DOE-STD-5002-2017, Disposal Authorization Statement and Tank Closure Documentation

DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Not Measurement Sensitive DOE-STD-5002-2017 May 2017 DOE STANDARD DISPOSAL AUTHORIZATION STATEMENT AND TANK CLOSURE DOCUMENTATION U.S. DEPARTMENT OF ENERGY WASHINGTON, D.C. 20585 This document is available on the U.S. Department of Energy Technical Standards Program Web Site at: http://energy.gov/ehss/services/nuclear-safety/department-energy-technical-standards- program/doe-approved-technical DOE-STD-5002-2017 http://energy.gov/ehss/services/nuclear-safety/department-energy-technical-standards-program/doe-approved-technical http://energy.gov/ehss/services/nuclear-safety/department-energy-technical-standards-program/doe-approved-technical i TABLE OF CONTENTS ACRONYMS AND ABBREVIATIONS ................................................................................... xii FOREWORD................................................................................................................................. 1 GUIDING PRINCIPLES ............................................................................................................. 3 CHAPTER 1. INTRODUCTION & PURPOSE ..................................................................... 1-1 CHAPTER 2. PERFORMANCE ASSESSMENT GUIDE .................................................... 2-1 DOE-STD-5002-2017 ii 2.2.2.6.1 Performance Objectives ............................................................................... 2-13 2.2.2.6.2 Point of Assessment and Timing Assumptions ............................................ 2-20 2.2.2.7.1 ALARA Analysis ......................................................................................... 2-33 2.2.2.7.2 Other Requirements ..................................................................................... 2-36 2.2.3.1.1 Geography and Demographics, Populations, Use of Adjacent Lands ......... 2-43 2.2.3.1.2 Meteorology and Climatology ..................................................................... 2-44 2.2.3.1.3 Ecology ........................................................................................................ 2-44 2.2.3.1.4 Geology, Seismology, and Volcanology ..................................................... 2-44 2.2.3.1.5 Hydrology .................................................................................................... 2-45 2.2.3.1.6 Geochemistry ............................................................................................... 2-45 2.2.3.1.7 Natural Resources ........................................................................................ 2-46 2.2.3.1.8 Natural Background Radiation .................................................................... 2-46 2.2.3.3.1 Waste Characteristics for Screening ............................................................ 2-54 2.2.3.3.2 Radionuclide Inventory Screening for Water and Air Pathways ................. 2-54 2.2.3.3.3 Radionuclide Inventories for Further Analysis ............................................ 2-54 2.2.4.2.1 Source Term Release ................................................................................... 2-67 2.2.4.2.2 Radionuclide Transport ................................................................................ 2-70 2.2.4.2.3 Exposure Pathways and Scenarios ............................................................... 2-73 DOE-STD-5002-2017 iii

Attachment 2.1. Example Structure for Systems Evaluation .......................................................... 2-129 CHAPTER 3. COMPOSITE ANALYSIS GUIDE ................................................................. 3-1 3.2.2.2.1 Performance Measures ................................................................................... 3-7 3.2.2.2.2 Points of Assessment and Compliance Period ............................................... 3-8 3.2.3.4.1 Radionuclide Screening Approach............................................................... 3-21 3.2.3.4.2 Graded Approach to Source Term Screening .............................................. 3-21 DOE-STD-5002-2017 iv 3.2.4.2.1 Source Term Release ................................................................................... 3-43 3.2.4.2.2 Radionuclide Transport ................................................................................ 3-43 Attachment 3.1. Example Options Analysis Outline........................................................................... 3-81 CHAPTER 4. CLOSURE PLAN GUIDE ................................................................................ 4-1 DOE-STD-5002-2017 v CHAPTER 5. PA/CA MONITORING PLAN GUIDE .......................................................... 5-1 DOE-STD-5002-2017 vi CHAPTER 6. WASTE ACCEPTANCE CRITERIA GUIDE ............................................... 6-1 CHAPTER 7. PA/CA MAINTENACE PLAN GUIDE .......................................................... 7-1 DOE-STD-5002-2017 vii CHAPTER 8. CHANGE CONTROL PROCESS GUIDE ..................................................... 8-1 Attachment 8.1. Example of Unreviewed Disposal Question Screening Criteria ............................ 8-15 Attachment 8.2. Example of Unreviewed Disposal Question Evaluation ......................................... 8-17 Attachment 8.3. Example of Unreviewed Composite Analysis Question Screening Criteria ......... 8-19 Attachment 8.4. Example of Unreviewed Composite Analysis Question Evaluation ...................... 8-21 Attachment 8.5. USQ/UDQE/SA Integrated Process Flowchart ....................................................... 8-23 CHAPTER 9. DISPOSAL FACILITY ANNUAL SUMMARY REPORT GUIDE ............ 9-1 DOE-STD-5002-2017 viii Attachment 9.1. Example Annual Summary Report Cover Letter ................................................... 9-25 DOE-STD-5002-2017 ix LIST OF FIGURES AND TABLES Figure 1-1. Components of the Safety Case, Including On-going Interactions with Interested Parties and Regulators (IAEA 2012) .................................................................................. 1-6 Figure 1-2. Contributors to Defense-in-Depth in DOE’s Integrated Systems Approach for Safe Disposal of Radioactive Waste ........................................................................................... 1-7 Figure 1-3. Disposal Authorization Statement Development, Review/Approval Flowchart............... 1-20 Figure 2-1. Example of Evolution of Performance of a Disposal Facility Over Time .......................... 2-9 Figure 2-2. Example of a Distribution of the Probability of Inadvertent Intrusion ............................. 2-32 Figure 2-3. General Guidance for Determining the Level of ALARA Analysis Required ................. 2-35 Figure 2-4. Example Design Features Associated with a Tank Closure PA Required ........................ 2-51

Figure 2-5. Example Illustration of Summary Inventory Information for a Disposal Facility ............ 2-56 Figure 2-6. Example of a Conceptual Model of Shallow Land Burial ................................................ 2-59 Figure 2-7. Transport Pathways Considered for a Disposal Facility ................................................... 2-60 Figure 2-8. Example Showing Different Modeling Components and Features Considered for Tank Closure PA ............................................................................................................... 2-61 Figure 2-9. Example Exposure Pathways for a PA ............................................................................. 2-74 Figure 2-10. Example Illustration of Different Exposure Scenarios for a PA ....................................... 2-75 Figure 2-12. Example Elements of the Models Implemented for a Tank Closure PA .......................... 2-82 Figure 2-13. Example of Benchmarking Concentrations from a 3D Model with a 1D Abstraction of the 3D Model ................................................................................................................ 2-84 Figure 2-14. Typical Figure Illustrating the Contribution of All Key Radionuclides to the Total Dose as a Function of Time .............................................................................................. 2-91 Figure 2-15. Example Graphic to Illustrate the Range of Results with the Deterministic Compliance Case Included for Comparison ..................................................................... 2-92 Figure 2-16. Examples of Different Approaches to Illustrate Sensitivity Analysis Results .................. 2-98 Figure 2-17. Example Illustrating Different Peaks that are Dominated by Different Radionuclides and thus will Have Different Drivers of the Sensitivity .................................................... 2-99 Figure 2-19. Example Exposure Scenarios from Intrusion Associated with Tank Closure at SRS to Address NRC Expectations......................................................................................... 2-104 Figure 3-1. Example Points of Assessment for Streams Discharging to the Savannah River at the Site Boundary (SRS CA) ............................................................................................ 3-12 Figure 3-2. Summary of Operating Areas and Types of Residual Contamination at a Site ................ 3-18 Figure 3-3. Mapping of Sources to Different Transport Pathways to the Receptors at the Points of Assessment ................................................................................................................... 3-19 Figure 3-5. Example 3 Phase Radionuclide Screening Approach with Third Step Using a Generally Accepted Risk Assessment Screening Model Used at the Site ........................ 3-23 Figure 3-6. Example Conceptual Model for Model-Based Radionuclide Inventory Screening .......... 3-25 DOE-STD-5002-2017 x Figure 3-7. Example Considering the Magnitude of Interactions as a Result of Dispersion Over Long Distances .................................................................................................................. 3-32 Figure 3-8. Example of Changing Interactions Over Time from NEPA Analysis Considering Potential Interactions to Support Siting of a Facility (Contours for 1/10th of the MCL)................................................................................................................................. 3-35

