be assumed to provide any additional protection. The event should be modeled as an internal container deflagration, as described in Section 4.3.2. A direct lightning strike to an overpacked container should not be considered to prevent damage to the inner container, and this release should also be modeled as an internal deflagration. The nearby strike could cause small missiles (e.g., fragments of concrete). 18 DOE-STD-5506-2021 High Wind (Event 21) This event is due to high winds causing impacts to both the facility and the containers by falling objects. The falling objects may be nearby trees, pole, cranes, or parts of the facility structure. Tornado (Event 22) This event is due to a direct effect of a tornado, falling objects, or tornado-produced missiles causing impacts to both the facility and the containers. Missiles may be produced from various pieces of equipment or material (e.g., pallets). The falling objects may be nearby trees, poles, cranes, or parts of the facility structure. Snow/Ice/Volcanic Ash Build-up (Event 23) Accumulation of snow, ice, or volcanic ash may cause the roof of a facility or structure to collapse, or may cause nearby objects, such as trees, to fall and impact the waste containers. Seismic Event (Impact Only) (Event 24) The seismic event can cause failure of the facility structure (partial or catastrophic, depending on the facility construction), failure of equipment inside the facility, or other structure failure, which impacts the waste. Additionally, the event can cause containers to fall and spill their contents. Seismic Event with Fire (Event 25) The seismic event can cause failure of the facility, failure of equipment inside the facility, or failure of other structures, which impact the waste. Additionally, the event can cause containers to fall and spill their contents. The structural failure could involve damage to electrical systems that are not seismically qualified or involve other potential ignition sources (e.g., flammable materials or gas lines where present) that can ignite spilled combustible waste or other combustibles in the facility. Flood Event (Event 26) A flood event can cause failure of facility structures or equipment, thereby impacting integrity of waste or waste containers. Relocation of waste containers is also possible, creating the potential for a criticality where fissionable inventory remains in uncharacterized2 TRU waste in containers.

3.3.8 Chemical Initiated Events (Event 27) Chemical constituents in waste streams can lead to uncontrolled reactions with subsequent heat generation, fire, explosion, formation of toxic fumes, formation of flammable gases, formation of shock and friction sensitive compounds, and pressurization in closed vessels. Such reactions can be initiators for other events described in Section 3.3 (e.g., deflagrations) and can be caused by incompatible mixtures of chemicals. Reactions can also be initiated by environmental effects, such as temperature, humidity, and oxygen in air, that may change over time or that could be associated with an unplanned event such as a fire. These types of situations should be evaluated in the DSA where applicable, e.g., as identified by the FHA or Chemical Compatibility Evaluation (CCE). 2 The term ñuncharacterizedò as used in this Standard refers to TRU waste being stored onsite, or retrieved from burial grounds, that has not been processed to meet WIPP Waste Acceptance Criteria and may have prohibited items and/or unknown chemical constituents. 19 DOE-STD-5506-2021 An example of adverse chemical reactions is related to oxidizing chemicals in the waste matrix, both in newly repackaged containers and during storage. When such chemicals come into contact with organic materials (e.g., neutralizing or buffering agents), rapid pressurization can occur and potentially explosive compounds can develop. Determination of the potential for accidents involving oxidizing chemicals should include an evaluation of whether such chemicals may be present in the waste (i.e., process chemistry where the waste originated and associated chemical constituents), relative quantities and concentration of chemicals present in the waste stream (especially concerned with strong acids), actions or additions to the waste planned during repackaging efforts, and stability of repackaged waste during storage (e.g., engineered organic polymer sorbents). Additional information on oxidizing chemical hazards can be found in DOE/WIPP-17-3589, Basis of Knowledge for Evaluating Oxidizing Chemicals in TRU Waste (Revision 1 or later). The resource is useful in evaluating waste with one or more oxidizing chemicals. Another example hazard that may exist at some DOE sites (e.g., operations involving unique chemicals), are chemicals that are or may become shock-sensitive. Materials such as perchloric acid and other peroxide-formers can leave behind sensitive crystalline structures (e.g., on lids of laboratory beakers or containers) that are vulnerable to energetic reactions upon impact or jarring. The hazard analysis shall include an evaluation of the chemicals potentially in the waste to consider whether adverse chemical reactions could occur. This evaluation should determine whether chemicals are present in a quantity or form sufficient to produce adverse reactions and whether reactions can be created by combinations of waste with incompatible chemicals. Chemicals should only be excluded from evaluation with technical justification. Chemicals that are present in small quantities can still play an important role in the progression of a chemical reaction. A CCE is a required part of the Waste Isolation Pilot Plant waste certification process and is based on the method described in the 1980 EPA method EPA-600/2-80-076, A Method for Determining Compatibility of Hazardous Waste. This evaluation is intended to identify and evaluate potential reactions between dominant and minor chemical constituents within the waste stream and demonstrate that the waste will not lead to unanticipated or disastrous effects—will not, for example:

• Generate extreme heat or pressure, fire or explosions, or violent reactions, • Produce uncontrolled toxic mists, fumes, dusts, or gases in sufficient quantities to threaten human health or the environment; • Produce uncontrolled flammable fumes or gases in sufficient quantities to pose a risk of fire or explosions; • Damage the structural integrity of the device or facility; • Threaten, through other like means, human health or the environment. This methodology also addresses various waste-management scenarios, including situations where waste creator records may be inadequate (e.g., some uncharacterized waste streams). The EPA methodology is a useful tool for assessing chemical hazards in transuranic waste. This approach, or other systematic evaluation techniques, should be employed during DSA development to ensure a complete evaluation of 20 DOE-STD-5506-2021 chemical hazards. The evaluation should identify the chemicals that are potentially in (or in contact with) the waste, and should assess combinations of those chemicals to determine whether the waste could participate in adverse reactions. Overall, the chemical compatibility evaluations should analyze: • the origin of waste, including process chemistry from which it was generated and any off-normal conditions (e.g., spills), • relative quantities and concentration of chemicals present in the waste stream, • storage environment (e.g., temperature, slow reactions as the waste ages, and potential reactions with air or water), • actions or additions to the waste planned during repackaging efforts, • stability of repackaged waste during storage. Maximum possible use should be made of existing information from previous or current WIPP certification campaigns, such as the required acceptable knowledge (AK) documentation and available CCEs performed to meet WIPP requirements. The National TRU Program non-conformance reports should also be routinely evaluated for potential issues related to chemical reactions. In some cases, waste records and AK documentation may not be sufficient to determine whether chemical constituents are present within waste streams. A careful review of the origin of waste, including facility processes from which it was generated, is necessary as part of the hazard identification process. Representative waste samples can be collected and analyzed, where feasible, to help determine waste characteristics. When this data or other technical basis is not available, the DSA should assume the presence of chemical constituents used in previous facility processes that generated the waste. The DSA should also analyze additional hazards associated with waste processing and repackaging activities and account for potential adverse effects of additives or mixing of incompatible chemicals. 3.4 Expected Operational Events A facility’s DSA addresses normal, abnormal, and accident conditions as required by 10 CFR Part 830. A subset of the events evaluated in the DSA includes certain operational events that are expected to occur during the lifetime of a given TRU waste operation even with preventive controls in place. As used in this Standard, expected events are defined as planned occurrences encountered during normal operations that result from hazards inherent to the material and activities. This definition does not include events caused by personnel errors, since these causes involve a control failure that warrants some level of investigation. For example, incidental fires or reactions might be expected during retrieval and excavation of TRU wastes involving flammable/explosive atmospheres.

In cases where an expected operational event occurs, it is prudent to validate that established protective measures function as intended, and then resume operations. This is similar in concept to initiating authorized required actions when a Limiting Condition for Operation (LCO) condition is entered. The DOE acknowledges the potential for the event and adequacy of the protective measures through approval of the DSA. Approval of a DSA in which response actions are cited for specified “expected events” 21 DOE-STD-5506-2021 effectively authorizes work to continue once the event conditions are evaluated, reported (where necessary in accordance with DOE O 231.1B, Environment, Safety and Health Reporting, or DOE O 232.2A, Occurrence Reporting and Processing of Operations Information), and it is confirmed that the expected event occurred as planned and no unanticipated behavior or consequences (e.g., worker injury) were exhibited. It should be noted that DSA coverage of an “expected operational event” does not apply to situations in which it is determined that a potentially inadequate safety analysis exist as discussed in 10 CFR 830, Subpart B (i.e., an operational event related to errors, inappropriate value, or otherwise inadequate analysis in the DSA). For the purposes of this Standard, an expected operational event involves known hazards that are described in the DSA, and which does not result in significant consequences to workers or the public with preventive and mitigative controls in place. In other words, the protective features provided to perform operational processes ensure consequences are within the operational standards that apply to the work. For example, worker dose is limited to criteria established in 10 CFR Part 835, Occupational Radiation Protection. The DSA provisions for documenting expected operational events are as follows: • The event is documented in the facility process description of the DSA • The response actions following occurrence of the expected event are specifically documented in the DSA, although they may be as simple as “Evaluate and report the event to DOE” (where necessary in accordance with DOE O 231.1B and DOE O 232.2A). • The event is analyzed in the DSA hazard evaluation. • Worker protection measures for the operational event are identified in the DSA. A primary benefit of identifying expected operational events is to provide DOE with the means of pre- approving actions for continued operation should certain events that meet the conditions of an expected event occur. Because these events are expected, appropriate protective measures and actions to ensure continuation of operations shall be identified and in place prior to beginning the operation. DOE-STD-5506-2021 22 TRU Waste Source Term Analysis 4.1 Purpose This section provides guidance on source term development. The Source Term (ST) is the amount of airborne respirable radioactive material released to the environment. As specified in DOE-HDBK-3010- 94, Airborne Release Fractions/Rates and Respirable Fractions for Nonreactor Nuclear Facilities, ST is used as part of the analysis of hazards/accidents and is determined by the following five-factor formula: ST = MAR·× DR × ARF × RF × LPF Where, MAR = Material-at-Risk is the amount of radionuclides available to be acted on by a given physical stress. DR = Damage Ratio or fraction of the MAR that is impacted by the postulated accident scenario, unitless ARF = Airborne Release Fraction, unitless

RF = Respirable Fraction, unitless LPF = Leakpath Factor, unitless Additional information on unmitigated analysis methodology and assumptions can be found in DOE- STD-3009-2014 and DOE-HDBK-1224-2018. 4.2 Material-at-Risk The amount of hazardous material that is assumed to be at risk from a postulated accident scenario, or MAR, will directly impact the doses received by both workers and the public. An overly conservative estimate of the MAR could very well lead to establishment of unnecessary controls and an ineffective use of resources. On the other hand, an optimistic (non-conservative) analysis could lead to major impacts on operations by discovering discrepant as-found-conditions, Potential Inadequacies in the Safety Analysis (PISAs), preparation of multiple Unreviewed Safety Questions (USQs) determinations, and even potentially creating conditions that could lead to accidents. Thus, there is a need to balance the level of conservatism associated with the MAR definition. 4.2.1 Data Uncertainties in Hazard and Accident Analysis The purpose of determining MAR estimates during Hazard Analysis (HA) and Accident Analysis (AA) is to identify a bounding value for the scenario being evaluated. During the HA, qualitative consequence severity categories are assigned to each of the postulated accident scenarios. Thus, there is a need for an understanding of the MAR expected to be involved. During AA, a more quantitative knowledge of the anticipated MAR is expected and is based on a quantitative assessment of the effects of the postulated release, a assessment that considers factors such as inventory, material form, and the energy sources involved with the release. Data uncertainties associated with the MAR depend on many variables, such as the quality of the current inventory data, whether the data represents Acceptable Knowledge (AK) for uncharacterized waste or 23 DOE-STD-5506-2021 newly generated waste, and whether the inventory is based on actual characterization data. Most uncertainties associated with uncharacterized waste stem from the fact that requirements for—and formality associated with—AK documentation have changed significantly, with the requirements for the older documentation being less stringent than current requirements. Thus, uncertainties associated with characterized waste are much less significant (e.g., intrinsic uncertainties associated with NDA and NDE). 4.2.2 Defining a Bounding MAR for TRU Operations Table 4-1, Bounding MAR Approach for TRU Waste Operations, summarizes a bounding MAR approach that may be applied for TRU waste operations. The table provides an algorithm of MAR values based on the number of containers anticipated to be impacted by postulated scenarios (single container, payload, building, etc.), and inventory knowledge (e.g., whether the inventory has been partially or fully characterized). In cases where no characterization data is available, inventory estimates should be based on existing process knowledge or the use or extrapolation of characterization data from similar waste streams. The quantities of TRU material presented in Table 4-1 follow the general algorithm that • A single container scenario assumes the presence of the single maximum loaded container (including instrument uncertainty), while • Multiple container accident scenarios assume the presence of some combination of containers containing the maximum container value, the 99th percentile value, the 95th percentile value, and the mean value quantities of TRU material, from the population of containers being evaluated.