Figure 3-9. Example Flow Chart for Graded Approach to Consider Individual Sources .................... 3-41 Figure 3-10. Example General Conceptual Model for a Source ............................................................ 3-45 Figure 3-11. Example Summary of Pathways Considered in a CA ....................................................... 3-46 Figure 3-12. Example Illustration of the Models Selected for a CA and How They are Applied ......... 3-48 Figure 3-13. Example Showing 1D Path-Lines Derived from a 3D Flow Model Representing Transport from Individual Sources to Discharge Points in Different Streams ................. 3-52 Figure 3-14. Example Results Comparing Fluxes Obtained from a 3D Model with Fluxes Predicted Using an Abstraction to an 1D Equivalent Model and Illustrating Pessimistic Bias of the Simplified Model ......................................................................... 3-53 Figure 3-15. Example Figure Illustrating Projected Flux from the Source to the Vadose Zone Soil for a Source ................................................................................................................ 3-56 Figure 3-16. Example Showing the Results from Multiple PA Facilities Considered in a CA ............. 3-58 Figure 3-17. Example Figure Illustrating Projected Doses at Different Receptor Locations Considered in a CA ........................................................................................................... 3-59 Figure 3-18. Example Source Term-Specific Doses to Identify Key Contributors to Dose .................. 3-60 Figure 3-19. Example Illustrating the Range of Potential Results for Different Percentiles using a Probabilistic Approach ................................................................................................... 3-62 Figure 3-20. Example Considering Different Locations of the Site Boundary ..................................... 3-63 Figure 4-1. Aerial View of ERDF with Cells Used for Disposal .......................................................... 4-7 Figure 5-1. Example of Facility Description Schematic ........................................................................ 5-4 Figure 5-2. Site Characteristics .............................................................................................................. 5-7 Figure 5-3. Example of Ground Water Modeling Location Schematic ............................................... 5-11 Figure 5-4. Graded Approach in Response to Unexpected Performance Monitoring Data ................. 5-18 Table 1-1. Technical Basis Documents Review and Approval Responsibilities ................................ 1-12 Table 2-1. Example Summary of PA Results from a Disposal Facility ............................................... 2-4 Table 2-2. Example Default Exposure Scenarios, Performance Objectives and Measures, and Points of Assessment for the Performance........................................................................ 2-15 Table 2-3. Performance Assessment Review Criteria ...................................................................... 2-113 Table 3-1. Example Table with CA Results for the Executive Summary ............................................ 3-5 Table 3-2. Example Table Highlighting Changes in the Updated Version of a CA ............................ 3-6 Table 3-3. Composite Analysis Review Criteria ................................................................................ 3-72

Table 4-1. Compliance of the Performance Assessment with DOE O 435.1 ..................................... 4-14 DOE-STD-5002-2017 xi Table 4-2. Closure Plan Review Criteria ............................................................................................ 4-16 Table 5-1. Examples of the Two General Types of Monitoring .......................................................... 5-5 Table 5-2. Example Monitoring Summary ........................................................................................... 5-9 Table 5-3. Example of Ground Water Modeling Location Schematic ............................................... 5-15 Table 5-4. PA/CA Monitoring Plan Review Criteria ......................................................................... 5-20 Table 6-1. Radionuclide Action Levels for Waste Characterization and Reporting ............................ 6-5 Table 6-2. Review Criteria for Waste Acceptance Criteria ................................................................ 6-14 Table 7-1. Example: Secondary Issues Status Table ............................................................................ 7-7 Table 7-2. Example of Maintenance Plan Schedule of Activities ...................................................... 7-10 Table 7-3. Maintenance Plan Review Criteria ................................................................................... 7-15 Table 8-1. Change Control Process Review Criteria .......................................................................... 8-11 Table 8-2. Special Analysis Review Criteria ..................................................................................... 8-13 Table 9-1. Potential Changes Affecting the PA, CA, DAS OR RWMB .............................................. 9-4 Table 9-2. Examples of Conditions/Discoveries/New Information That Have the Potential to Affect the PA, CA, DAS or RWMB ............................................................................... 9-6 Table 9-3. Waste Receipts .................................................................................................................... 9-9 Table 9-4. Example of Waste Receipts .............................................................................................. 9-11 Table 9-5. Compliance Monitoring .................................................................................................... 9-11 Table 9-6. Performance Monitoring ................................................................................................... 9-12 Table 9-7. Examples of Compliance Monitoring ............................................................................... 9-13 Table 9-8. Examples of Performance Monitoring .............................................................................. 9-14 Table 9-9. Research and Development Activities .............................................................................. 9-15 Table 9-10. Example of Research and Development Activities ........................................................... 9-16 Table 9-11. Planned or Contemplated Changes ................................................................................... 9-17 Table 9-12. Example of Planned or Contemplated Changes ................................................................ 9-18 Table 9-13. Status of DAS Conditions, Key and Secondary Issues .................................................... 9-18

Table 9-14. Example of Status of DAS Conditions, Key and Secondary Issues................................. 9-19 Table 9-15. Annual Summary Report (ASR) Review Criteria ............................................................ 9-21 DOE-STD-5002-2017 xii ACRONYMS AND ABBREVIATIONS ALARA As Low As Reasonably Achievable ASR Annual Summary Report CA Composite Analyses CD Critical Decision CER Compliance Evaluation Report CERCLA Comprehensive Environmental Response, Compensation and Liability Act CFR Code of Federal Regulations CP Closure Plan CRD Contractor Requirements Document D&D Decontamination and Decommissioning DAS Disposal Authorization Statement DASWMM Deputy Assistant Secretary for Waste and Material Management Director DCFPAK Dose Coefficient File Package DNFSB Defense Nuclear Facilities Safety Board DRISE Director Regulatory Intergovernmental and Stakeholder Engagement DSA Documented Safety Analysis DOE U.S. Department of Energy DOT U.S. Department of Transportation EIS Environmental Impact Statement ELLWF E Area Low-Level Waste Facility EM DOE Office of Environmental Management EPA U.S. Environmental Protection Agency ERDF Environmental Restoration Disposal Facility FE Field Elements FEM Field Element Manager FEP Features, Events and Processes FFA Federal Facilities Agreement FFC Federal Facility Compliance FMB Four Mile Branch FUSRAP Formerly Utilized Sites Remedial Action Program G DOE Guide DOE-STD-5002-2017 xiii HLW High-Level Waste HQ Headquarters IAEA International Atomic Energy Agency ICRP International Commission for Radiological Protection LFRG Low-Level Waste Disposal Facility Federal Review Group LLW Low-Level Waste LTR Lower Three Run LLWDF Low-Level Waste Disposal Facility M DOE Manual MCEP Motor Carrier Evaluation Program MCL Maximum Contaminant Level MDA Material Disposal Area MEI Maximally Exposed Individual MLLW Mixed Low-Level Waste MonP Monitoring Plan MP Maintenance Plan NCRP National Council on Radiation Protection and Measurements NDAA National Defense Authorization Act NE DOE Office of Nuclear Energy NEA Nuclear Energy Agency NEPA National Environmental Policy Act NESHAP National Emissions Standards for Hazardous Air Pollutants NNSA National Nuclear Security Administration NORM Naturally Occurring Radioactive Material NPDES National Pollutant Discharge Elimination System NRC Nuclear Regulatory Commission NUREG NRC Regulatory Guides O DOE Order ODAS Operating DAS P DOE Policy PA Performance Assessment PARC PA/CA Review Committee PDAS Preliminary Disposal Authorization Statement DOE-STD-5002-2017 xiv PEIS Programmatic Environmental Impact Statement POA Point of Assessment PSO Program Secretarial Officers QA Quality Assurance QAP Quality Assurance Program R&D Research and Development RCRA Resource Conservation and Recovery Act ROD Record of Decision RWMB Radioactive Waste Management Basis SA Special Analysis SAR Safety Analysis Report SC Steel Creek SDF Saltstone Facility STD DOE Standard TED Total Effective Dose TENORM Technologically Enhanced Naturally Occurring Radioactive Material TRU Transuranic Waste UCAQE Unreviewed Composite Analysis Question Evaluation UCAQS Unreviewed Composite Analysis Question Screening UDQE Unreviewed Disposal Question Evaluation UDQS Unreviewed Disposal Question Screening WAC Waste Acceptance Criteria WIPP Waste Isolation Pilot Plant DOE-STD-5002-2017 1 FOREWORD

The Disposal Authorization Statement and Tank Closure Documentation Technical Standard is being issued to provide consolidated guidance for implementation of DOE Order (O) 435.1, Radioactive Waste Management. The document is based upon the original Low-Level Waste Federal Review Group guides that were issued shortly after issuance of DOE O 435.1 in 1999. Other text amplifies the guidance and includes examples, figures, and tables. Definitions of the various terms used in the Standard can be found in DOE Manual 435.1-1, Radioactive Waste Management Manual. Numerous elements of this Standard have already been implemented at multiple sites, including the sites located at Portsmouth, OH; Idaho Falls, ID; and Richland, WA, and utilized by the Low-Level Waste Federal Review Group to perform reviews of technical basis documentation. This U.S. Department of Energy Technical Standard is approved for use or reference by all Department of Energy Components and their contractors. Comments (e.g., recommendations, additions, and deletions) and any pertinent data and lessons learned that may improve this document should be sent to: Office of Regulatory Compliance U.S. Department of Energy Mailstop: EM-4.31 1000 Independence Ave., SW Washington, DC 20585 DOE-STD-5002-2017 2 DOE-STD-5002-2017 3 GUIDING PRINCIPLES The following guiding principles pertain to the application and provisions of this Technical Standard: The U.S. Department of Energy (DOE) meets its responsibilities regarding disposal of radioactive waste under the Atomic Energy Act of 1954, as amended, by providing the requirements for protection of the public, workers, and the environment for its radioactive waste disposal facilities in DOE Order (O) 435.1, Radioactive Waste Management. Requirements for protection of the public and environment from radiation are provided in DOE O 458.1, Radiation Protection of the Public and the Environment. DOE O 458.1, Section 4.h “Radioactive Waste and Spent Nuclear Fuel,” contains the requirements unique to management radioactive waste. DOE requirements for radiation protection of workers are provided in 10 Code of Federal Regulations (CFR) 835, Occupational Radiation Protection. DOE requirements for nuclear safety are provided in 10 CFR 830, Nuclear Safety Management. 1. DOE O 435.1 provides the specific requirements to the Federal and contractor entities throughout the DOE Complex that must be followed to ensure DOE is meeting its regulatory radioactive waste management responsibilities. This Standard provides the associated guidance to the Federal and contractor entities throughout the DOE Complex that should be followed to ensure DOE is meeting its regulatory radioactive waste management responsibilities. 2. DOE will ensure the disposal of radioactive waste is protective of the public, workers, and the environment through a documented process of technical and management reviews and approvals prior to any waste disposal. 3. DOE will continually evaluate the performance of the disposal facilities and update the associated technical evaluations and administrative documentation to the latest DOE requirements considering other regulatory and commercial entities practices. DOE-STD-5002-2017 4 DOE-STD-5002-2017 1-1 CHAPTER 1. INTRODUCTION & PURPOSE Introduction

The U.S. Department of Energy (DOE) including the National Nuclear Security Administration (NNSA) design, construct, operate, and close low-level waste (LLW)1 disposal facilities and conduct tank closures under the authority of the Atomic Energy Act of 1954, as amended, and in compliance with DOE Order (O) 435.1, Radioactive Waste Management, and guidance from this Standard. This Standard, when implemented by facility operators, will help assure that the technical basis for radioactive waste management disposal authorization is complete and sufficient. DOE has developed a systematic methodology using technical justification through site characterization, facility design, laboratory and field studies, mathematical modeling, technical analyses, and commitments to continuous improvement to demonstrate that the facility should be authorized to dispose of LLW. This process will result in DOE disposal facilities and tank closures that are protective of the public and the environment. This Standard provides a consistent approach for Federal and contractor personnel responsible for developing and/or reviewing documents that support the issuance of a Disposal Authorization Statement (DAS) and Tier 1 Closure Plans. The DAS provides Federal government authorization, not unlike a Nuclear Regulatory Commission (NRC) license or an U.S. Environmental Protection Agency (EPA) or State Regulatory permit, to authorize radioactive waste disposal. The DAS is issued by the appropriate DOE Headquarters (HQ) Program Secretarial Officers (PSO) including the NNSA Administrator responsible for the facility. This document details the overall DAS process, format and content of the DAS documents, and review criteria used in the development/evaluation of these documents. Applicability This Standard is applicable to the development, review and approval of documents that support the issuance of and revision to a DAS for the disposal of: LLW, mixed low-level waste (MLLW), transuranic waste (TRU)2 disposed onsite at DOE facilities other than the Waste Isolation Pilot Plant (WIPP), and Comprehensive Environmental Response, Comprehensive Environmental Response, Compensation and Liability Act of 1980 (CERCLA)3 waste at DOE 1 When this Standard refers to LLW or TRU, it also includes the hazardous component of the waste. 2 PAs prepared to address disposal of TRU waste should meet the requirements of 40 CFR Part 191, Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes. 3 Includes radioactive portion only. DOE-STD-5002-2017 1-2 disposal facilities. This Standard is applicable to government-owned, government-operated facilities in which DOE performs the function of the facility operator, as well as government- owned, contractor-operated facilities. This Standard applies to DOE and NNSA on-site disposal facilities and tank closure, whether regulated by DOE alone or in tandem with other regulators such as EPA, or state/local regulators. DOE regulates the radioactive waste portion of mixed LLW/TRU; the states and/or EPA have regulatory authority for waste under their purview. The approval to dispose of LLW is given by the appropriate PSO or NNSA Administrator that is responsible for the development and operation of the facility through the issuance of a DAS. The DAS is contractually enforceable under DOE requirements and Orders authorizing construction/operation of a LLW disposal facility. The DAS includes the design, construction, operational and closure requirements, conditions, and limitations that the disposal facility should meet to ensure continued protection of the public, and the environment.

To obtain a DAS, technical basis documents should be developed as described in this Standard, and as required by DOE O 435.1. A graded approach to developing technical basis documents should be chosen commensurate with the risks posed by any given facility. Purpose and Overview of the Standard This Standard identifies the documents required by DOE O 435.1 for DAS issuance or tank closure; the approval and issue process; and the maintenance and reporting requirements for a radioactive waste disposal facility. The Standard’s chapters are designed to be stand-alone documents, as each chapter refers to a separate technical basis document. In that regard, the Standard is a collection of technical basis documents to be referred to individually, and as needed. At a minimum, the technical basis documents necessary for a preliminary DAS (PDAS) include: • Performance Assessment (PA) (Chapter 2); • Composite Analysis4 (CA) (Chapter 3); and • Change Control Process (Chapter 8). At a minimum, the technical basis documents necessary for an Operating DAS (ODAS) include: • Performance Assessment (PA) (Chapter 2); 4 A final CA is not required; however, information showing compliance with the 100 mrem/yr performance measure and the effects of interacting sources must be available. DOE-STD-5002-2017 1-3 • Composite Analysis (CA) (Chapter 3); • Closure Plan (CP) (Chapter 4); • PA/CA Monitoring Plan (MonP) (Chapter 5); • Waste Acceptance Criteria (WAC) (Chapter 6); • PA/CA Maintenance Plan (MP) (Chapter 7); • Change Control Process (Chapter 8); and • Disposal Facility Annual Summary Report5 (ASR) (Chapter 9). At a minimum, the technical basis documents necessary for a Tier I Tank Closure include: • Performance Assessment (PA) (Chapter 2); • Composite Analysis (CA) (Chapter 3); • Closure Plan (CP) (Chapter 4); • PA/CA Monitoring Plan (MonP) (Chapter 5); • PA/CA Maintenance Plan (MP) (Chapter 7); and • Change Control Process (Chapter 8). This Standard and the Low-Level Waste Disposal Facility Federal Review Group (LFRG) Execution Plan (LFRG Execution Plan) supersede all the following documents: • LFRG Manual; • LFRG Program Management Plan; • LFRG Charter; • Format and Content Guide for DOE LLW Disposal Facility PA and CA; • Format and Content Guide for DOE LLW Facility CPs; and • Maintenance Guide for DOE LLW Disposal Facility PAs and CAs. The technical basis documents are presented as annotated outlines in the chapters of this Standard. The review criteria utilized by the Office of Environmental Management’s (EM’s) LFRG to evaluate the completeness and technical adequacy of technical basis documents are also included in this standard. These criteria are used to evaluate disposal facility performance and compliance. Modifications, deletions or additional review criteria for a specific disposal facility 5 An ASR will be prepared after the initial issuance of the DAS, at one year of operations, and every year thereafter. DOE-STD-5002-2017 1-4 review may be required based on site specific considerations. The criteria used for each review should be documented in the LFRG Review Plan and approved by the LFRG (see “Review Criteria” and “LFRG Review Process” for details of the review plan).

A PDAS should be approved by the responsible PSO prior to construction of a LLW disposal facility. Low-level waste disposal may also include mixed low-level waste (MLLW) regulated under Resource Conservation and Recovery Act (RCRA) and CERCLA disposal facilities. The technical basis documents should be prepared to inform the process of designing and constructing the disposal facility per DOE O 413.3B, Program & Project Management for the Acquisition of Capital Assets. The final approval of the documents that supports the resulting ODAS is not required until prior to the start of operation. The PDAS and ODAS are contractually enforceable under DOE regulations and orders [DOE O 435.1, Attachment 1, “Contractor Requirements Document” (CRD)] authorizing operation of a radioactive waste disposal facility. The PDAS and ODAS should be included in the Radioactive Waste Management Basis (RWMB). Successful PDAS and ODAS maintenance depends on the periodic review of the technical basis documents as new information (e.g., site characteristics, design, waste inventories, waste form, packaging) becomes available. Ensuring timely document revisions based on this enhanced understanding of the disposal system and operations is critical to compliance with DOE requirements. The annual summary review is an integral part of the DAS process and focuses on the changes of the current year’s performance and operations relative to the approved PA, CA and technical basis documents. It should describe the facility history and background information. The PDAS and ODAS compliance reviews may be initiated at any time by the LFRG, or other HQ organizations with responsibilities for line management or independent oversight of existing disposal facilities. For new facilities, compliance reviews should be completed before construction and operations of the facility begin. If any activities call into question the adequacy of an existing DAS, the LFRG, in collaboration with the LFRG site representative, should determine whether a revision is necessary and what that revision will contain. The LFRG will revise the PDAS or ODAS and present the draft to the DOE Office of Environmental Management (EM) PSO. The EM PSO will then present the PDAS or ODAS to the appropriate PSO disposal facility owner. A revision to either the PDAS or ODAS should be approved by the same PSO level of authority as the original. Integrated Protection Systems Approach for Safe Disposal of Radioactive Waste The guidance identified in this Standard reflects DOE-specific implementation of key parts of an integrated protection systems approach for safe disposal of radioactive waste. This also implements DOE’s version of the safety case for a disposal facility recommended by the International Atomic Energy Agency (IAEA) [e.g., IAEA Safety Glossary – Terminology Used in DOE-STD-5002-2017 1-5 Nuclear Safety and Radiation Protection (IAEA 2007); SSR-5, Disposal of Radioactive Waste, Specific Safety Requirements (IAEA 2012); and SSG-23, The Safety Case and Safety Assessment for the Disposal of Radioactive Waste (IAEA 2012)]. DOE does not invoke IAEA standards but uses the concepts identified in these standards to improve DOE’s radioactive waste management practices.