The algorithm also accounts for the extent of characterization associated with the inventory (limited or partial characterization, and fully characterized, e.g., WIPP compliant assay). The use of an additional 20% margin is recommended for single-container events in which the container is not characterized or has limited characterization (e.g., not fully WIPP-compliant or otherwise acceptably characterized). A higher margin may be warranted for waste retrieval activities (i.e., from burial grounds) when container integrity or waste data records are questionable or unknown. In these cases, assumptions should be specifically derived in the DSA. The methodology in Table 4-1 provides for additional conservatism to account for the increased uncertainty when the waste containers involved in the accident are not fully characterized. For those inventory populations with only limited or partial characterization, the MAR value shall be based on the non-parametric estimate of the 95% upper tolerance limit (UTL95) for the specified percentiles and the 95% upper confidence limit (UCL95) for the mean (arithmetic average); see APPENDIX A. Container populations, for which individual container inventories have all been determined, through measurement (and documented), may be considered to be fully characterized for application of the algorithm in Table 4-1. The MAR approach in Table 4-1 defines a bounding approach for typical TRU waste operations. This approach, however, is intended to be used only in operations in which containers are randomly selected or placed within storage without a bias toward waste type or characteristic (e.g., high MAR containers segregated from a population). The MAR methodology is not intended for the following situations: DOE-STD-5506-2021 24 • Operations that intentionally commingle containers from the upper end of the facility’s distribution of radioactive material (e.g., the highest two or three containers in the same array that is impacted by an accident stress); • Operations in which it can’t be distinguished whether containers with the highest distribution of radioactive material are commingled in a facility’s inventory (e.g., retrieval of uncharacterized TRU waste in containers from burial grounds without data supporting such assumptions); or • Containers that have been prepared for shipment in accordance with limits established in the WIPP waste acceptance criteria where containers are repackaged to the maximum of such limits (i.e., versus a practice such as one-for-one parent-to-daughter drum repackaging). In the first two situations, the term “commingling” is relative to the proximity of containers that are concentrated in an area that can be impacted by a single accident stress—e.g., intentionally concentrating together or segregating high-MAR drums from the general population of drums.

The MAR approach in Table 4-1 should consider the combination of source-term factors that produce a conservative result. When a facility has a variety of waste types and container types, the DSA shall include assumptions that lead to a bounding source term, as opposed to a bounding MAR (unless otherwise directed in the guidance provided for specific events such as seismic impacts). These assumptions include a combination of factors, including the material form, the release fraction, individual container MAR loading, container response to event stress, and event MAR distribution to derive the conservative source term for the event. For example, for a fuel pool fire accident in which some containers lose their lids and others do not, the analyst would assume that the maximum container is in the population with lid loss. The MAR statistical method may be applied to subpopulations of containers within a facility (i.e., a portion of the overall containers that exists at a particular facility area), provided that the subpopulation meets the criteria for using Table 4-1. The subpopulation may be defined with separate MAR statistics (max, 95th percentile, mean) based on container type, MAR form, or other waste characteristics as supported by facility inventory controls. These methods for defining subpopulations may only be used if the MAR form and waste characteristics are well-understood. Additionally, the subpopulation shall not be subject to accident stresses that can simultaneously affect the remaining facility population of containers that lie outside the sub-population. When using the MAR approach in Table 4-1, assumptions regarding the scope of container handling, staging, and storage shall be clearly stated in the DSA. DSA assumptions shall be reviewed periodically as necessary to ensure that MAR statistics have not changed in a non-conservative direction. Elements of safety management programs relied on to ensure MAR statistics remain conservative and up to date should also be discussed in the DSA (e.g., container management). Administrative controls should be used to protect assumptions and conclusions of the hazard/accident analysis. These include specific limits (e.g., MAR container/area limits) or assumptions (e.g., combustible/noncombustible waste fractions) in the TSR that ensure the analysis remains valid or that are derived in the DSA mitigated analysis to ensure that accident consequences are not significant. Administrative controls should also be used to prohibit certain activities when there is potential that such activities could concentrate problematic containers, thereby invalidating the MAR methodology. Administrative controls should be evaluated to determine whether they should be designated as specific DOE-STD-5506-2021 25 administrative controls (SACs), based on requirements in DOE-STD-3009-2014 and DOE- STD-1186-2016 (e.g., when the administrative control is the basis for validity of the hazard or accident analyses). Table 4-1. Bounding MAR Approach for TRU Waste Operations As an alternative to using a statistical MAR approach, process areas with a known throughput of inventory (e.g., TRU staging pad) may establish a bounding MAR limit that is used in the unmitigated analysis. In these cases, any subset of the full facility inventory should be justified on the basis that it contains the maximum inventory that could be impacted by an accident stress. For example, if planned activities are such that a limit of 1,000 plutonium equivalent curies (PE-Ci)3 is sufficient to bound the MAR based on known container loadings to be staged in a given area, then the unmitigated MAR could be established at this limit. In such a case, the limit shall be protected with an inventory limit Specific Administrative Control (SAC).

To simplify the modeling approach for a particular accident, drum contents may be assumed to be a single bounding waste form (e.g., 100% combustible contaminated solid wastes for a fire). If a site can justify 3 A dose-equivalent-curie concept effectively converts radiological consequences for individual isotopes or mixes of isotopes to the same consequences from a corresponding amount of a base isotope. For example, for Pu-239, a PE-Ci is defined as the summation of the curies of each isotope multiplied by its dose-equivalence factor. The normalization is often based on the inhalation pathway only. It is derived from the ratio of the inhalation committed effective dose for each radionuclide to that of Pu-239. This ratio is the dose-equivalence factor of the isotope per curie of isotope. This approach should not be used for radionuclides that can pose a non-negligible external dose. 26 DOE-STD-5506-2021 bounding estimates for the distribution of combustible vs. other forms (e.g., 40% combustibles and 60% noncombustibles), the appropriate ARFs and RFs from DOE-HDBK-3010-94 and Section 4.4 of this Standard should be applied for the applicable segmented waste. This approach is intended to support an overall conservative analysis as required for DOE-STD-3009-2014. It is intended to be used only for TRU waste storage operations in which containers are randomly selected or placed within storage without a bias toward waste type or characteristic (e.g., all combustible waste containers segregated from the general population that would have higher release potential). The application of a waste form distribution for a particular accident is not intended for the following situations: • Operations that intentionally commingle containers with the highest distribution of combustible waste material or other form of material that may have a higher release potential (e.g., the highest few containers in the same array that is impacted by an accident stress that could invalidate the waste form distribution); or • Operations in which it can’t be distinguished whether containers with the highest distribution of combustible material or other form of material that may have a higher release potential are commingled in a storage location (e.g., retrieval of uncertified containers without data supporting such assumptions). In the above situations, the term “commingling” is relative to the proximity of containers that are concentrated in an area that can be impacted by a single accident stress such as a fire—e.g., intentionally concentrating together or segregating high-combustible drums from the general population of drums. For this situation, the analysis should consider the waste forms that could be present in the facility, and assume that the waste involved in the accident is of the form that gives the bounding source term. 4.3 Damage Ratios The DR is one of the parameters of the “five-factor formula” presented in the DOE-HDBK-3010-94 for estimating the airborne radiological release from an accident. The DR is defined in DOE-HDBK-3010-94 as the “fraction of the MAR actually impacted by the accident-generated conditions.” However, there is a degree of interdependence between the definitions of DR and MAR. If only the MAR directly affected is used, then the DR is 1.0. The DR may be less than 1.0, depending on the accident. What is important is that one convention be used consistently to avoid an obvious potential for assigning incorrect DR values.

The DR is estimated based upon engineering analysis of the response of structural materials and materials-of-construction for containment to the type and level of stress/force generated by the event. Standard engineering approximations are typically used. These approximations often include a degree of conservatism due to simplification of phenomena to obtain a usable model, but the purpose of the approximation is to obtain, to the degree possible, a realistic understanding of potential effects. The DR term is used in a variety of ways in this Standard to account for the MAR affected and overall source term and may involve multiple adjustment factors. For example, in complex accidents where different portions of MAR undergo different accident stresses, DRs are assigned to fractions of MAR for the different release pathways, such as for a drum deflagration where a fraction of MAR is ejected, releasing material from shock-vibration and subsequent unconfined burning of combustible material, and confined burning of contents remaining in the drum. In other cases, DRs account for the protection 27 DOE-STD-5506-2021 provided by a container, or to adjust ARFs and RFs based on multiple accident stresses. In such complex cases, attention is needed to ensure mathematical consistency and to avoid double-counting that reduces the source term impacted by an accident. A DR of 1.0 is often assumed, either for simplicity in performing the calculations as suggested in the DOE-HDBK-3010-94 or based on conservatism if the final radiological consequences do not drive the need for special TSRs to prevent or mitigate the accident. Section 7.3.6.2 of the DOE-HDBK-3010-94 provides a very important perspective on assigning DRs: In the examples in this handbook, DRs are typically bounded by assuming a value of 1.0 for the sake of simplicity. The above discussion indicates how conservative such a bound can be. It is important not to lose sight of the fact that the phenomena being examined are generally unlikely to highly unlikely. By the time a maximum MAR has been assumed, the DR has been maximized as 1.0, the bounding ARFs and RFs of this document have been applied, no leakpath is accounted for, and 95% or greater meteorology has been used for dispersion, the answer obtained is extreme. Objectivity must be retained in the evaluation process so that a rote conception does not distract available resources from areas where greater real gains in safety can be made. As previously cautioned in this handbook, answers obtained are only as good as the decisions they lead to. That perspective should be kept in mind when DRs are justified for any specific accident scenario, natural phenomena event, or external events. The selection of appropriate DRs shall support an overall conservative analysis consistent with the DOE-STD-3009-2014 (or applicable safe harbor standard) methodology. DRs are also selected in context with the conservatisms of the other parameters in the “five factor formula,” i.e., MAR; bounding ARFs and RFs per DOE-HDBK-3010-94; and Leakpath Factor (only for mitigated analysis).

When applying the methodologies in Section 4.3 of the Standard, there are cases where modeling a smaller number of drums would be more conservative. After determining the number of drums that could be involved in an event as recommended in this section, the analyst should consider whether a smaller number of drums could be more conservative. If the smaller number of drums yields a more conservative result, then the smaller number shall be used. For example, Section 4.3.3.2, Drums Exposed by Ordinary Combustible Fires, allows for a 0.5 DR for less than 10 drums exposed to an ordinary combustible fire. Applying the Table 4-1 limited characterization algorithm and assuming that a maximum drum has 300 PE-Ci, the UTL95 for the 99th percentile drum is 90 PE-Ci, the UTL95 for the 95th percentile drum is 10 PE-Ci, and the UCL95 for the mean drum is 3 PE-Ci, the MAR involved for 100 drums is 698 PE-Ci with a 0.5 DR or an effective MAR of 349 PE-Ci. However, nine (9) drums have a MAR of 425 PE-Ci with a 1.0 DR, therefore is more bounding. The following subsections address container integrity. They also identify conservative DRs for drum deflagrations, fires, container loss of confinement (low-energy and high-energy mechanical insults), and natural-phenomenon events. These DRs are used in both the DSA unmitigated and mitigated 28 DOE-STD-5506-2021 hazard/accident analysis. Safety classification of containers should be determined in accordance with the applicable 10 CFR 830, Subpart B, safe-harbor methodology. Consistent with DOE guidance, qualitative bases for classification of containers may be used. Contact-handled (CH) TRU wastes are packaged and shipped for disposal to the Waste Isolation Pilot Plant (WIPP) in U.S. Department of Transportation (DOT) 7A containers. The latest version (March 2013) of the CH TRAMPAC document on the National TRU Programs portal lists the following containers as “Payload Container Assemblies,” i.e., Type 7A CH containers: • 55-gallon metal drum (and other sizes) • Pipe Overpack Container (POC) • Standard Waste Box (SWB) • Ten Drum Overpack (TDOP) • Standard Large Box 2 (SLB2) • Criticality Control Overpack (CCO) • Shielded Container Assembly (SCA) The performance of these containers under various accident stresses are similar for some of the container types but are not the same for all of them. APPENDIX C summarizes which containers are considered to be equivalent to each other for accident types, based on the technical evaluations of them for the WIPP safety basis. All containers are not specifically identified in the discussions throughout the remainder of this section. The discussion, however, applies to the equivalent container unless unique differences are elaborated. 4.3.1 Container Integrity DOT 7A or equivalent containers purchased for the packaging and storage of TRU waste provide containment of radioactive materials and minimize release of radioactive material to the public and workers. DOT 7A containers meet the performance testing requirements specified in 49 CFR Part 173, Shippers – General Requirements for Shipments and Packaging. Those requirements include performance testing which demonstrates that the containers can withstand the following types of normal handling and accident conditions: • Water spray test • Free drop test • Penetration test • Stacking test