The IAEA publishes non-binding safety standards, including standards that address expectations for safe disposal of radioactive waste (SSR-5), as well as more detailed guidance for the development of a safety case and safety assessment (e.g., PA) (SSG-23). The IAEA safety standards provide general principles, but do not take the place of more specific national requirements. Similarly, the International Commission for Radiological Protection (ICRP) has produced recommendations related to radiation protection for radioactive waste disposal, and the National Council on Radiation Protection and Measurements (NCRP) published recommendations related to the development of PAs for disposal facilities [Radiation Protection Recommendations as Applied to the Disposal of Long-Lived Solid Radioactive Waste, International Commission for Radiological Protection (Publication 81, ICRP 1998)] (Performance Assessment of Near-Surface Facilities for Disposal of Low-Level Radioactive Waste (NRCP Report No. 152). This Standard represents the DOE-specific implementation of recommendations and standards for radioactive waste disposal and tank closure, especially related to expectations for a safety case for a disposal facility as described in the IAEA publications. Numerous references are made in the Standard to IAEA, ICRP, NCRP and other national and international standards and guidance as part of the basis for specific expectations. The safety case is generally defined as “A collection of arguments and evidence in support of the safety of a facility or activity. • This will normally include the findings of a safety assessment and a statement of confidence in these findings. • For a repository, the safety case may relate to a given stage of development. In such cases, the safety case should acknowledge the existence of any unresolved issues and should provide guidance for work to resolve these issues in future development stages” (IAEA 2007). The safety case concept provides a means to address, acknowledge, and document the factors that contribute to the safe disposal of radioactive waste. Figure 1-1 from the IAEA illustrates these components of the safety case at a high level (see IAEA 2012 for more details). Notably, the safety assessment, which includes operational safety analysis, PAs and other calculations, is only one part of the overall safety case for the disposal facility. The role of a PA as only one part of the overall case for safe disposal is a key consideration for the DOE integrated systems DOE-STD-5002-2017 1-6 approach to safety. This provides for defense-in-depth with multiple layers of safety features that leads to protection of human health and the environment. Figure 1-1. Components of the Safety Case, Including On-going Interactions with Interested Parties and Regulators (IAEA 2012) The technical basis documents introduced at the beginning of this chapter reflect a number of the layers of safety features that are part of the DOE approach in addition to requirements related to siting, design, waste characterization, operations, institutional controls, etc., that are included in DOE O 435.1. Figure 1-2 provides the contributors to the defense-in-depth approach that includes the following integrated safety features: • Natural and engineered barriers as part of the design of the total disposal system; • Rigorous assessments of facility performance (i.e. PA) and cumulative effects from other sources of radioactivity (i.e. CA) and use to refine the design and operations;

• RWMB, DASs, WAC, institutional controls; A. Safety case context B. Safety strategy C. System description D. Safety assessment G. Limits, controls and conditions H. Integration of safety arguments E. Ite ra tio n an d de sig n op tim iza tio n F.M anagem ent of uncertaintyIn vo lv em en t of in te re st ed p ar tie s an d th e re gu la to ry b od y DOE-STD-5002-2017 1-7 • On-going monitoring and maintenance activities, including field and laboratory studies, change control and modeling refinements to manage uncertainties in the PA/CA; and • Independent reviews of technical basis documents and annual operational reviews. Figure 1-2. Contributors to Defense-in-Depth in DOE’s Integrated Systems Approach for Safe Disposal of Radioactive Waste Low-Level Waste Disposal Facility Federal Review Group In order for a DAS or a Tier 1 Closure Plan to be issued, a review of the technical basis documents is required. EM, as the Office of primary responsibility for DOE O 435.1, leads the organization, LFRG, responsible for providing guidance and assistance, as well as regulatory oversight, to all DOE disposal facility operators. The LFRG provides regulatory oversight, identified in DOE Manual (M) 435.1-1, Radioactive Waste Management Manual, to confirm that DOE-STD-5002-2017 1-8 the disposal of low-level radioactive waste in DOE facilities and tank closures are conducted in a manner that is protective of public health and safety and the environment. A more detailed description of the LFRG membership, responsibilities, qualifications and process are contained in the LFRG Execution Plan. The LFRG is comprised of Federal employees from DOE HQ and Field Elements with radioactive waste disposal facility responsibilities and include: EM, Associate Under Secretary for Environment, Health, Safety, and Security (AU), NNSA, Office of Science (SC), and Office of Nuclear Energy (NE). The LFRG organization is led by Co-Chairs from the Office of Regulatory Intergovernmental & Stakeholder Programs, and the Office of Waste & Materials Management, within the Office of Regulatory and Policy Affairs. The LFRG process supports the DOE implementation of its regulatory responsibility under the Atomic Energy Act of 1954 as amended. The LFRG charters a technical review team comprised of Federal staff, site operating contractors, and consultant subject matter experts for DAS and tank closure technical basis document reviews. The results of the review are developed into a recommendation to the DOE PSO or NNSA Administrator. The recommendation may be to approve, approve with conditions, or disapprove technical basis documents. Review Criteria The LFRG review team conducts its review using the criteria established in this Standard. Each chapter of this Standard describes a specific basis document to be developed to technically justify the capabilities of a proposed or existing disposal facility or a tank closure. A description and annotated outlines are provided for the documents, as well as the review criteria. The review criteria provided in each chapter of the Standard are used by the LFRG review team and the LFRG at-large to evaluate the completeness and adequacy of the technical basis documents. The LFRG may choose to modify the list of criteria to be used in a certain review, based on the specific features of the disposal facility.

The criteria used for each review should be documented in a review plan and used to evaluate the associated document. The results of the review will be documented in a review report, and approved by the LFRG. A description of how the LFRG conducts its review and the responsibilities of the LFRG, LFRG review team, and other technical staff are described in the LFRG Execution Plan. Preliminary DAS and Operating DAS Prior to developing a new disposal facility, the Field site should initiate plans to comply with the requirements of DOE O 435.1 and implement the guidance of this Standard.6 Prior to 6 A disposal facility may consist of several units (e.g., trenches). It is not necessary for each unit to have a DAS. DOE-STD-5002-2017 1-9 construction of the disposal facility, a DAS should be approved. The DAS should at a minimum include the following DOE approved documents: PA, change control process, and an evaluation that shows the facility will meet the CA performance measure. The DAS provides a means where the site may proceed with construction of the facility at risk based upon a preliminary design and PA. Once the final design of the facility is completed, the PA will be reviewed by the site and LFRG to confirm that any changes to the parameters and assumptions have not significantly altered the conclusion regarding compliance with performance objectives/measures. If there is a significant change, the PA will be revised and reviewed again by the LFRG. There is no specific point in the project management process for initiating the approval for a DAS prior to Critical Decision (CD)-3, “Approve Start of Construction,” detailed in DOE O 413.3B. However, it is recommended that the DAS be approved once CD-3 is approved. DOE O 435.1 does not require a DAS be approved before construction begins. Prior to operating the disposal facility, an Operational DAS should be approved. Operational DAS should include the following DOE approved documents: PA, CA, MP, MonP, CP, WAC, change control process and ASR. The ASR is required after the first year of operations and every year thereafter. Based on the significance of the changes between PDAS documentation and the ODAS documentation, the LFRG should identify the scope of the review that is required to develop the ODAS. The Field site is expected to provide complete accounting of changes between the PDAS and the requested ODAS documentation, and finalize all required technical basis documents. During disposal facility operations, significant changes may occur from PA or CA assumptions, WAC, disposal practices, or new information may be discovered. While such changes are expected based on the newest information and captured through the “Change Control Process” (Chapter 8). A preponderance of changes is an indication that the DAS requires updating. The LFRG site member contacts the LFRG to inform them that a revision to the technical basis documents is being initiated. The site completes the appropriate update of the technical basis documents and notifies the LFRG that the revision is complete. The DAS and associated technical basis documents should be revised periodically but, at a minimum, every ten years from the initial issuance of the DAS. A five to 10-year schedule for DAS revisions will be developed by the LFRG. Proposed revision of these documents will be at the discretion of the site contractor, LFRG member, and/or LFRG at-large. The responsible PSO will determine if the DAS should be revised.