When purchased, TRU waste containers are certified to DOT specifications. However, containers can degrade over time, and DOT certification is effective for only one year after packaging. TRU waste containers greater than one year old, therefore, have lost their DOT certification, even though they have not stopped performing their intended function (hereafter, these are referred to as “uncertified” containers). Type 7A containers that meet DOT specifications and conditions most applicable to DOE TRU waste activities are qualified to withstand an impact from a 4-ft drop onto a hard surface without being breached. It is not reasonable to assume that the structural capability of a container more than one year old has diminished significantly or that these containers will split open upon any impact. This is supported by field experience during handling, movement and storage evolutions. Although handling activities do not 29 DOE-STD-5506-2021 subject the containers to the same loads as does an impact from a drop, these activities, along with regular inspections, do provide some evidence that most of the containers have maintained structural capability. During storage, handling, and movement, TRU waste containers may be punctured, crushed, toppled, or dropped, causing failure of the container and release of material. Uncertified container performance and the degree of damage from these accident stresses are largely dependent on the structural integrity of the container. Several individual-drum drop tests and palletized-drum drop tests have been conducted and conclude that uncertified drums will maintain confinement from a 4-ft drop, because any small degradation is likely to be less than the margin of safety in the original drum design. The WIPP CH WAC recognizes that most TRU containers are no longer certified. It therefore provides an inspection checklist to document that a container meets the DOT 7A criteria. WIPP has established these criteria to address uncertified containers and qualify them against new container requirements. By applying the WIPP criteria to uncertified containers, they can be deemed DOT Type 7A-compliant. It is reasonable to conclude that containers that satisfy the WIPP container criteria may also be credited as meeting DOT specifications during storage. The WAC states: Acceptance Criterion for CH-TRU and RH-TRU Waste. Both CH-TRU and RH-TRU waste payload containers shall – • meet U.S. Department of Transportation (DOT) Specification 7A, Type A, packaging requirements delineated in 49 CFR 173.465 (Reference 4, Section 2.3.2; Reference 10, Attachment A1, Section A1-1b), • be made of steel and be in good and unimpaired condition prior to shipment from the DOE sites. To demonstrate compliance with the requirement that payload containers be in good and unimpaired condition, the exterior of all payload containers shall undergo 100% visual inspection prior to loading into an authorized package. The results of this visual inspection shall be documented using the Payload Container Integrity Checklist contained in Appendix D. A payload container in good and unimpaired condition, 1) does not have significant rusting, 2) is of sound structural integrity, and 3) does not show signs of leakage. Significant rusting is a readily observable loss of metal due to oxidation (e.g., flaking, bubbling, or pitting) that causes degradation of the payload container’s structural integrity. Rusting that causes discoloration of the payload container surface or consists of minor flaking is not considered significant. A payload container is not of sound structural integrity if it has breaches or significant denting or deformation. Breaching is defined as a penetration in the payload container that exposes the internals of the container. Significant denting or deformation is defined as damage to the payload container that results in

DOE-STD-5506-2021 30 creasing, cracking, or gouging of the metal, or damage that affects payload container closure. Dents or deformations that do not result in creasing, cracking, or gouging or affect payload container closure are not considered significant. • be reported to the WWIS database referencing the number and types of payload containers planned for shipment to the WIPP. These criteria have been assembled into a verification checklist, provided in Table 4-2. It should be noted that the WIPP WAC and container-integrity checklist criteria are subject to change based on field experience and feedback. The Table 4-2 criteria are based on DOE/WIPP-02-3122, Contact Handled Transuranic Waste Acceptance Criteria for the Waste Isolation Pilot Plant, that was in effect at the time of development of this Standard. The most current criteria shall be used to determine sound structural integrity of TRU containers. The use of damage ratios specified in the Standard (i.e., DR < 1) are based on containers with sound integrity that meet these criteria. This applies to both direct-loaded and overpacked containers. An overpacked container is a metal container of sound integrity nested within a larger metal container of sound integrity (e.g., a drum, SWB, or Ten Drum Overpack [TDOP]). Application of these criteria assumes container integrity can be verified through an inspection program or process knowledge. Where this cannot be accomplished (e.g., TRU waste retrieval from a burial ground), a DR of less than 1 requires explicit justification. Additionally, in cases where a criterion is met in Table 4-2, Payload Container Integrity Checklist, the uncertified container cannot be assumed to be of sound integrity. Containers that are discovered to not be of sound integrity should be addressed per the site’s procedures for managing waste containers, and if necessary, might require specific TSR controls beyond those listed in Table 5-1. If a DSA uses the damage ratios in this Standard for containerized waste, the DSA shall document the basis for assuming that the containers have sound integrity (e.g., regular inspections). DOE-STD-5506-2021 31 Table 4-2. Payload Container Integrity Checklist 32 DOE-STD-5506-2021 4.3.2 Container Deflagration Events A container deflagration occurs when flammables (gases or vapors) inside the vapor space of a container ignite. The gases burn, with the flame front advancing at subsonic speeds (in contrast to a detonation). Heat and combustion products are released, leading to a rapid increase of pressure inside the container. Depending on the circumstances, the lid of the container may or may not be ejected. Waste can be released from the container as the excess pressure is vented through mechanisms such as lid loss, seal failure, and vent failure. The deflagration can also ignite the contents of the container and/or ejected materials, leading to airborne releases. Three components are necessary for burning: fuel, oxidant, and an ignition source. Other factors will affect the ignition and combustion of fuel–air mixtures, such as concentrations of the reactants, the location of the ignition source, and presence of water vapor. Sufficient oxygen is assumed to be present unless a lack of it can be technically justified. An ignition source should always be assumed to be present for the unmitigated analysis.

The radiolysis of hydrogenous materials by the activity present in TRU waste generates hydrogen gas that may accumulate in the drums and other waste containers. Based on drum characterization studies for unvented drums, the oxygen content is simultaneously reduced, likely due to reaction with other materials present or hydrogen and oxygen forming water vapor, although this reduction could be offset by in- leakage past container seals due to breathing caused by barometric pressure and atmospheric temperature changes. However, characterization of unvented drums at the Savannah River Site has demonstrated that sufficient levels of oxygen are sometimes present to support combustion, in conjunction with levels of hydrogen that exceed its Lower Flammability Limit (see discussion in APPENDIX B). The vents in vented containers provide an additional pathway for fresh oxygen to enter the container, so it should also be assumed that such containers have sufficient oxygen. Contained gases can explode (deflagrate or detonate) and result in loss of containment and ejection of surface-contaminated combustible contents. The energy release and the duration of the energy release is a function of the explosive reaction: deflagration or detonation. When the fuel and oxidant are in a gaseous state, the flammable mixtures deflagrate (fast burning), but under special conditions (such as proper concentration of the component gases, turbulent mixing, a strong ignition source, an adequate length/diameter ratio, run-up distance, etc.), a deflagration can transition into a detonation, in what’s known as a Deflagration- to-Detonation Transition. This phenomenon is addressed in APPENDIX B and APPENDIX D, which conclude that a deflagration in a drum will not transition to a detonation for most TRU waste packaged per standard practices in the DOE Complex when initially generated. However, if a site determines that they have a detonation hazard, then the methodology for analyzing deflagrations in this Standard does not apply. The guidance for analyzing detonations is provided in DOE-HDBK-3010-94. There are many published experimental studies on the behavior of metal drums in the literature. Those that are relevant and available are reviewed in APPENDIX B, which summarizes hydrogen and oxygen concentrations measured in uncharacterized TRU waste in drums, provides the basis for the drum deflagration DRs, and covers the factors that influence the behavior of the contents of the 55-gallon metal TRU waste drums. 33 DOE-STD-5506-2021 The Idaho drum deflagration tests discussed in APPENDIX B indicated that sympathetic deflagration of a drum on top of the initial deflagration occurred. However, the lower drum did not lose its lid, due to the weight of the drum on top. No experimentation has been conducted nor observed on sympathetic deflagration of horizontally adjacent drums. Therefore, it is conservatively assumed that sympathetic deflagration is possible involving two suspect drums as defined by Event 7 in Section 3.3.2.3.

Although additional sympathetic drum deflagrations may be possible depending on the staging configuration and other factors, modeling more than two drum deflagrations is not deemed necessary, because adequate insights from the two-drum deflagration should be sufficient to establish appropriate controls to protect the facility worker, other onsite (co-located) workers, the public, and the environment, and based on the likelihood of three or more sympathetic deflagrations being very low, this is not perceived to be a significant risk. However, if multiple suspect drums are intentionally co-located such as for remediation, two or more sympathetic deflagrations should be evaluated for the unmitigated analysis to correspond to the number of suspect containers being staged/stored. The mitigated analysis should consider whether drums should be physically separated from adjacent drums to that could cause a sympathetic deflagration. Releases from deflagrations > 8% hydrogen (by volume) in air involving combustible waste (e.g., cellulosic material and contaminated plastic) are assumed to bound releases from surface contaminated noncombustible solids. The contents of many drums are almost entirely combustible materials composed of cellulose and plastic substrates. These combustible materials are often present as a multilayer wrapped matrix, especially for glovebox waste with the highest potential inventory. For example, combustible waste is placed in a plastic bag with air expelled before sealing for ease of handling and space considerations, then placed in a heavy-wall plastic sleeve during extraction from the glovebox. The conservative estimates of DRs for a deflagration within a container of contaminated combustible solids from various initiating events (e.g., internal spark during material handling, impacts to drums), are addressed. The accident phenomenology is described in APPENDIX B, Container Deflagrations. The explosion ejects the drum lid and a fraction of the contents. Radioactive material is released to the environment from three accident stresses: • Shock-vibration during ejection and impact with a hard surface; • Assumed unconfined burning of a fraction of the material ejected; and • Assumed burning of the remaining materials inside the drum. Appropriate ARFs and RFs for the different contributions are described in Section 4.4. The MAR associated with a single, bounding drum or a two-drum deflagration are determined as described in Section 4.2. The damage ratios in Table 4-3, Drum Deflagration Fractions of MAR, do not apply to finely divided powders. The following DRs for deflagrations within a drum, which are summarized in Table 4-3, shall be used, unless otherwise justified, for contaminated combustible solids in metal drums: DOE-STD-5506-2021 34 Table 4-3. Drum Deflagration Fractions of MAR • Single, Bounding Drum o 40% ejected = 0.4 fraction ejected based on the maximum value cited in the Idaho experiment evaluated in APPENDIX B. This 0.4 fraction ejected applies to the shock–vibration of the material as it is ejected and impacts the ground/floor and the unconfined burning outside the drum.

 Fraction of material that is released from the drum and burns in the ambient atmosphere as unconfined material: 0.05 burn fraction of the 0.4 mass of ejected combustibles that is ignited by heat generated by the combustion of a stoichiometric H2–air concentration in the drum. This includes the total energy generated by the deflagration of a 30-vol% hydrogen in air (that is assumed to contain a sufficient oxygen concentration for the complete combustion of the hydrogen) and ignoring any heat transfer to other components such as waste remaining in the drum or the drum itself and the possible extinguishment during its flight (see APPENDIX B discussion). o 60% for the remainder of the material in the drum that is conservatively assumed to burn, modeled as confined materials. o Two-drum Deflagration o Both Drums: Use the values for the single, bounding drum deflagration (i.e., 40% ejected with 0.05 burn fraction), and 60% burning inside the drums, as discussed in APPENDIX B). It should be noted that some containers hold an inventory consisting of almost entirely noncombustible, relatively nondispersible items. The radioactive constituents of these containers are most commonly found as residual surface contamination on noncombustible items (e.g., metal components) and equipment. Since this form does not burn, releases from it in a hydrogen deflagration, which is less likely due to less radiolysis-generated hydrogen, are bounded by the case of combustibles defined above. See Section 4.4.1 for further discussion on noncombustible waste forms should they need to be evaluated. Unique forms of waste (e.g., liquids absorbed on diatomaceous earth, sorbed organic liquids, dried sludges, or bulk powders) may present deflagration hazards if present in unusual configurations (e.g., internally sealed containers) or large quantities. The bulk powders could be finely divided. A substantial release can occur when the container vents the deflagration pressure. Lid loss is not necessary for a release, as material may be released through seal failure or vent failure. Where it is determined this 35 DOE-STD-5506-2021 potential hazard exists, it should be analyzed with a DR of 1.0, unless a technical basis for a different value is established (e.g., ensure that DRs are not double-counting phenomena that are already included in the ARF value). ARF×RF values should be derived from the information in Section 4.4 of this standard or DOE-HDBK-3010-94. At a given volume fraction of fuel, methane deflagrations lead to higher pressures than hydrogen deflagrations. However, a stoichiometric mixture of methane and air has less fuel than a stoichiometric mixture of hydrogen and air. Combining both effects, the maximum possible pressure rise for methane is similar to that of hydrogen. This conclusion is supported by test data documented in Cashdollar 2000 and Salzano 2012, which indicates a relative difference between deflagration pressures from the two gas mixtures of ≤ 15%. These tests were conducted using varying container sizes and initial pressures. Theoretical (adiabatic) calculations presented along with the tests showed a slightly narrower range of deflagration pressure difference, ≤ 10%. Therefore, it is appropriate to model methane deflagration in a TRU waste container the same as depicted in Table 4-3 for hydrogen deflagration.

The potential presence of prohibited items (e.g., cylinders of flammable/combustibles gases, VOCs) in uncharacterized waste also can generate flammable gas mixtures. Other reactions (e.g., chemical, microbial) can generate flammable gases, or sorbed organic materials can evaporate, leading to flammable vapors. APPENDIX B concludes that the behavior of TRU waste drums filled with combustible waste containing a limited quantity of VOC is bounded by the drum behavior resulting from the deflagration of an internal stoichiometric H2–air mixture. This applies to both the ejection fraction and the amount of combustibles that could burn outside the drum. Although the quantity of the VOC is small, under most TRU waste drum situations, larger quantities are not anticipated. Under special circumstances for drums containing liquid VOC or large quantities of cellulose wetted with solvents used to clean glove box interior that are packaged, larger quantities of VOC may be found. This situation would not be bounded by the H2 drum deflagration due to the amount of solvent-soaked combustibles that could burn outside the drum, and the possibility that a larger fraction of wastes may be ejected. For combustible solid wastes with large quantities of VOCs (e.g., quantity exceeds the WIPP WAC requirement that observable liquid is less than 1 percent by volume of the outermost container at the time of radiography or visual examination) or a container with substantial sorbed organic liquids, a DR of 1.0 is conservatively assumed for ejection of 100% of combustible wastes and unconfined burning due to the lack of experimental data and uncertainty of what can occur under these conditions. If the contents are radioactive flammable or combustible liquids and have no combustible solid wastes, the release is modeled per recommendations in the DOE-HDBK-3010-94, assuming a DR of 1.0 for lid loss and subsequent burning of all the liquid. Damage ratios for internal deflagrations for other container types are addressed as follows, along with corresponding ARF and RFs. The release models discussed above are for contaminated combustible solids (e.g., wipes, gloves, plastic sheets). Other waste forms, such as bulk powders, liquids absorbed on diatomaceous earth, sorbed organic liquids, and dried sludges, that may be direct loaded into a container, require individual evaluation consistent with Table 4-8. For a direct-loaded Standard Waste Box (SWB), lid loss is not expected as a result of a deflagration, because the lid is very heavy and bolted onto the body of the box. No loss of lid was DOE-STD-5506-2021 36 observed by deflagration testing of a SWB by the Southwest Research Institute (SWRI), as discussed in APPENDIX B, Section B.2.9, Deflagration Testing for CH Payload Containers and Filter Vents at Southwest Research Institute, albeit, the experiment reported results, which reported a maximum event pressure of 20 psig, are not fully conclusive of deflagration event overpressures. However, a release from potential venting of particulates through breaches of the outer container gasket and vent filter media is expected, because test results indicated that a flour–fluorescein mixture leaked from the SWB. Therefore, a DR of 1.0 is assumed since the SWB gaskets can be affected by pressure rise from the deflagration. This DR is combined with an ARF×RF of 5E-4 from Section 4.4.2 and Table 4-8 that assumes confined burning of combustible wastes, which represents a conservative source term estimate that bounds shock–vibration and low-energy impact effects or container overpressure (ARF×RF of 1E-4 Table 4-8) from the deflagration.

Lid loss will also not occur for a direct-loaded RH waste container with a welded lid, or the Removable Lid Canister (RLC) for the RH-TRU 72-B cask. The RLC has a very robust lid- closure mechanism that uses grooved tabs (like the TRUPACT-II) and lock pins in lieu of bolting.4 However, a release via a breached lid closure or weld/container failure is assumed and is modeled similar to the SWB seal failure in item b. Except as noted in item f, overpacking a suspect metal drum of sound integrity within a larger vented metal drum, SWB, or RH canister can be credited to contain lid loss of the inner drum and prevent ejection of contents. If, however, a drum that does not meet the criteria in Table 4-2 is placed within a larger container, this configuration does not meet the definition of an overpacked container. In that case, since the inner drum does not meet the requirement for a container of sound integrity, the outer container is modeled as direct-loaded (see discussion in items a and b for SWBs). A significant release is not expected from overpacked suspect drums because the deflagration inside the inner drum is assumed to cause less damage to the outer overpack integrity than it would cause to a direct-loaded SWB as modeled in items a and b. A more limited release from potential venting through the outer container is assumed to occur in this case. For contaminated combustible waste, the release is modeled as an internal container fire with a confined burning ARF×RF of 5E-4, as noted in Sections 4.3.3 and 4.4.2 and Table 4-8. It is coupled, however, with a 0.2 DR for the outer drum overpack, as discussed in Section 4.3.3.3, Fire Damage Ratios for Other Containers. The deflagration release is therefore reduced by a factor of five (DR×ARF×RF = 1E-4) compared to the direct-loaded case discussed in item b. Note that the 0.2 DR is not applicable to highly energetic chemical reactions or similar container over-pressure events (i.e., events greater than about 50 psig release) where the outer overpack integrity may be compromised. For drums overpacked in a much larger container (e.g., a 55-gallon drum in a 110-gallon overpack), there may be enough free volume for the internal container to suffer lid loss and waste ejection within the outer overpack container. This condition requires enough free head space and enough free annular space for the lid to be displaced so that waste could be ejected from the inner 4 See the latest WIPP procedure for more information. DOE-STD-5506-2021 37 drum into the annular space between the drums. Absent analysis of a specific configuration, a conservative criterion of at least 8 inches of both free head space and free annular space is required for this phenomenon to occur. The outer container lid would be expected to remain in place. This event would be similar to item e, but it would involve an additional impact source term since material can eject from the inner container.

For contaminated combustible waste, the release is modeled as impact followed by fire. Impact release is based on the low-energy mechanical insult ARF×RF of 1E-4 noted in Section 4.3.3.1 and Table 4-8, for free-fall spill and shock-vibration stress and is applied to the 40% ejected from the experiment described above for a hydrogen deflagration in a direct-loaded drum). All of the material suspended from free-fall spill and shock-vibration inside the outer drum is not expected to be released via the seal and filter failures from the deflagration and overpressure; therefore, a factor-of-two reduction in the damage ratio is believed to be a conservative estimate, because two metal containers should provide some added protection; this results in an impact DR×ARF×RF of 2E-5 (0.5 × 40% × 1E-4). The release from a subsequent fire is modeled as the confined burning of the 60% inside the inner drum and the 40% ejected into the outer container with an ARF×RF of 5E-4 as noted in Sections 4.3.3 and 4.4.2 and Table 4-8; however, it is coupled with a 0.2 DR for the outer drum overpack, as discussed in item e above; this results in a fire DR×ARF×RF of 1E-4 (0.2 × 5E-4). The sum of these two releases results in an overall effective DR×ARF×RF of 1.2E-4. For the Pipe Overpack Container (POC), pressure testing showed that even if a hydrogen deflagration should occur, its magnitude would not be enough to damage the pipe component or significantly degrade its sintered stainless steel filter. See APPENDIX B, Section B.2.8, Other Waste-Container Considerations, for discussion of: (1) explosion tests performed by the Sandia National Laboratories (SNL 1998b) on the pipe component with a 1-inch sintered stainless steel filter; (2) hydrostatic pressure testing performed by Hauser Laboratories (Schierloh, 1998); and (3) a calculation that confirms the integrity of the pipe component for postulated internal explosion scenarios that evaluated pressures from a deflagration, detonation, DDT (deflagration-to detonation transition), and reflected wave effects (SRR 2011). See Section B.2.9, Deflagration Testing for CH Payload Containers and Filter Vents at Southwest Research Institute, regarding the Sandia National Laboratories explosion tests and the Hauser laboratories pressure tests (i.e., short-duration pressure bursts to simulate internal explosions) that demonstrated the integrity of a sintered stainless steel filter and O-ring seal to withstand high pressures. If the pipe component does not have a sintered stainless steel filter, then a release should be evaluated similar to item b above based on the form of material and seal failure of the 55-gallon POC lid. For fiberglass reinforced wooden boxes of uncharacterized TRU wastes, the Idaho test results discussed in APPENDIX B concluded that sufficient hydrogen buildup is not possible due to its lack of leak-tightness. For other containers, specific analyses are required to credit their ability to prevent lid loss and/or ejection of materials. 38 DOE-STD-5506-2021 4.3.3 Fire Scenario Damage Ratios for TRU Waste Containers This section addresses selection of DRs for fires involving TRU waste container storage for the facility DSA. The technical bases for the DR values presented in this section, including conservative assumptions where direct experimental data are not available, are included in APPENDIX C, Damage Ratios for Container Insults and Fires.

The most common TRU waste storage container is the open-top, 55-gallon steel drum with a bolted lid- locking ring, a DOT Type A container 5. Other drum sizes may include 15-gallon, 30-gallon, 35-gallon, 85-gallon, and 100-gallon. Waste may also be stored in SWBs, TDOPs, SLB2s, special-purpose containers, and in some unique cases, DOT Type B containers. In this section, drums are the primary focus, because they are bounding with respect to vulnerability to release. The term ñdrumò as used in this section means that it is a metal container of sound integrity as described in Section 4.3.1, so that it provides a confinement safety function. Although SWB and other bolted-lid container lids are bolted in place and are not expected to be lost, they are evaluated for releases from seal failure. This section also addresses overpacked containers (e.g., a metal drum of sound integrity nested within a larger metal drum or a SWB, TDOP, or SLB2), CCOs, and POCs. The RH canister is also evaluated for lid loss (direct-loaded) and seal failure (overpacked drums); as is the SCA which is used to permit handling RH waste as CH waste. Drum storage areas include rooms within buildings, transportainers, and domed structures, as well as staging or storage outdoors. Fires may also occur in drum loading and unloading areas for transportation. For fire scenarios involving multiple drums, pallets, pads, or the inventory of a building, the general approach is to estimate DRs based on estimating the footprint of the design-basis or evaluation-basis fire to determine the area of impact of the fire, including both direct flame contact and the radiant heat and heat fluxes. From this area and the storage characteristics, the number of drums that could be impacted is estimated. Assumptions are made with respect to drums stacked on top of each other, to determine how they fail (i.e., seal failure venting or lid loss due to a fire). The potential for lid loss and ejection of contents is also considered. For modeling drums exposed to flammable or combustible-liquid pool fires, an acceptable methodology is outlined in Chapter 65, ñLiquid Fuel Fires,ò of the SFPE Handbook of Fire Protection Engineering (SFPE 2016). That methodology can be used to establish fire-modeling inputs and assumptions to determine the number of drums involved, determine the extent of lid loss with ejected contents and seal failures, and to estimate the overall source term released. The following simplified approach for flammable or combustible-liquid pool fires and for ordinary combustible fires has been conservatively established to determine the extent of lid loss with ejection vs. seal failures and appropriate DRs for the different ARFs and RFs. Other site-specific fire modeling 5 Type A and Type B refer to the robustness of the drums, as defined by meeting a series of tests (drop, fire, water, etc.) specified by the DOT and the Nuclear Regulatory Commission. Type B is the more robust of the two, because Type B containers are required to survive a 30-min. fire and 30-ft drop test. Type A containers have no requirements regarding fires and survive only a 4-ft drop. 39 DOE-STD-5506-2021 approaches, based on drum-fire testing results, may be applied if technically justified and appropriately conservative for development of the control set.