When the disposal facility is planning to cease operations, the DOE site is required to complete a final CP. Details of the closure process are included in “Closure Plan” (Chapter 4). The need to update the PA, CA and MonP should also be assessed at the end of operations. The PA/CA should demonstrate that the facility will be under active institutional control for the first 100 years following the end of operations (unless a longer period of control is demonstrated, justified DOE-STD-5002-2017 1-10 and approved by the LFRG) and complies with the performance objectives/measures within the 1,000-year timeframe required by DOE O 435.1. The Federal government expects to maintain continuous control of the disposal facility. Although continuous government control is required while a significant hazard is present, analyses should be completed to consider the potential consequences associated with hypothetical inadvertent intrusion into the facility during a temporary loss of institutional control. Tank Closure Tier 1 and Tier 2 Closure Plans are required for tank closures per DOE O 435.1 and the Ronald W. Reagan National Defense Authorization Act for Fiscal Year 2005, Public Law 108-375, October 28, 2004 [see NDAA Section 3116)7. This process is similar to the DAS process for disposal of radioactive waste. The recommended technical basis documents are found in “Purpose and Overview of the Standard.” DOE M 435.1-1, 4.b.(4) describes the requirements for the closure of deactivated high-level waste (HLW) facilities and sites. Deactivated HLW facilities should be closed in accordance with applicable state and Federal requirements and in accordance with the requirements of Section 4.a.(11), “Facility Closure.” Appropriate documentation should be developed for closure of deactivated facilities to describe the approach and plans by which closure is to be accomplished. Documentation should be completed and approved prior to the initiation of physical closure activities, and should include: a summary closure plan (Tier I) describing the planned approach for closing the deactivated HLW facilities; a PA; a CA; and a specific closure plan (Tier II) containing updated details on the closure activity, which supports final authorization to proceed with closure. The development of the PAs for the deactivation and closure of these facilities should be consistent with Chapter 2 of this Standard, and the review and approval of these PAs are the responsibility of the LFRG. Comprehensive Environmental Response, Compensation, and Liability ACT/Resource Conservation and Recovery Act Integration It is recommended that a PDAS and ODAS be issued for a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) facility that disposes of DOE radioactive waste at a DOE facility in addition to the Record of Decision (ROD) to clearly demonstrate DOE’s regulatory authority under DOE O 435.1. A ROD for a CERCLA disposal facility may be designated to serve as the DAS per DOE O 435.1. For any DOE LLW disposal facility that is also regulated by the EPA or a State regulator, DOE allows the Field site to submit documentation completed for the other regulator along with a crosswalk. Other CERCLA/RCRA documents can be used to demonstrate compliance with DOE O 435.1. However, separate documentation may be necessary for those requirements specific to DOE. In 7 Section 3116, Waste Determinations with Related Disposal Performance Assessments, Ronald Reagan National Defense Authorization Act (NDAA) for Fiscal Year 2005

DOE-STD-5002-2017 1-11 this manner, DOE maintains its regulatory authority while minimizing duplication. DOE and other regulators should work in parallel for facilities having overlapping regulations to ensure all regulatory issues are identified and resolved in an expeditious manner. In-Situ Closure Facilities closed in-situ (utilizing existing structures/facilities) may need to meet the requirements of DOE O 435.1. If an in-situ facility closure contains CERCLA waste from outside the established CERCLA area of contamination, a crosswalk should be developed showing how CERCLA analyses and documentation and any needed supplementary information, demonstrate reasonable expectation of compliance with the performance objectives/measures requirements in the Order. A DAS is not required in this instance. In-situ closure of radioactive facilities involving the placement of non-CERCLA waste (e.g., waste from site operations) into the facility should meet the requirements of DOE O 435.1 associated with the design, construction, operation, and closure of a LLW disposal facility, including the requirement for a DAS. CERCLA and non-CERCLA waste should not be co- mingled unless it is cost-effective and in the best interest of the government. Obtaining Waste Disposal Authorization The following sections describe the process for issuance of and revision to a DAS. The DAS may include specific requirements, conditions or limitations to the facility’s design, construction, operations, and closure. Specific evaluations may be performed to enhance DAS technical basis documentation. Failure to comply with DAS requirements or limitations may result in suspension of operations, or DAS revocation by the issuing authority. This Standard is the source for guidance regarding the format, content and review of technical basis documents supporting the DAS for a disposal facility. DOE O 435.1 takes precedent in the event a conflict exists between the Standard and the Order; the Standard takes precedent in the event of a conflict with DOE G 435.1-1, Implementation Guide for Use with DOE M 435.1-1. Preliminary and Operating DAS Technical Basis Documentation Review and Approval The LFRG is responsible for the independent regulatory review of DAS technical basis documents as delineated in Table 1-1 and for drafting of the DAS. The LFRG presents this draft to the responsible PSO for review and approval. In this capacity, the LFRG serves as the single point of contact between DOE HQ and facility personnel, both DOE and contractor, for all matters regarding the review of DAS technical basis documents. The LFRG site representative is responsible for coordinating any reviews with entities (i.e., NRC, EPA, state) having a vested interest through formal agreements or commitments associated with the facility. A DAS may be DOE-STD-5002-2017 1-12 granted when all the required technical basis documents have been reviewed, have met all applicable DOE O 435.1 requirements, and approved. The PA, CA and preliminary CP are typically developed first in the DAS process as these analyses influence other technical basis documents. The site may submit the PA and CA for LFRG review at the same time or separately. However, a DAS cannot be issued until all the required documents have been approved. Table 1-1 lists the review and approval responsibilities for the various technical basis documents. Table 1-1. Technical Basis Documents Review and Approval Responsibilities

Technical Basis Document LFRG at-Large (2) LFRG Site Member (3) Program Secretarial Officers (PSO) (1) Field Element Manager (FEM) Contractor Disposal Authorization Statements (preliminary and operational) Develop initial and revisions ------------- Review during PA/CA update NA ------------- Review during PA/CA update Approve initial and revisions NA NA Performance Assessment Review initial and revisions Review initial and revisions Approve initial through DAS Approves subsequent revisions through DAS updates or approval letter Concurs initial and revisions Develop Composite Analysis Review initial and revisions Review initial and revisions Approve initial through DAS Approves subsequent revisions through DAS updates or approval letter Concurs initial and revisions Develop DOE-STD-5002-2017 1-13 Technical Basis Document LFRG at-Large (2) LFRG Site Member (3) Program Secretarial Officers (PSO) (1) Field Element Manager (FEM) Contractor Closure Plan Review initial Review initial and revisions Approve initial through DAS Approves subsequent revisions through DAS updates or approval letter Concurs initial ------------- Approve revisions Develop Maintenance Plan Review initial Review initial and revisions Approve initial through DAS Concurs initial ------------- Approve revisions Develop Monitoring Plan Review initial Review initial and revisions Approve initial through DAS Concurs initial ------------- Approve revisions Develop Waste Acceptance Criteria Review initial Review initial and revisions Approve initial through DAS Concurs initial ------------- Approve revisions Develop Special Analysis Review if appropriate Review NA Approve initial and revisions Develop Annual Summary Report Review Review Review and approves continued operations Approve initial and revisions Develop Unreviewed Disposal Question Evaluations (UDQE) Review through Annual Summary Report Review (4) positive UDQE NA NA Develop and approve Unreviewed Composite Analysis Evaluations (UCAE) Review through Annual Summary Report Review (4) positive UCAE NA NA Develop and approve DOE-STD-5002-2017 1-14 (1) Office of Environmental Protection and ES&H Reporting (AU-20), is also responsible for review and approval of disposal documentation for TRU disposal at sites other than WIPP. AU is also a member of the LFRG and participates in the review and approvals. (2) LFRG at-large is composed of a group of Federal employees from sites that have radioactive waste disposal facilities and DOE-HQ personnel. This group may review the CP, MP, MonP and WAC revisions if the DAS is being revised. (3) LFRG site member is a member of the LFRG at-large with site specific disposal facility responsibilities. The LFRG site member has the responsibility to determine if a review of a revision to a technical basis document is needed by the LFRG at large. (4) Positive UDQE & UCAE exist when the criteria for these documents indicate further evaluation is necessary (e.g., SA is required). (5) DAS refers to Disposal Authorization Statement.