Drums Exposed by Flammable/Combustible Liquid Pool Fires Fire calculations to support the DSA analysis are typically needed to determine the size of a pool fire and the extent of sufficient radiant heat flux (for pool fires and non-pool fires), which in turn are used to define the number of drums involved. These calculations shall be consistent with standard fire protection engineering methods for the bounding type of fires associated with the facility. DSA and FHA modeling assumptions (e.g., pool burning characteristics and depth of an unconfined pool) should be consistent unless justified for the different objectives of the analyses (i.e., DSA unmitigated scenario versus a FHA Maximum Possible Fire Loss scenario). The facility FHA should serve as the basic input to the DSA fire scenario development and any fire analysis performed to support the DSA. As directed by DOE O 420.1C, Chg. 2, Facility Safety, the FHA “… must be integrated into safety basis documentation.” Integration of the FHA and DSA can be achieved through various approaches, the primary objective being the consistency of similar fire analyses, credited controls, and conclusions. Additional guidance for integration of the FHA and DSA is provided in Section 4.2.2 (Fire Analysis) of DOE-HDBK-1224-2018 and Appendix B (Fire Hazard Analysis) of DOE-STD-1066-2016, Fire Protection. Two types of liquid-pool fires should be considered: • Unconfined crash/instantaneous spill fires, and • Confined spill fires if a means to contain liquid fuel exists Additionally, unconfined continuously flowing (also called metered leak) spill fires should be considered if the FHA identifies a specific facility target of concern in an area where significant liquid fuel sources are allowed to be present. All fuel sources should be considered, consistent with the facility FHA evaluation of significant quantities that could affect TRU waste containers. However, the most likely liquid fuel sources present in TRU waste facilities (hydraulic fluid and diesel fuel) are those present on TRU waste handling vehicles (forklifts, pallet movers, transport trucks, etc.). Though less common inside facilities, gasoline may also be a potential liquid fuel source, particularly for external fire events. General analysis aspects, applicable to all types of spill fires are summarized here; additional information is provided in APPENDIX C: • It is common practice to model a pool fire as a right circular cylinder centered on the vehicle involved. • The spill surface (where containers are located) should be taken as flat and level (not inclined) unless the slope is protected as a credited control in the safety basis. • The spill area (footprint) should not be adjusted for objects (pallets, drums, etc.) within the pool periphery. However, physical constraints such as curbs and room boundaries should be considered if present. Large depressions, ditches, or pits should be treated as a confined pool fire with defined pool fire boundaries. DOE-STD-5506-2021 40 • A liquid reservoir/tank constructed of metal should consider that some amount of the fuel would not likely be available to contribute to the pool fire diameter (i.e., a derated volume).

• The largest single flammable/combustible derated liquid tank capacity on each vehicle (i.e., one tank per vehicle) involved in the event should be considered as contributing to the footprint of a postulated pool fire unless it is plausible (based on proximity or the nature of the event) for more than one tank per vehicle to be breached by the same impact. However, given the short duration of the instantaneous spill fire, only the single largest tank should be considered where a breach is postulated due to fire propagation. It is not plausible to consider fire-induced breach of multiple tanks at or near the same time in a manner that would combine their volumes when determining a conservative pool fire footprint. Where different fuels are involved (e.g., diesel fuel and hydraulic fluid), the tank that presents the highest ST should be used. As a rule of thumb (all else being equal), the pool fire which can only cause seal failure would need to involve more than about twice the number of drums to match the consequences of a pool fire that causes both lid ejection and seal failure. See APPENDIX C for more information. An overview of an acceptable methodology is provided here for: • modeling the unconfined crash/instantaneous and metered leak spill fires, • modeling the involvement of vehicle tires in the metered leak spill fire, • calculating critical incident flux to containers remote from the fire, and • assessing pool fire damage to standard TRU waste containers. The technical bases and derivation of the methodologies used are presented more fully in APPENDIX C and Pool Fire Analysis Methodology for Assessing Damage to Waste Containers (SRNS 2020). Container damage estimates, including potential lid ejection, should be consistent with those described below unless otherwise justified. Modeling the Unconfined Crash/Instantaneous Spill Fire The unconfined crash/instantaneous spill fire should be modeled as having a 2.9-mm spill depth as specified in the SFPE Handbook (SFPE 2016) when combined with other conservative aspects of pool fire modeling outlined in APPENDIX C. For most liquid hydrocarbon fuels, a 2.9-mm-deep pool fire will burn for approximately 70 to 120 seconds, a range that falls within the minimum time frame required for either lid ejection (~70 seconds) or seal failure (~120 seconds) damage to a standard TRU waste container. The 15-to-20-second duration of the more-likely 0.7-mm-deep unconfined fuel spill is too short to cause damage to any standard TRU waste containers and should be considered only where damage to a thermally sensitive target (e.g. nearby combustibles) is identified as a concern by the fire scenario in the facility FHA. Modeling the Unconfined Metered Leak Spill Fire The unconfined metered-leak spill fire need not be considered for assessing direct damage to TRU waste containers because it is always bounded by the unconfined crash/instantaneous spill fire. However, where the facility FHA identifies a target with a thermal stress failure threshold longer than about 120 to 300 seconds, the metered-leak spill fire should be evaluated. For those scenarios, such as failure of a structural 41 DOE-STD-5506-2021 steel support column or fire rated containment features (e.g., Type B shipping packages), the spill area should evaluate a spill rate that obtains the target failure threshold based on either fire duration or fire diameter (typically target engulfment). If the metered-leak spill fire results in a fire lasting about 10 minutes or longer, the vehicle tires would likely have an opportunity to influence the pool diameter and should be included, as described next.

Modeling Tire Involvement in the Unconfined Metered Leak Spill Fire Empirical testing of dual truck tires (SINTEF 1995) indicates that the pool size formed by the molten tires is maximized in about 10 minutes. The SINTEF testing is used (SRNS 2020) to derive a conservative estimate of the tire fire footprint based on dimensions and combustible mass of the burning tire(s). The modeling approach combines the footprint of the liquid metered-leak pool fire involving at least one tire set on the vehicle. If the spill rate, tire parameters, and ignition timings are known, a steady-state spill diameter can be determined based on equations 65.26a and 65.26b or, for very large spill rates (150–600 gpm), equations 65.27a and 65.27b, from SFPE 2016. Modeling the Confined Spill Fire Fuel spill into a confined area should be evaluated based on the geometry of the scenario. A postulated confined-spill pool fire should be modeled the same as an unconfined pool fire described above, except that the footprint is based on the size of the confined area and that a pool fire lasting longer than about 120 seconds is more likely to result in seal failure damage. A longer-duration pool fire (as might be expected for a confined spill) should apply an increased DR for seal failure (up to 1.0) regardless of the population, if the fire duration is expected to exceed about 120 seconds. Otherwise, a confined-spill pool fire does not alter the drum damage estimates described for unconfined pool fires. Though tire involvement is possible, it would not increase the pool size and doesn’t need to be considered for the confined spill fire. However, if the fire is of sufficient duration to result in pallet collapse and drum toppling, additional damage associated with material spill and unconfined burning shall be evaluated. See Appendix C for additional detail. Calculating Critical Flux to Containers Remote from the Fire Critical flux is that necessary to cause seal failure in a TRU waste container remote from the postulated fire and has been defined, based on Kaiser-Hill 2000, as when at least one-third of the container is exposed to a heat flux exceeding 15.9 kW/m2. Insight from evaluation of these reports along with recent POC and TRU waste drum testing results (SNL 2018a and, SNL 2018b) suggests another seal failure criterion of 45 kW/m2 at the point on the surface of the container that is nearest to and directly facing the fire. In the more recent testing at SNL, the flux gauges were positioned beside (not attached to) the containers that experienced seal failure. In that configuration, it is expected that they would receive additional convective and radiative losses on the back side, thereby increasing the level of radiative heat flux measured. As discussed in APPENDIX C, a seal failure criterion of 40 kW/m2 in lieu of the suggested 45 kW/m2 for the point on the surface of the container nearest to and pointing directly at the fire, is determined to be more appropriate and a better analytical fit as well as being slightly more conservative. 42 DOE-STD-5506-2021 Critical flux is defined as having all three elements specified in Table 4-4, Critical Flux Criteria Required to Obtain Seal Failure. Table 4-4. Critical Flux Criteria Required to Obtain Seal Failure Incident flux should be calculated using the detailed Shokri and Beyler method outlined in Chapter 65 of the SFPE Handbook (SFPE 2016). 6

Either of the critical flux criteria specified above may be used to evaluate seal-failure damage to waste containers. A comparison of the standoff/separation distance required to avoid seal failure using each of the two criteria for instantaneous crash/spill pool fires indicates they are within about 10% of each other for pool fires up to about 7.0 m (23 ft) in diameter (APPENDIX C , SRNS 2020). Given the approximations and conservatisms used in developing these methodologies, either the 40 kW/m2 or the 15.9 kW/m2 criterion is considered appropriate for use. There is no need or intent to require a large set of sensitivity tests to choose the most bounding approach for every variation to be considered. The analyst should select the approach most analytically appropriate to the particular set of fire scenarios being evaluated, develop a technical basis for the methodology or methodologies employed, and apply that approach and that basis consistently. Use of an analysis method other than the detailed Shokri & Beyler method for assessing damage to TRU waste containers should be supported by adequate technical basis. Direct Pool Fire Damage to TRU Waste Containers Based on fire testing of drums, fires can cause release of radioactive and other hazardous materials from metal containers in three ways; these are characterized as “Seal Failure, “Lid Rupture,” and “Lid Loss”: • Seal Failure. Fires can cause lid seals to fail (seal failure), allowing unfiltered outgassing at the interface between the lid and body of the container. Seal failure is defined as degradation of the container seal (gasket), warping of the lid from its retaining ring, or failure of the container filter or filter media, concurrent with ignition and burning of combustible container contents, all of which are subject to the confined burning ARF 5E-4 with a 1.0 RF, as discussed in Sections 4.3.3.2 and 4.4.2. • Lid Rupture. Fires can cause warping of the lid from its retaining ring but not complete ejection of the lid. Two other similar failure mechanisms are separation of the bottom seam of a drum and “fish-mouth” tears in the side of a drum that result in an opening size similar to a warped lid and are included in this category. A lid rupture is similar to a lid loss except that the overpressure is not 6 See APPENDIX C for additional information on acceptable heat-flux calculation methods. DOE-STD-5506-2021 43 sufficient to completely separate the lid from its retaining ring and waste is not ejected. This occurs in a relatively short period of time (e.g., less than ~3 minutes) that is the same as when lid loss occurs; however, a difference is that lid rupture usually results in a torch-like flame of the combustion gases around the breached lid seal occurring over an extended period of time as the waste continues to burn. For lid ruptures from pool fires and exposures fires involving contaminated combustible and noncombustible solid wastes, they are included in the evaluation of seal failures that are subject to the confined burning ARF 5E-4 with a 1.0 RF, as discussed in Sections 4.3.3.2 and 4.4.2. However, for powder-like wastes, ejection of material may occur and the release depends on the rupture pressure of the waste container and combustibility of the waste, as discussed later in this section.

• Lid Loss. Fires can cause the lid to be forcefully ejected (lid loss), possibly with an accompanying ejection of material from within the container. Ejected materials are subject to the unconfined burning ARF of 1E-2 with a 1.0 RF, as discussed in Section 4.4.2. Notwithstanding the recommendation in Section 4.3.2 regarding unconfined burning of a fraction of the ejected wastes from a drum deflagration, all wastes ejected are assumed to burn unconfined due to the external fire source. All materials remaining in drums with lid loss are subject to the confined burning ARF of 5E-4 with a 1.0 RF, as discussed in Section 4.4.2. Since the different drum responses involving confined and unconfined burning result in significantly different estimates of airborne releases, damage ratios need to be addressed for both situations. To simplify the modeling approach, drum contents are modeled in this section as 100% combustible contaminated solid wastes. Evaluation of direct pool fire damage to TRU waste containers with bulk powders is discussed below in the section Direct Pool Fire Damage to TRU Waste Containers. Lid Loss Lid loss can occur only if specific conditions associated with an engulfing deep pool fire are met (e.g., a “fast” fire growth rate, “rapid” flame spread rate, direct flame impingement, or sufficient duration). Engulfing deep pool fires are those fires in which burning liquid fuel surrounds the container, is capable of gas-phase or rapid liquid-phase flame spread 7, and is capable of sustaining engulfing fire conditions in excess of 70 seconds. These fires can cause lid loss to a fraction of the engulfed drums, which may eject a portion of the contents. From the fire testing experience described in APPENDIX C, not all unrestrained drums engulfed in a pool fire experienced lid loss. By conservative assumptions, 25% of the unrestrained drums8 engulfed in the pool fire experience lid loss and ejection of some contents, so the analytical model more accurately represents the results of the fire tests. This applies to the top tier of drums in a stacked pallet storage array and to all drums in a steel-rack storage array since the lids are unrestrained on each tier. Some unrestrained drums adjacent to the fire that have direct flame impingement (first-row-out) are also conservatively assumed to experience lid loss and ejection; therefore, apply the same 25% assumption. 7 The principal driver for flame spread is the temperature of spilled liquid relative to its flashpoint. See APPENDIX C. 8 It is noted that the test data indicates there is a higher propensity for lid ejection with drums dispersed or separated in a manner to permit thermally thick (~>1 ft) flame impingement over a significant portion (~> 75%) of the drum’s vertical surface. 44 DOE-STD-5506-2021 A container fully outside the periphery of the fire (i.e., exposed to no flame impingement) and not adjacent to an engulfed drum should not be considered a first-row-out drum. It should instead be considered a possible second-row-out drum subject to seal failure damage as determined below. If containers are stacked, the drums on the lower tiers are expected to retain their lids, as the weight of the upper tiers will keep them in place or, at worst, result in partial lid displacement. These containers should also be considered to receive seal failure damage as described below. For modeling purposes, it is sufficient to assume that lid loss occurs only on the top tier, and some contents are ejected, as determined next. If the potential exists for a long duration pool fire, see the discussion on Modeling the Confined Spill Fire .

For drums that experience lid loss, one-third of the contents (33%) 9 are assumed to be ejected from the drum. During the ejection, this material is subject to shock-vibration stress due to its ejection and impact with a hard surface plus burning as unconfined materials. The other two-thirds (67%) of the MAR are assumed to stay inside the drum and burn as confined materials. The DR is 1.0 for each portion, or this could be thought of as a DR of 0.33 of the total MAR for the ejected portion and 0.67 for the remainder in the drum. Seal Failure Container seal failure should be evaluated as possible from any of three damage mechanisms: • Direct flame impingement (engulfed or along the edge of the pool but not experiencing lid loss) • Proximity to drums experiencing lid loss (second-row-out drums) • Sufficient radiant heating (critical flux) Assessing Pool Fire Damage to Waste Containers As stated above, container seal failure damage is modeled as 100% confined burning of combustible materials for any of the three possible damage mechanisms. If a container on the top tier in the second row outside the pool area (second-row-out) is adjacent to a drum in the first-row-out along the edge of the pool fire that loses its lid, seal failure is also expected due to the likely magnitude of radiant heat flux from the open drum fire and lack of shielding from the first row. The number of second-row-out drums with seal failure should be the same as the number of first-row-out drums with lid ejection. Drums on lower tiers in the second-row-out below the top tier do not experience seal failures due to assumed shielding from the first row of lower-tier drums, which do not experience lid loss, and the limited “view factor” from any flame. Containers remote from the pool fire but near enough that they can receive critical radiant flux as identified in Table 4-4 above, also experience seal failure damage with confined burning of the contents. From a DSA analysis perspective, this is modeled the same as container exposure from an ordinary combustible fire and is addressed in Section 4.3.3.2. Determination of containers damaged in a postulated waste material handling vehicle pool fire is best determined graphically, as illustrated as a scaled diagram in Figure 4-1, Example Graphic Assessment of 9 See APPENDIX C discussion regarding how conservative this assumption is. 45 DOE-STD-5506-2021 Pool Fire Damage. Those drums fully engulfed are depicted with a designator “A.” Although the test data indicates the drum need to be fully engulfed, the example diagram adds minor conservatism by including drums that are more than half engulfed. The first-row-out drums are depicted the letter “B.” Drums in the second-row-out which can potentially receive seal failure damage are labeled “CC.” The number of drums in the second-row-out that are actually given seal failure damage is calculated as described above, thus their depiction is not actually necessary. Drums near enough and unobstructed enough to receive critical incident flux are colored yellow, to show seal failure, and labeled “C.” The diagram also provides a count of the top tier of drums determined to receive each level of pool-fire damage. Figure 4-1. Example Graphic Assessment of Pool Fire Damage

Direct Pool Fire Damage of Powder-filled TRU Waste Containers The response of a TRU waste container in a pool fire predominately filled with finely divided wastes (e.g., bulk powders of oxides or salts, organic absorbents or dry organic sludges; hereafter referred to as powders) would be bounded if modeled the same as a container filled with combustible waste with respect to the number of drums receiving lid ejection, lid rupture, or seal failure. However, for consequence assessment, a release associated with these phenomena would be better characterized as a pressurized release commensurate with the container’s release pressure and a DR of 1.0. Pressurization of a TRU waste container that is assessed to receive lid ejection, lid rupture, or seal failure from the fire should be treated as a powder container overpressure as described in Section 4.4.1, Deflagration and Overpressure Events, and modeled as a pressurized release at ≤ 25 psig, with an ARF of 5E-3 and 0.4 RF 0 ft. 3 ft. 5 ft. 10 ft. 8'-6" B A A A A A B A A A A A A A A A A A B CC CC B A A B CC CC CC CC B C B A Pool Fire for this scenario (16.4 ft dia.) Standoff distance for this scenario (18.6 ft dia.) Drum engulfed in pool Drum in first row out from pool Drum within standoff distance and with ≥ 120° exposure Drum in second row out from pool (Number involved is calculated)CC LEGEND B B CC B B B CC B CC CC CC CC CC CC CC A A A A C CC CC B A CC B CC CC B A B A CC CC B A C CC B A B C 26 18 2 Top Tier Drum Damage Count 46 DOE-STD-5506-2021 (ARF×RF = 2E-3). No significant amount of powder is expected to be expelled from the container for lid loss or lid rupture due to this low overpressure, and especially if there is interior packaging if metal convenience containers are used. Similar to the discussion in Section 4.4.1, no guidance is provided if a waste process generates a finely-divided combustible waste (such as organic absorbents or dry organic sludge that behaves like a powder) directly loaded into a standard waste container, which warrants an evaluation based on the unique properties of the waste and type of container involved in the pool fire. If the FHA or other fire modeling for the DSA evaluates a hazard associated with a very long duration pool fire (much greater than the 3 minutes required for lid loss, lid rupture, or seal failures), noncombustible powders could contribute additional thermal stress to the portions remaining in the drum after depressurization (i.e., 1 – ARF of 5E-3 = 99.5%). However, this could only occur if the pool fire lasts long enough to heat all the mass of remaining powder. If analysis of pool fire duration and noncombustible powder mass indicates it is possible, the thermal stress release with ARF = 6E-3 and RF = 0.01 should be added to the pressurized release. The 6E-5 ARF×RF thermal contribution is added to the 2E-3 pressurized release, resulting in a composite ARF×RF of 2.06E-3, rounded to 2.1E-3. For any of these release mechanisms, application of a 1.0 DR introduces significant conservatism because only the top few inches of powder would be expected to participate in the release. It is also noted that rupture mechanisms postulated to occur below the top surface of the powder mass (i.e., those related to a “fish-mouth” tear on the side of the container or separation at the bottom seam) are not plausible in a powder-filled drum due to the heat sink presented by the oxide, salt, or noncombustible matrix itself, based on insights from the SNL testing of pipe component containers with an oxide simulant (SNL 2020). Additional technical bases for these release fractions are presented in Section 4.4.1 on deflagrations/over- pressurizations and Section 4.4.2 on fires.

Other Spill Fire Considerations Hydraulic fluid pool fires10 should be treated differently from other hydrocarbon liquid fuels (e.g., diesel fuel). Because of the high flashpoint of typical hydraulic fluids, flame spread beyond the point of ignition is very unlikely. However, in the presence of a significant long-duration ignition source (such as a burning TRU waste-handling vehicle), heating of the liquid above its flash point is possible. In this case, liquid- phase flame spread is the only plausible mechanism that would permit the greater part of the hydraulic fluid spill to become involved in the fire. Flame spread would not approach the bounding liquid-phase flame spread rate presented in literature. Based on this, unconfined hydraulic fluid spills fires are not considered capable of creating rapid heating conditions necessary to cause lid ejection in exposed standard TRU waste drums. Although the slow propagation could enhance the possibility of seal failure damage, the depth of the unconfined pool will limit the fire duration to less than about 90 seconds. As described below, seal failure requires significant heat flux for longer than about 120 seconds. Given that engulfing pool fire conditions expose most of a container’s surface to high incident flux, it is not reasonable to conclude there is no seal failure damage. A conservative approximation considers that seal failure damage in an unconfined hydraulic fluid spill pool fire occurs on 50% (DR = 0.5) of the containers engulfed, in the first-row-out, or subjected to critical incident flux (Table 4-4). The population is inclusive 10 A pressurized spray of hydraulic fluid is not a spill. However, it presents an easily ignitable flame jet hazard to nearby objects or containers that should be considered. Though severe in nature, the consequences of flame jet impingement on a few TRU waste containers is typically bounded by the consequences of the pool fire modeled, as described here. DOE-STD-5506-2021 47 of all containers assessed to receive seal failure damage. This DR should not be applied for a small population of containers (i.e., for < 10 containers based on consistency with Section 4.3.3.2 for seal failures due to exceeding critical incident flux, assume a DR of 1.0). The following summarizes the above discussions. See APPENDIX C for additional detail. Unconfined Flammable/Combustible Fuel Spill on Hard, Smooth, Flat Surface 11 • Unconfined fuel spills pool to a depth of 2.9 mm. • Fuel spills of hydraulic fluid do not cause lid ejection of a TRU waste drum. • Lid ejection damage to a standard TRU waste drum occurs only when the drum experiences engulfing, or near-engulfing flame conditions, with a rapid heat-up profile and occurs within about 70 to 90 seconds. • Seal failure damage to a standard TRU waste container is possible when the container is exposed to lid-ejection damage conditions but doesn’t experience lid ejection, or when the container receives critical incident flux, or greater, for longer than about 60 seconds.

This approach does not consider toppling of stacked drums and potential for additional unconfined burning of scattered wastes. Rapid pressurization is not expected to topple higher-tier drums based on the Idaho hydrogen deflagration experiment described in Section 4.3.2. The Hanford fire tests did not observe toppling. The drums, however, were banded to pallets that allowed the drums to slump vertically. Failure of metal pallets is much less likely and would require a sufficiently long-duration fire to cause failure, not typically associated with potential unconfined spill fires in TRU waste storage areas, and shall only be evaluated in the DSA if the potential exists for a long duration pool fire (see discussion on Modeling the Confined Spill Fire) or it is evaluated for the Fire Hazards Analysis based on the fixed and transient fuel loading associated with TRU waste operations. However, a fire would be expected to cause toppling of stacked drums on combustible (e.g., wooden or plastic) pallets, which shall be evaluated if this hazard exists at a site. Further, combustible pallets would be expected to participate in the fire, resulting in potentially increased fire severity heat release rate and lengthened fire duration. Figure 4-2, Fire Damage Ratios (DRs) for Direct-Loaded Drums, illustrates the foregoing approach to estimate the source term from a pool fire. It also summarizes the approach to calculate non-pool fire source terms as presented in the next section. The term “DR” is used to reflect the different fractions of MAR that are affected differently—e.g., ejected waste vs remaining waste in the drum, or involvement of 10 or more drums to radiant heat exposure. 11 Hard and smooth indicates surface is generally non-porous and smooth to include bare concrete, coated concrete, brushed concrete, tile, and steel. Flat indicates a lack of surface depressions >~5 mm in depth. If the spill occurs on a surface that is not paved and smooth, use actual surface characteristics for analysis. DOE-STD-5506-2021 48 Ordinary combustible fire Determine # drums within critical heat flux (see Table 4.3.3-1) Determine # drums inside pool (MAR) Determine # drums 2nd row outside pool (MAR) Define Design or Evaluation Basis Fire DOE-STD-5506-2021 Fire Hazard Analysis or Documented Safety Analysis fire modeling Lose lids on 25% of top tier drums 0.25 DR Lid not ejected on 75% of top tier drums 0.75 DR plus 100% of lower tier drums 1.0 DR Eject 1/3 contents Source term from confined burning: 0.25x0.67 DR, 5E-4 ARF, 1.0 RF Source term from ejection and impact: 0.25x0.33 DR, 1E-3 ARF, 0.1 RF Source term from unconfined burning: 0.25x0.33 DR, 1E-2 ARF, 1.0 RF Source term from 2nd row drums same # (MAR) as 1st row drums that ejected contents: 1.0 DR, 5E-4 ARF, 1.0 RF Source term from < 10 drums (MAR): 1.0 DR, 5E-4 ARF, 1.0 RF Source term from ≥ 10 drums (MAR): 0.5 DR, 5E-4 ARF, 1.0 RF Unconfined Spill 2.9 mm deep Source term from < 10 drums (MAR): 1.0 DR, 5E-4 ARF, 1.0 RF Source term from ≥ 10 drums (MAR): 0.5 DRb, 5E-4 ARF, 1.0 RF Flammable or combustible liquid pool firea Determine # drums inside pool area (MAR) Non-hydraulic fluid pool fire a. Drums remote from pool: determine # of drums within critical flux same as ordinary combustible fire. b. DR = 1.0 for confined spill pool fires lasting longer than ~120 sec. Hydraulic fluid pool fire 2/3 contents remain in drum Determine # drums 1st row outside pool