LFRG site members are responsible for determining DAS technical basis documents are complete, internally reviewed by appropriate personnel, and ready for LFRG review (LFRG Execution Plan provides detail on LFRG roles and responsibilities). The LFRG site members also ensure the contractor’s self-assessment against the LFRG review criteria for the particular technical basis document has been completed. Although the LFRG site member usually serves as the point of contact for an LFRG review team, other site personnel may be assigned this role. In this case, the LFRG site member should remain involved throughout in order to fulfill the regulatory responsibilities. LFRG site members are responsible for the timely resolution of any identified issues and for providing the LFRG with any issue’s closure documentation. Furthermore, the LFRG site member should notify the LFRG when he/she suspects facility operations warrant a DAS or Technical Basis Document(s) revision. The LFRG will assist in determining whether a DAS revision is necessary. LFRG Review Process Once the LFRG site member has confirmed the preliminary or operating DAS technical basis documents are ready for review, the LFRG designates a review team lead to manage the review and approval process. The LFRG ensures the review team lead is independent of the line organization responsible for DAS document preparation, and possesses the relevant technical competence. The review team lead’s responsibilities include: • Establishing a review team of technical experts; • Developing a review plan; • Coordinating communication between the site and review team; • Facilitating the on-site review; • Presenting a close-out briefing to site management; • Facilitating issue resolution; • Developing the final review team report; • Coordinating factual accuracy review with the site; and DOE-STD-5002-2017 1-15 • Submitting the team’s recommendation to the LFRG on the acceptability of the technical basis documents. Review Team Establishment LFRG review team members are selected based on their technical qualifications, experience, and expertise. Team expertise typically includes quantitative modeling, hydrology, geology, health physics, chemistry, radiological exposure analysis, engineering, waste management, DOE Order/regulatory compliance, and Quality Assurance (QA). Review team members should be independent (i.e., not a direct contributor to the documentation) of the facility being reviewed and are required to sign a conflict of interest form. Review team qualifications are detailed in LFRG Execution Plan. Review Plan Development The review team leader develops the review plan and works in coordination with the LFRG site member to ensure any necessary support and logistics are adequately addressed (e.g., access requirements, facility walkthroughs). Review plans should include: • Team member names, affiliation, bios, contact information, and the site personnel assisting with the review; • Review schedule: dates for review team pre-site visit meetings, the on-site review, and draft and final report availability; • The site’s self-assessment against the LFRG’s DAS technical basis document review criteria; and • Review criteria of the technical basis documents being evaluated and the review team members assigned responsibility for the criteria. Once the review team leader finalizes the plan, it is forwarded to the LFRG for a vote for approval. Plans for new facilities will likely contain the complete list of review criteria, while operating facilities may only contain a subset of the review criteria.

Document Review and Pre-Onsite Discussions Prior to the on-site review, the review team reviews the documents for adequacy and participates in meetings with site Federal and contractor personnel. These discussions may be conducted via telephone, webinar, or some other method as determined by the review team lead. In order to best assist the review team members in reviewing the documents provided, technical discussions are held covering all of the areas of expertise. The review plan provides guidance on planning and conducting these discussions. DOE-STD-5002-2017 1-16 The Field site personnel are responsible for documenting all questions and responses asked during the discussions. This resulting document, as well as any presentation material prepared by the site for the discussions will become part of the review record. Outside regulators (EPA, NRC, state) or other stakeholders may participate in these discussions at the discretion of DOE. The level of participation should be agreed upon prior to the review. On-Site Review On-site reviews are typically scheduled for five working days. The first day is usually a series of presentations by site personnel summarizing their assessments and conclusions, followed by a tour of the relevant site area(s). The remaining time involves in-depth discussions of the documents between review team members and site personnel. Team members document resolved and unresolved issues, observations or best practices. These issues or observations are gathered by the review team lead to be included in the review team report. The review team provides a close-out briefing summarizing its findings to site personnel and management. Review team findings should be categorized as: key issues, secondary issues, or observations. Additionally, review team members should identify any new and noteworthy practices observed during the review to assist in the continuous improvement of the LFRG process. The review team members should complete the review criteria matrix including: • Review criteria for the specific technical basis document being reviewed; • Notes or comments associated with the review of the criteria; • Key or secondary issues; and • Observations or best practices. The review criteria matrix becomes part of the final review team report. A key issue is a problem or concern that affects the validity or utility of the technical basis documentation. Key issues generally involve: • Technical errors that invalidate major conclusions relevant to meeting performance objectives/measures; • Failure to adequately substantiate a major assumption or technical position central to meeting performance objectives/measures; or • Failure to comply with a regulation or requirement. Sites should formally respond to all key issues. All key issues should be corrected or have an LFRG approved corrective action plan in place before a PDAS or ODAS can be issued. Key DOE-STD-5002-2017 1-17 issues remaining un-resolved should become a condition in the PDAS or ODAS, tracked in the MP and reported on in the ASR. A secondary issue is a problem or concern of sufficient importance that needs to be addressed, but does not constitute a key issue. Secondary issues typically involve: • A lack of clarity requiring a revision of text; • Insufficient documentation or references to fully support assumptions; or • Need for additional research to substantiate assumptions.

Sites should formally respond to secondary issues. Before the team leaves the site, secondary issues should be resolved or a corrective action plan should be provided to the LFRG. Typically, secondary issues do not require immediate corrective action. Unresolved secondary issues should become a condition in the PDAS or ODAS, tracked in the MP and reported in the ASR. Observations typically consist of recommendations to enhance the presentation of information and clarity of the document. Observations do not require a formal response and site personnel may exercise discretion in accepting or rejecting the recommendation. Best practices are DAS-related processes, procedures, modeling approaches, or other activities implemented at the site that the LFRG determines are cost effective, technically sound, and should be shared with other sites. Issue Response, Resolution, and Tracking The site may respond with the appropriate corrective actions to issues during the onsite review or prior to the LFRG final report. During this phase, site responses and corrective actions should be submitted to the LFRG review team lead. The review team lead transmits the responses to the team member who identified the issue to verify the adequacy of identified corrective action. If a response or corrective action is not adequate, the review team lead facilitates further dialogue to obtain a satisfactory resolution. The LFRG at-large serves as the final arbitrator if agreement is not reached. All key and secondary issues with their associated corrective action and resolution schedule should be tracked in a data base (See LFRG Execution Plan) by the LFRG until they are closed. The final disposition of all key and secondary issues should be documented, including dissenting views where applicable. Key and secondary issues not resolved during the onsite review, should be tracked by the site in the MP until closed and the status reported in the ASR. The LFRG Co- Chairs are responsible for assigning individuals/team to verify the issues have been properly closed. Closing secondary issues are discussed in the LFRG Execution Plan. DOE-STD-5002-2017 1-18 Final Review Team Report Submittal to the LFRG The review team report should identify: • All key and secondary issues, observations, and any best practices; and • The review team’s recommendation to: accept the document(s), accept it with conditions, or reject the DAS technical basis document(s). The review team report is finalized after a factual accuracy review by the site and any necessary modifications are completed. The final report should be submitted to the LFRG for review and approval. Once submitted to the LFRG, no changes can be made to the report except through an addendum to the report. The LFRG should vote on accepting, rejecting, or requesting the team to provide additional information before a decision is made on accepting the review team report. The LFRG may review additional information and reports or conduct other reviews, as necessary, to ensure that a thorough review has been performed of the facility’s technical basis documents. If the LFRG deliberations conclude the site is not ready to begin construction or operations, the LFRG should inform the cognizant PSO through a formal memorandum. Once the LFRG has completed deliberations, the LFRG develops a draft PDAS or ODAS for approval by the responsible PSO. The PDAS or ODAS should only be issued once the site has properly addressed the LFRG concerns and the LFRG Co-Chairs have made a formal recommendation to the responsible PSO to grant the DAS to the site.

Preliminary or Operation DAS Development and Approval The preliminary and operational DAS contents will vary depending on the disposal facility, but should address the facility’s background, site characteristics, design, construction, radionuclide limits, waste forms and packaging, monitoring, and closure. Outstanding issues may also be included as conditions in the DAS, particularly if an issue requires additional research or analyses. DAS examples are provided in the LFRG Execution Plan. When preparing a DAS for approval by the PSO, the LFRG also prepares a Compliance Evaluation Report (CER) summarizing key aspects of the disposal facility review. The CER should identify the basis for the LFRG recommendation for the operation of the facility. The basis should, at a minimum, be the LFRG review team report and any other information the LFRG used in making its decision and recommendation. The CER will vary according to the particular site being evaluated but will normally contain: • A summary of the LFRG review issues, including resolution schedules; • Complete corrective actions and agreed upon proposed corrective actions; DOE-STD-5002-2017 1-19 • LFRG recommendation to accept, accept with conditions, or reject the site’s request for a DAS; • LFRG Review Team’s recommendation if different from the LFRG’s recommendation; • Any additional reports or research and development required; • Comparison between PA/CA calculated and DOE O 435.1 performance objectives/measures; and • Basis for any DAS conditions or limitations. Drafts of CER and DAS documents are developed by a subset of LFRG members and approved by the LFRG at-large prior to submittal to the PSO for their approving signature. The DAS development, review and approval process is illustrated in Figure 1-3. DOE-STD-5002-2017 1-20 Figure 1-3. Disposal Authorization Statement Development, Review/Approval Flowchart DOE-STD-5002-2017 1-21 Preliminary and Operating DAS Maintenance and Revision Successful DAS maintenance depends on the periodic review of the technical basis documents as new information (site data, waste inventories, waste form and packaging) becomes available. Ensuring timely document revisions based on this enhanced understanding of operations is imperative. DAS compliance reviews may be initiated at any time by the LFRG, or other HQ organizations with responsibilities for line management or independent oversight of the disposal facilities. Should any activities call into question the adequacy of an existing DAS, the LFRG site member or the LFRG at large, may determine a revision is necessary. This determination should be documented. If required, the LFRG should develop a revised DAS for approval by the appropriate PSO. The DAS and associated technical basis documents should be revised, at a minimum, every ten years from the initial issuance of the DAS. A five to 10-year schedule for DAS revisions will be developed by the LFRG at large (see LFRG Execution Plan). References 10 CFR Part 830, Nuclear Safety Management 10 CFR Part 835, Occupational Radiation Protection Atomic Energy Act of 1954, NUREG-0980, U.S. Nuclear Regulatory Commission DOE Order 413.3B, Program and Project Management for the Acquisition of Capital Assets, November 29, 2010 DOE Order 435.1, Chg 1, Radioactive Waste Management, July 09, 1999 DOE Manual 435.1-1, Admin Chg 2, Radioactive Waste Management Manual, July 09, 1999 DOE Guide 435.1-1, 1 Admin Chg 2, Implementation Guide for Use with DOE M 435.1-1, July