(MAR) Combine (MAR) Source term from seal failure (Top tier: 0.75 DR + Lower tier(s): 1.0 DR) 5E-4 ARF, 1.0 RF Figure 4-2. Fire Damage Ratios (DRs) for Direct-Loaded Drums 49 DOE-STD-5506-2021 Drums Exposed by Ordinary Combustible Fires Non-pool fires are those that involve ordinary combustibles such as trash, wooden boxes, or clothing. This type of fire has a “moderate” fire growth rate. Fire experiments have demonstrated that lid loss and ejection of contents is not expected, so for modeling purposes, only seal failures are evaluated. This could include trash fires and wooden crate fires. For direct flame impingement on only one side of a container from an adjacent ordinary combustible fire, the container is not heated rapidly enough to cause lid loss and ejection of contents. When heat transfer occurs only through radiation, fires involving non-liquid fuel packages (e.g., trash) were determined to not result in lid loss. The heat output of the fire is insufficient to increase temperature and pressure inside the drum quickly enough to eject the lid before venting (seal failure) occurs. The container has to be close enough to the fire that it is exposed to a sufficient heat flux (Table 4-4). To simplify the modeling approach, drum contents are assumed to be 100% combustible contaminated solid wastes. DOE does not have an experimentally-derived release fraction (ARF×RF) for seal failure of metal drums caused by ordinary combustible fires. DOE has chosen to apply the ARF×RF value of 5E-4 from DOE Handbook 3010 to such drums in a waste fire example in its Section 7.3.9.1, “Hazard Summary” (of Section 7.3.9, Solid Waste Handling). This value is based on experiments involving cardboard cartons burned in a large steel tank. The tank was provided with passive ventilation openings at the top and bottom, which would support development of a buoyancy-driven chimney effect to enhance burning as compared to a TRU waste drum with a small opening only at the top of the container (seal degradation or vent filter opening). A correction factor of 0.5 is intended to account for differences between cartons and metal drums. Specifically, this damage ratio is used because DOE expects a lower degree of combustion/ pyrolysis (and thus aerosol generation) within an unventilated steel drum, compared to the cardboard carton in a large steel tank from the experiments. It has been estimated that 50% of the combustible material burned in the tests with the cardboard cartons (Mishima 2001). In contrast, experiments with metal drums suggest that 25% of drum contents will burn or pyrolyze (Mishima 2001), although mass losses from pool fires with no lid ejection have a wide range from all of the fire drum tests. Thus, a correction factor of 0.5 is used to account for the difference between cartons and drums. This correction factor includes an assumption that the generation of radioactive aerosols (ARF) is directly proportional to the mass of combustibles consumed by the fire. There are various reasons why this assumption would not hold, including the possibility that the radioactive material was not uniformly distributed throughout the combustible waste. A fire could preferentially burn the more contaminated portions of the waste, in which case ARF would not be proportional to mass loss.

To account for the possibility of a non-uniform distribution, DOE has decided not to apply the correction factor for events with less than 10 drums. With 10 or more drums, it is unlikely that the fire would only consume the most contaminated portion of the waste within every drum. Thus, the correction factor can be applied for events involving ten or more drums. 12 12 See Section C.1.3, Seal Failures, for additional discussion of a 0.5 DR for 10 or more drums. 50 DOE-STD-5506-2021 If room flashover is deemed plausible by the FHA or other fire modeling for the DSA unmitigated analysis, then all containers are subject to seal failures with a 1.0 DR. Another type of fire that could cause a lid loss occurs when flammable/combustible liquid is present in the drum with other combustible solid wastes. A fire involving any type of fuel package may result in auto-ignition of flammable vapors inside the drum. For these mixed combustible wastes, based on assuming small amounts of the liquid, this phenomenon is modeled in accordance with assumptions presented in Section 4.3.2, unless otherwise justified. The Section 4.3.2 hydrogen deflagration modeling assumptions do not apply to drums of mixed wastes of combustible solid wastes with flammable or combustible liquids that exceed the small-quantity VOC assumption as described in APPENDIX B, Container Deflagrations, or drums of radioactive flammable or combustible liquids. For combustible solid wastes with large quantities of VOCs (e.g., where the VOC quantity exceeds the WIPP WAC requirement that observable free liquid is less than 1 percent by volume of the outermost container at the time of radiography or visual examination, or the equivalent amount of absorbed liquids), a DR of 1.0 is conservatively assumed for ejection of combustible wastes and unconfined burning because of the lack of experimental data and the uncertainty about what can occur under these conditions. If the contents are radioactive flammable or combustible liquids and have no combustible solid wastes, the release is modeled per recommendations in the DOE-HDBK-3010-94, assuming a DR of 1.0 for lid loss and subsequent burning of the liquid inside or outside the drum. It should also be noted that the Hanford fire tests concluded that an internal fire in a single drum is not expected to propagate to an adjacent drum 13, whether the adjacent drum is to the side or above the drum with the internal fire. 14 Fire Damage Ratios for Other Containers A similar DR for seal failures of SWBs is established based on physical consideration that four drums are approximately equivalent to one SWB. This results in a DR of 0.5 for more than two SWBs involved in a fire (i.e., 10 drums divided by 4 and rounded up). However, a DR of 1.0 is assumed for one or two SWBs involved in the fire.

Overpacking a metal drum of sound integrity with a larger metal drum, an SWB, or a TDOP, can be credited to prevent lid loss and ejection of contents and modeled as seal failures. In addition to preventing lid loss, overpacked containers provide an additional level of protection from fires that allows a lower DR of 0.2 than those for directed-loaded drums or SWBs. The dimensions of the SWB are nominally 5 ft long, 4 ft wide, and 3 ft tall, with rounded sides to fit within the TRUPACT-II container for shipments to WIPP. The walls are typically 10-gauge to 12-gauge (about 0.1-in.) sheet metal, and the container is sealed with a gasket and lid with 42 bolts. The TDOP is constructed in a manner similar to a SWB and provides primary confinement to a large drum-like volume that can be loaded directly or as an overpack for 10 full 55-gallon drums, up to 6 full 85-gallon drums, or an SWB. Both the outer container and inner drums in an overpack assembly have vents installed in order to meet the requirements for an overpack assembly. For a radioactive material release to occur, the fire has to heat up the inside of the SWB/TDOP and also heat the inner contents of the 55-gallon drums resulting in pyrolization of the drum contents and subsequent venting from both containers. The SWB/TDOP configuration presents a significant heat sink 13 Fire Protection Guide for Waste Drum Storage Arrays, WHC-SD-SQA-ANAL-501 14 The heat generated by a fire within a drum and possible “torches” via seal failure were not significant enough to heat adjacent drums to cause their failure. This is different than the sympathetic deflagration discussed in Section 4.3.2. 51 DOE-STD-5506-2021 and pyrolization of drum contents would require a very long-lasting fire or a very large fire. Another consideration is that the SWB/TDOP is large, and therefore it is not expected that all of the waste will be affected by a fire. Although the drum-in-drum overpack does not provide the same level of heat sink, the overpacked drum fire testing described in Section B.2.4, Volatile Organic Compounds, reported the results of the 1993 LLNL test of 3-drum and 4-drum configurations in a 6-foot pool fire. The LLNL test involved the drums inside the pool fire, which is the basis for the 0.2 DR that was estimated from the average 0.1 mass loss for direct-loaded drums to the average 0.025 mass loss for the overpacked drums based on the data presented in Table B-12. Therefore, a DR of 0.2 is assumed for overpacked drums of sound integrity whether overpacked in a larger drum, a SWB, or a TDOP. This assumption applies to a single or multiple overpacked containers exposed to the radiant heat flux that causes seal failures and to overpacked drums in a pool fire. Also, DRs presented in this section for “overpacked containers” are based on having two containers of sound integrity and do not apply to overpacked drums where the inner drum is not of sound integrity (Table 4-2), which is modeled as a single, direct-loaded drum. Direct-loaded RH canisters may experience lid loss depending on the design of the lid restraint, because it is only required to be qualified as a DOT Type A container. As discussed in Section 4.3.2 for hydrogen deflagrations within a RH canister, lid loss will not occur for a direct-loaded RH container whose lid is welded, or the RLC for the RH-TRU 72-B cask. Although RH canisters with nested drums are expected to behave in a manner similar to SWBs and not experience lid loss, the SWB DRs above can be applied to overpacked RH drums in a canister. For RH canisters or drums handled outside a hot cell facility in a shielded “facility cask” or onsite shipping cask that does not meet the DOT Type B criteria 15, lower DRs may be appropriate. This can be justified based on a fire hazards analysis or DSA fire modeling to assess the extent of damage for bounding facility-specific fires or material-handling equipment fuel spills 16.

In the case of POCs and CCOs, the containers are designed in a manner that precludes their failure during expected storage area fires. Four POCs were subjected to Type B protocol thermal tests as summarized in APPENDIX C. The associated 150-MW fuel pool fire caused the one outer 55-gallon drum of a POC package with a metal filter to experience lid loss 17. This occurred within the first 3 minutes of the fire. Post-fire inspection showed the pipe component seal and filter gasket to be damaged. Associated leak rate testing of this POC showed a total leak rate of 24 cm3/s at a differential pressure of 87 kPa. This leak rate was later associated with an ARF of 6E-6 for the bounding material type in POCs (i.e., powder) 18. It should be noted that inspection of the POC packages remaining intact revealed that the POCs did not experience temperatures above 200 °F and remained leak-tight. Similar results were observed in a series of more recent POC and CCO pool fire tests conducted at Sandia National Laboratories with combustible materials (POC only) and surrogate oxide payloads as 15 Casks that meet current Type B criteria normally are expected to survive facility fires typical of those that may occur in the DOE Complex where TRU wastes are stored or handled, unless a facility-specific hazard or accident can cause a mechanical breach of the cask or a much longer duration of fire is possible. 16 For example, see Damage Assessment of Waste Containers Involved in Accidents at the Waste Isolation Pilot Plant, PLG- 1121. 17 The other POC packages had plastic filter seals, which melted during the fire. 18 See Section C.1.4.1, Initial Pipe Overpack Container Fire Testing, discussion. 52 DOE-STD-5506-2021 summarized in APPENDIX C (SNL 2017, SNL 2018a, SNL 2018b, SNL 2019, and SNL 2020). The POC test results support a conclusion that as long as the drum lid remains on the outer 55-gallon drum of the POC (even with seal degradation), the fiberboard insulation inside protects the inner pipe component. Maximum temperatures within the inner pipe component do not exceed 176 °F (80 °C), a temperature that does not threaten ordinary combustibles placed in the pipe. After tests where lid ejection did not occur, the filter gasket and O-ring of the pipe component were found to remain pristine. Use of the engineered UltraTech 9424S filter (Patent Pending), a special modification to the previous WIPP-approved UltraTech 9424 filter, prevents loss of the outer drum lid. The 9424S filter thereby ensures that the protective fiberboard insulation remains in place, though charring does occur. For Safety Basis purposes, POCs that have the UltraTech 9424S filter installed per manufacturer’s specifications in the outer 55-gallon drum’s ¾-inch lid opening can be assigned a DR of zero, irrespective of whether they contain residues, particulates, combustibles, or any other waste form in an authorized configuration for scenarios bounded by the evaluated test conditions. POCs may be loaded with ordinary combustible material only if the outer 55-gallon drum is equipped with the UltraTech 9424S filter. This Standard does not provide guidance on modeling releases of ordinary combustible waste in a POC that lacks the UltraTech 9424S filter or a PC that contains flammable or combustible liquids with flash points less than 100° C without a sintered filter. Potential deflagrations in a POC are further discussed in Sections B.2.8, Other Waste-Container Considerations, and B.2.9, Deflagration Testing for CH Payload Containers and Filter Vents at Southwest Research Institute.

CCO testing did not include combustible materials inside the pipe component (criticality control container, CCC) except for minor combustible packaging materials (small bags and tape). The most recent testing (SNL 2020) of a CCO loaded with surrogate oxide packaged in a can–bag–can configuration inside the CCC documents that the inner bag and pieces of tape on the outer slip lid can were consumed in the fully engulfing 30-minute pool fire. The outer drum lid and upper plywood dunnage were ejected early in the test, exposing the top of the CCC to flame temperatures of ~1200 °C, which damaged the CCC lid filter. The report concludes: The above result suggests the ARF for CCO fully engulfed in a thirty- minute fire is zero. However, this conclusion is only accurate to the level of uncertainty of the mass balance used to measure the average mass of the powder before and after the test. Certainly, it can be argued that some material was released from the primary canisters into the secondary canisters, and subsequently into the CCC. It is important to note that the plastic enclosing the primary canister melted much later and well after the peak pressure of 18 psig was reached inside the CCC. Thus, it can be concluded with certainty that no aerosol release occurred before the melting temperature of the plastic was reached. When the plastic melted, the CCC reached a momentary internal pressure of about 2 psig, followed by a slow decay in pressure. It is not known if these lower pressures are sufficient to cause release of aerosol first from inside the primary canister, then from the secondary canister, and finally from the CCC through the damaged filter. Posttest examination of the secondary canisters suggest their lids appear to remain in place throughout the test, 53 DOE-STD-5506-2021 implying the above sequence of events leading to release of aerosol from secondary canisters in highly unlikely. The torturous path from the primary container through the secondary container and then out of the CCC supports the conclusion for the down blend powder a DR of zero is appropriate and is further supported by the fact that no powder was observed anywhere outside of the primary container. Therefore, POCs or CCOs without combustibles in the inner pipe component (except incidental bags and tape used for packaging) involved in storage and room fires need not be further evaluated in an accident analysis. POCs may be loaded with combustible material only if the outer 55-gallon drum is equipped with the UltraTech 9424S filter installed per manufacturer’s specifications. CCOs loaded with combustible material should be analyzed with a DR=1.0. This Standard does not provide guidance on modeling releases of combustible waste in CCOs. A lower DR may be used if payload materials have unique waste form properties or cause unique behaviors in the container response to postulated thermal stresses, as long as explicit technical justification is provided for the lower value.

4.3.4 Damage Ratios for Mechanical Insults This section addresses DRs for the steel drums of various sizes (e.g., 55-gallon, 85-gallon, and 100- gallon), SWBs, RH canisters, POCs, and overpacked containers (e.g., a 55-gallon drum of sound integrity nested within an 85-gallon drum, or four drums in a SWB; the TDOP; or an RH canister with nested drums). Several tests have been performed for dropping 55-gallon drums from various heights and with various weights and contents, and for crushing drums. These are described in APPENDIX C, Damage Ratios for Container Insults and Fires. However, there has been no testing of the SWBs with “bolted down” lids, overpacked containers, or the TRUPACT-II double-stacked seven-pack drum configuration. Therefore, engineering judgment was applied to extrapolate the available test results to these configuration and accident scenarios. The term “drum” as used in this section means that it is a metal container of sound integrity as described in Section 4.3.1, so that it provides a confinement safety function. DRs presented in this section for “overpacked containers” do not apply to drums that are not of sound integrity, which shall be modeled as a single, direct-loaded drum. Drops and impact stresses on TRU waste containers will result in a wide range of damage depending on the magnitude of these forces and condition of containers. Loss of confinement from a TRU waste container can result from severe shock and vibration stress, from impact events or dropping a container. Spills from a container can also result from the accidental falling or flowing of powders out of a confinement boundary resulting in an airborne release due to the free-fall of the powder in air. As stated in Section 4.3, the DR is that portion of the MAR that is affected by the accident stresses. For TRU waste containers, the materials are primarily contaminated combustible or noncombustible solid materials, solidified/vitrified sludges that do not contain free liquids, or powders of radioactive compounds. The term “loss of confinement” as used in this section refers to the hazard and accident analysis loss of confinement/containment categories as listed in Table 3-1, and may result in low-energy or high-energy mechanical insults to containers as discussed in Section 4.4.3, Mechanical Insults. Containers may be punctured, crushed, toppled, or dropped, causing failure of the container and release of the material. Dispersal of the material will occur from the kinetic energy from the accident initiator and from the 54 DOE-STD-5506-2021 fall of material from the container failure point to the ground. In the case of container failure due to corrosion, the energy for dispersal is provided by the fall of the material from the container failure point to the ground. Significant release of non-dispersible wastes, such as those that have been vitrified or solidified with concrete in metal containers, would require higher energy input to release the wastes than is available from mechanically initiated spills, such as spills caused by container punctures, drops, or falls.

Examples of potential spill scenarios may include a spill from a metal container following a forklift puncture or impact by a compressed gas cylinder missile; a spill of waste container(s) due to drops/falls; or a spill of waste container(s) resulting from impact with material-handling equipment. Based on the Sandia, Hanford, and Rocky Flats experimental results of drum testing, each of these accident types is addressed in APPENDIX C to establish a range of DRs for various container types and waste forms. From this range of damages, DRs are established for other drop or impact events that can breach waste containers associated with heights typical of existing facilities in the DOE Complex that store and handle TRU wastes. Six broad categories were chosen to represent the range of damage ratios. Appropriate adjustments are made if the material form is contaminated solids (e.g., “bulkier materials” larger pieces, such as filters, or pieces of wood and metal, or contaminated combustible waste) versus sand-like material that may be free-flowing, as well as vitrified waste forms. An overview of APPENDIX C insights from drum and metal-box testing performed by Sandia National Laboratories, Hanford, and Rocky Flats follows. A majority of the reported drum tests were performed with DOT Type 17C drums with a rigid polyethylene liner containing bagged waste of various forms. However, generators will also ship drums that currently have the designation of Type 17H (thinner wall), and both types of drums will be shipped with and without liners. The type of drum and the presence of a liner within it cannot be readily distinguished once it is packaged. Type 17C drums are made from 16-gauge material, which has a nominal wall thickness of 0.059 inch. The Type 17H drums are made from 18-gauge material, which has a typical wall thickness of 0.039 inch. Based on simple calculations of compression stress in the wall and axial buckling performed in the PLG-1121 report, Type 17C drums are stronger than the Type 17H drums. Because both types of drums are to be handled and stored, the characterization of drum failure should be based on the more limiting case of Type 17H drums. DOT Type A drums are only qualified for a 4-ft drop as discussed in Section 4.3.1. Drum drop testing and static axial crush tests indicated that they perform very well, but results are significantly affected by impact orientation and weight of the contents, among other variables. For example, no lid failures (and thus, no material releases) occurred for drop heights less than 44 ft (13 m) or impact velocities less than ~35 mph for the heaviest drum tested of 748 lb. However, all 1,000-lb drums landing such that the lid locking ring bolt struck the test surface failed at a drop height of 11 ft (3.4 m). Obvious (highly visible) damage to a drum is not necessarily an indicator of drum integrity. Extensive damage to the drum walls may not be indicative of container breach, whereas a small amount of damage to the lid and upper sealing surface may cause lid separation and loss of container integrity. The testing concluded that drum deformation cannot be predicted by considering only the kinetic energy of the system; drum contents, too, are important because different materials absorb various amounts of energy. The DRs are based on the amount of spillage of sand-like materials (powders) from test results increased to account for shock- vibration effects that could suspend particulates; a factor of two reduction is assumed for contaminated bulkier materials.

55 DOE-STD-5506-2021 The SWBs are made from 10-gauge material (minimum thickness approximately 0.128 inch) and have a bolted lid. Because there are no tests for the SWBs, some insight is available from the results of the Rocky Flats DOT 7A welded-metal-box drop tests. There was no apparent failure of seams or closure welds and no contents were lost from either waste box for the 15-ft drop. For the 25-ft drop test, a pinhole leak was detected. Since the SWB uses a bolted lid and gasket configuration, its performance should be similar to the welded box. However, there is a lack of direct test data; the container is only required to meet the DOT Type A drop test for 4 ft; and it has a much larger load capacity (4,000 lb). For these reasons, DRs for drops are established based on those for the 55-gallon drum. This is also based on simple compression stress in the wall and axial buckling calculation performed in the PLG-1121 report. The report concluded that Type 17C drums appear to be stronger than the SWBs, which in turn are stronger than the Type 17H drums. However, the lids for the SWBs are bolted to the body of the container, implying that lid separation is much less likely for the SWBs than for the drums. DRs for forklift punctures are reduced by a factor of two, recognizing the much larger size of the container, as discussed in APPENDIX C, and for the accident involving falls equivalent to a fourth tier of drums (about 10 feet). The RH waste canister for a 72-B shipping cask is a 0.25-inch-thick carbon steel cylindrical vessel having an outside diameter of 26 inches and an overall length of 121 inches. Standard vessel heads are welded to each end of the cylinder, or the top may have a mechanical lid such as the RLC described in Section 4.3.2. They are designed to DOT Type A criteria. It is reasonable to assume that their performance during drop and impact events would be at least as good as the performance of SWBs. Therefore, the SWB DR recommendations apply to spill events involving RH waste canisters. This is also supported by structural calculations in PLG- 1305, Remote Handled Transuranic Waste Container (RH-TWC) Structural Analyses for Postulated Handling Accidents. For RH canisters or drums handled outside a hot-cell facility in a shielded “facility cask” or onsite shipping cask that does not meet the DOT Type B criteria19, lower DRs may be appropriate. This can be justified based on quantitative or qualitative arguments to credit the more robust container. For overpacked containers, no test data are available. For the single-package drop event, a factor-of-two reduction in the damage ratio is believed to be a conservative estimate, because two metal containers should provide some added protection for drop events. This applies to containers of sound integrity overpacked in another container of sound integrity, e.g., a 55-gallon drum of sound integrity nested within an 85-gallon drum, or four drums in a SWB; the TDOP; or an RH canister with nested drums. It does not apply to overpacked containers that do not meet the Section 4.3.1 criteria. The TRUPACT II payload configuration is a two seven-pack plastic-wrapped drum configuration. Based on the pallet drop testing discussed in Section C.2.2.2, Palletized Drum Falls, a DR of 0.2 for sand-like materials and 0.1 for bulkier contaminated items is recommended for a crane drop of the two 7-pack wrapped drum configuration. The overall DRs include an adjustment for the type of contents, an adjustment which is based on test data for maximum spillage for two drums and average spillage for the other five drums. In addition, the overall DRs round up to account for other shock-vibration effects and for conservatism.

The POC consists of a sealed pipe component (Schedule 40 pipe with a 6-inch diameter or Schedule 20 pipe with a 12-inch diameter), contained within a Type 17C 55-gallon drum. The pipe component is 19 Casks that meet current Type B criteria normally are expected to survive facility mechanical insults typical of those that may occur in the DOE Complex where TRU wastes are stored or handled, unless a facility-specific hazard or accident is more severe than the testing requirements. 56 DOE-STD-5506-2021 separated from the drum by fiberboard packing material and a plastic liner. The lids of both the drum and the pipe component have filtered vents. The robustness of the POC was assessed by Rocky Flats 20 based on data taken from reports of Type B protocol testing conducted at the Sandia National Laboratories (e.g., crush, 30-ft drop, and 30-min. fire tests), pressure tests, and finite-element computer modeling of crushing and puncturing. Rocky Flats concluded that the POC does not qualify as a DOT Type B container, for two reasons: (a) it was not subjected to the complete Type B protocol testing program, and (b) the pipe component is vented. However, the tests that were performed were passed, and it is expected that the puncture test would also have been passed, based on computer modeling and comparison with similar containers that are certified as Type B. The POC far surpassed the DOT Type A test requirements. For spill scenarios, POCs are vulnerable only to drops/falls from a distance of greater than 30 ft, structural collapse of substantial construction facilities (where falling structural concrete slabs impact POCs such as seismic collapse addressed in Section 4.3.5, Natural Phenomena Damage Ratios for TRU Waste Container Storage), and puncture by forklift tines. Stacked POCs could be toppled following a forklift collision. The POCs would be expected to withstand the impact associated with the toppling of stacks of POCs, because the distance to fall is less than that in the Type B drop tests: a five-high drum-stacking configuration means that the top drum would fall a distance equal to the height of four drums plus the pallet separatorsðabout 13 ft altogether, less than half the distance used in the drop test. Due to the fiberboard material (CelotexÈ) fill in the POC, the robust design of the Schedule 20 or 40 inner pipe, and the POC drop test performance, no release is expected from a cylinder missile impact. The POC was determined by finite-element modeling to be vulnerable to the forklift tine puncture due to the chisel design assumption and very small impact area. A forklift tine puncture of a POC may cause a localized rapid release of powder material from a pipe component if the POC can be pinned against an unyielding surface. The likelihood that a POC will be punctured by a forklift is ñExtremely Unlikely,ò as discussed in Section C.2.1.4, Pipe Overpack Container Testing for Accidents Other Than Fires. Most of the conditions described in Appendix C are applicable to all the sites except conditions 1 and 2 described in APPENDIX C may be different for each site. The frequency qualitatively determined in APPENDIX C is ñBeyond Extremely Unlikelyò but is conservatively assumed to be ñExtremely Unlikelyò for the forklift tine puncture of POC. Regarding NPH-generated missiles impacting POCs, DOE-STD-1020-2016, Natural Phenomena Hazards Design and Evaluation Criteria for Department of Energy Facilities, establishes design basis wind/tornado missile criteria for design of new facilities and evaluation of existing facilities. These NPH design basis missiles do not have a small impact area/chisel design similar to a forklift tine; therefore, no release is expected from a wind/tornado design-basis missile impact. Other missiles could be generated from a hig