09, 1999 IAEA. Disposal of Radioactive Waste, Specific Safety Requirements, No. SSR-5, International Atomic Energy Agency, 2011 IAEA. IAEA Safety Glossary – Terminology Used in Nuclear Safety and Radiation Protection, 2007 Edition, International Atomic Energy Agency, Vienna, 2007 IAEA. The Safety Case and Safety Assessment for the Disposal of Radioactive Waste, Specific Safety Guide No. SSG-23, International Atomic Energy Agency, Vienna, 2012. ICRP Publication 81, Radiation Protection Recommendations as Applied to the Disposal of Long-Lived Solid Radioactive Waste, International Commission for Radiological Protection, 1998 LFRG Execution Plan, Low-Level Waste Disposal Facility Federal Review Group, September 2015 DOE-STD-5002-2017 1-22 NCRP. Performance Assessment of Near-Surface Facilities for Disposal of Low-Level Radioactive Waste, NCRP Report No. 152, National Council on Radiation Protection and Measurements, Bethesda, MD, December 2005 NDAA Section 3116, Waste Determinations with Related Disposal Performance Assessments, Ronald Reagan National Defense Authorization Act (NDAA) for Fiscal Year 2005 DOE-STD-5002-2017 2-1 CHAPTER 2. PERFORMANCE ASSESSMENT GUIDE Introduction Goal The goal of this guide is to support the U.S. Department of Energy’s (DOE’s) initiatives to improve and maintain the highest quality radioactive waste management standards and activities throughout the DOE complex. The primary audience of this guide is the Federal Project Director and other DOE Federal/contractor employees involved in the disposal of low-level waste (LLW) and tank closure. Objective This chapter provides guidance to preparers of DOE or the National Nuclear Security Administration (NNSA) LLW, mixed low-level waste (MLLW), and Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) disposal facilities and liquid waste tank closure performance assessments (PAs) required by DOE Order (O) 435.1, Radioactive Waste Management. PAs prepared to address disposal of transuranic waste (TRU) should meet the requirements of 40 CFR Part 191, Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes. Key objectives for the preparation and associated Low-Level Waste Disposal Facility Federal Review Group (LFRG) review process are to ensure PAs are: • Complete and thorough; • Reasonable and logical; • Technically correct and defensible; and • Conclusions are valid and acceptable. Guides do not impose requirements but may quote requirements if the sources are adequately cited. This guidance follows the format of an objective statement, discussion, examples, a statement of one way to measure compliance, and supplemental references. Following this Guidance provides a consistent approach for compliance with the requirements of DOE O 435.1. If the Guide has not been followed, then an explanation/justification as to why a different approach is acceptable should be provided. The LFRG, functioning as the DOE regulatory authority, is the independent organization responsible for performing oversight of LLW disposal and tank closure in accordance with DOE O 435.1 [DOE Manual (M) 435.1-1, Radioactive Waste Management Manual, Chapter I, DOE-STD-5002-2017 2-2 2.E(1)(a)]. Therefore, the LFRG members utilize this Standard as guidance in performing oversight functions and judging compliance with the requirements of DOE O 435.1 (See LFRG Execution Plan for details of LFRG roles, responsibilities and processes).

Background The DOE conducts activities, including disposal of LLW and remediation of radioactive contamination at DOE sites that could potentially result in long-term radiological exposure to future members of the public. These activities should, therefore, be conducted in a manner that is not only protective of the public during facility operations, but also ensures that future members of the public will be protected from the aggregate of all residual radioactive material on a DOE site. PAs and composite analyses (CAs) are conducted as part of the process employed by DOE to address radiological protection of the public. PAs are used to provide DOE with a reasonable expectation that LLW disposal will meet the radiological performance objectives established in DOE O 435.1. PAs are reviewed and approved by DOE Headquarters (HQ) and are part of the basis for a Disposal Authorization Statement (DAS) to be issued by the appropriate Deputy Assistant Secretary or Deputy Administrator containing conditions for operation and waste receipt at the disposal facility being evaluated. It is not possible to provide absolute assurance of the performance of the disposed waste and various sources of radioactive material at some future time. Rather, the DOE O 435.1 requires that the PA be prepared to provide a reasonable expectation that the performance objectives will not likely be exceeded. The PA for active and planned LLW disposal facilities is focused only on the disposal facility so that design and operational controls may be established to ensure that performance objectives will be met. PAs are focused on meeting the performance objectives for protection of the public established in DOE M 435.1-1 for the waste that is disposed in the facility after September 26, 1988. Contributions to cumulative dose for future exposures from sources disposed in a facility prior to September 26, 1988, and other sources that are significant contributors from outside the facility are addressed in the CA. Role of PA During Facility Lifecycle. PAs play an important role throughout the development of a disposal facility for siting, design, construction, operations and considerations for closure. Calculations are used for a variety of other specific needs in addition to the role for demonstrating compliance with performance objectives. During siting, initial PA calculations can be used to assess the feasibility of different sites and to begin to explore the need for engineered barriers. PAs have a significant role during the design stage or tank cleaning stage as part of the total systems approach for assessing performance of different combinations of natural and engineered barriers. PA calculations are used to consider different design alternatives and to provide a basis for the selection of specific design options. DOE-STD-5002-2017 2-3 During construction or tank closure activities PAs are used to assess as-built conditions and any design changes introduced during construction. PA plays a key role during operations for the establishment and maintenance of Waste Acceptance Criteria (WAC) and also for SAs. Note that the term PA is used throughout this chapter, but in many cases the guidance could also be addressed in a special analysis (SA) (see Chapter 8). Assumptions in the PA also form the technical basis for development of requirements in the monitoring and closure plans (CPs).

Relationship between PA and CA. PAs are closely linked with CAs, which DOE uses as planning tools to ensure that the combined effect of all sources of radioactive material that could significantly contribute to the dose calculated from LLW disposal and closed underground liquid waste storage tanks will not violate the requirements for the protection of the public. In some cases, with limited interactions with other sources, it may be possible to document the CA as an appendix or supplement to the PA. If the PA and CA are combined it will be necessary to include additional information (hydrogeology, facility descriptions, source characteristics, etc.), as appropriate, with the information needed to ensure that the review criteria for CAs are also satisfied. PAs and CAs are not decision documents. The PA provides evidence of compliance with performance objectives for protection of the public and the environment, and for development of WAC, monitoring plans (MonPs) and CPs. The DAS is the ultimate decision document, which relies on the results of the PA and CA and other technical basis documents to support the decision to approve or not approve operations of a disposal facility or tank closure action. Development and maintenance of the PA and CA are iterative processes and the maintenance plan (MP) is used to document the plans to implement the iterative approach. Annotated Outline for Performance Assessments Executive Summary The Executive Summary should provide a summary of the PA including the results compared to the performance objectives and key assumptions and information important to understand the factors with the greatest influence on the PA and conclusions made therein. Information in this summary should include: • A table with the results of the PA for each of the performance objectives and the intrusion analysis; • A discussion of potential peaks beyond the compliance period; • Pathways and radionuclides that are significant contributors to dose for each objective and measure; • Critical assumptions and parameters relative to compliance; DOE-STD-5002-2017 2-4 • Key operating and closure conditions and assumptions; • Regulatory context including land use assumptions; and • A summary of the conclusions of the PA. Objective The objective of this guide is to describe the results of the PA compared with the appropriate performance objectives and measures. The Executive Summary also identifies key assumptions and provides a summary of the conclusions of the PA. Discussion This requirement provides a concise summary of the results and conclusions from the PA. Results from the analysis are provided in a table for quick reference (Table 2-1). The example table includes peak impacts during the compliance period and also includes some description of peaks that may occur after the compliance period. Peaks that may occur after the compliance period can also be described in the text and may be addressed quantitatively or qualitatively depending on the timing and site specific considerations. It can be helpful to also include a column in the table identifying the pathways and radionuclides that are the primary contributors to peak impacts or this can be described in the text.

Key assumptions that can influence the conclusions of the PA and/or need to be protected in the design and/or operational procedures are also discussed. Note the emphasis is on assumptions that could change the conclusions regarding compliance rather than simply assumptions that have a significant impact on the results. This discussion includes assumptions or parameters identified in a sensitivity or uncertainty analysis and design features or operational practices that were credited in the PA (e.g., assumed placement of specific wastes, cover thickness, etc.). Table 2-1. Example Summary of PA Results from a Disposal Facility Performance Objective and/or Measure Standard Performance Assessment Results Compliance Period (2035-3025)a Post-Compliance Period (3015-12035)a All pathways (DOE O 435.1 Chg 1) 25 mrem/yr EDE 1.02 mrem/yr 1.88mrem/yr Atmospheric (40 CFR 61, Subpart H) 10mrem/yr EDE 1.02 mrem/yr 0.51 mrem/yr DOE-STD-5002-2017 2-5 Performance Objective and/or Measure Standard Performance Assessment Results Compliance Period (2035-3025)a Post-Compliance Period (3015-12035)a Atmospheric (40 CFR 61, Subpart Q) 20 pCi.m-2.s-1 radon flux (at surface of disposal facility) 0.11 pCi.m-2.s-1 0.08 pCi.m-2.s-1 Acute inadvertent intruder (DOE O 435.1 Chg 1) 500 mrem EDEb 5.51 mremf NA Chronic inadvertent intruder (DOE O 435.1 Chg 1) 100 mrem/yr EDEb 9.27 mrem/yrf NA Groundwater protection (water resources) (40 CFR 141) Beta-gamma dose equivalent < 4 mrem/yr 0 mrem/yr 3.3c mrem/yr Gross alpha activity concentration (excluding radon and uranium) < 5 pCi/L 0 pCi/L 1E-10d pCi/L Combined Ra-226 and Ra-228 concentration < 5 pCi/L 0 pCi/L 1E-10d pCi/L Uranium concentration < 8 pCi/Le 0 µg/L 1E-10d µg/L Sr-90 concentration < 8 pCi/Le NA NA H-3 concentration < 20,000 pCi/L 0 pCi/L 1E-10d pCi/L a. Compliance at 100 m downgradient of Environmental Restoration Disposal Facility (ERDF) except for inadvertent intruder scenarios b. Not applicable for post-compliance time period. c. Beta-gamma dose equivalent < mrem/yr (based on Federal MCL) and calculated as (CPeak/MCL)*4 mrem/yr For Tc-99, which contributes almost the entire dose, CPeak = 731 pCi/L and MCL = 900 pCi/L, so the equivalent does is calculated to be 3.3 mrem/yr d. Concentrations less than 1E-10 pCi/L are essentially zero. e. Not applicable; Sr-90 was screened out during evaluation of the groundwater pathway due to its relatively short half-life and its low mobility I the subsurface. f. Peak dose based on assumed inadvertent intrusion at 100 years following loss of institutional control. Peak occurs at 100 years after closure. EDE = effective dose equivalent MCL -= maximum contaminant level NA = not applicable. DOE-STD-5002-2017 2-6 Introduction The introduction should provide background documenting why the PA was required and a high- level overview of the technical approach used in the development of the PA, including a content summary, and the relationship of the disposal facility (or other facility) to be closed as a LLW facility to any existing and potential future programs at the DOE site. This section should identify high-level assumptions about the facility that are critical to the analysis of performance, as well as changes in those assumptions from previous PAs or other similar analyses. 2.2.2.1 Basis for Performance Assessment

This section should summarize the reason necessitating the PA (e.g., PDAS to support construction of new disposal facility, change in design/layout, and accumulation of changes such that an update was deemed appropriate). It should provide background material, or reference to previously published documents that define PA scope and changes in assumptions from existing PA/CAs and other analyses to which the PA may be compared, as applicable. Objective The objective of this guide is to serve as a reference point identifying the underlying basis for the PA and identification of previous PAs and the presence of other analyses to which the PA may be compared. Discussion This subsection provides a frame of reference for the need for the PA and provides a single place for a reviewer to be made aware of previous PAs and other assessments. If the PA is a revision to close any outstanding secondary issues from an earlier PA, the issues should be specifically identified. If there is potential for the PA to be compared with other analyses, this section should refer the reader to “Related Analyses” in this chapter for a description of those analyses. The emphasis at this point is on identification and awareness of differences from previous PAs and other analyses. Detailed descriptions of modeling assumptions, etc. will be provided later in the PA, but general statements about the impacts of changes in assumptions on results of the PA are helpful in this overview with reference to the more detailed description. Example: A new PA is being conducted to address a new disposal concept and new waste streams that will be disposed. The PA also includes an updated conceptual site model with changes in assumptions regarding the vadose zone and underlying aquifer. This subsection introduces the changes to the disposal facility, the waste streams not considered in the previous PA, updates to the conceptual site model and a reference to where the new information is described in detail. The changes DOE-STD-5002-2017 2-7 are provided in a bullet list with citations for more detailed discussions. General statements about the influence of the changes on the PA results can also be included (e.g., the new site data is expected to result in reduced doses because Kd values have been increased for a given radionuclide). 2.2.2.2 General Facility Description The General Facility Description should provide a short summary description of the waste disposal concept, facility, location, and waste operations. The description should include: • LLW disposal concept (e.g., vault, trench, tanks); • Historical development and use; • Generation, treatment, storage and disposal steps; • WAC and waste tracking systems; and • Waste characterization & certification program(s) summary. Objective This guide provides a summary of the disposal concept and site providing perspective on the relative importance of natural and engineered barriers. The waste management system associated with the disposal facility is also described. Discussion This subsection introduces important features at the site, the disposal facility location and the disposal concept and provides a description of the general steps in the waste management process from generation to treatment to staging/storage and disposal operations. WAC and waste tracking systems are also described as part of a summary of the waste characterization and certification program at the site. 2.2.2.3 Design Features

This section should provide perspective about the overall safety strategy, including a higher-level system view of how the components described in the “Site and Facility Characteristics” section function together to meet the performance objectives. This section should also identify significant design and operating constraints that are driven by considerations outside of the PA, and identify any safety analysis reports (SARs) associated with operation. This section should summarize: DOE-STD-5002-2017 2-8 • Disposal concept; • Engineered features (waste forms, containers, vaults, caps, drainage systems, closure assumptions): o Safety roles of engineered and natural features in terms of reducing releases; and o Key interdependences between the different engineered and natural features affecting overall performance. • General state of knowledge related to system behavior; • Operational considerations that may impact long-term safety and feature protection; and • Operational requirements, such as WAC, relevant to the long-term performance. A figure or table illustrating/describing the different features of the facility and site and their roles for safety of the facility as considered in the PA should be provided. Objective This guide provides an introduction to the safety strategy for the disposal facility and natural system, including defense-in-depth considerations. Changes from previous PAs should be identified as part of the descriptions. Discussion This subsection provides an introduction to the integrated safety system, including different site and engineered features that make up the total disposal system that will be described in the “Site and Facility Characteristics.” The description serves as an initial summary of the safety functions for key design features (e.g., waste forms, containers, vaults, covers, drainage systems, general closure assumptions) and considerations for development of conceptual models to be used for the PA. General perspective on evolution of the system is provided, including identification of interdependencies between barriers that could introduce counter-intuitive behavior (e.g., assuming increased recharge through cover while tank is still intact may not be conservative). Figure 2-1 is an example summarizing the evolution of the performance of different features in a disposal system over time. DOE-STD-5002-2017 2-9 Figure 2-1: Example of Evolution of Performance of a Disposal Facility Over Time The description also should provide an initial indication of which features are included/excluded from consideration in the PA, what needs to be defended with the PA, and the general state of knowledge related to the behavior of the system. For engineered features, links should be provided to more detailed descriptions that would be provided in “General Facility Description.” For new facilities, there will also be a systems evaluation conducted as part of the sensitivity analysis or reference to an evaluation in an Appendix or supporting document (Attachment 2.1). Defense-in-depth considerations are also highlighted for features that are not part of the conceptual model, but contribute to safety (e.g., specific operational controls, WAC, barriers that are not credited in the PA models, etc.). As part of the discussion, significant changes in assumptions from previous versions of the PA should be identified (e.g., those changes that would be of interest to a reviewer or stakeholder). Modeling implications associated with those changes are discussed in “Related Analyses.” Operational considerations that may impact long- term safety should also be introduced in this section. The section should identify SARs associated with operation of the facility and operational requirements, such as WAC, waste placement requirements, etc. relevant to the long-term performance of the disposal facility. The intent is to capture design and operating constraints that are driven by considerations outside of

DOE-STD-5002-2017 2-10 the PA (e.g., constraints that would require the need to consider changes to documentation beyond the PA before they could be modified). 2.2.2.4 Low-Level Waste Disposal Facility Lifecycle and Closure Plan This section should summarize the expected chronology for the operating life cycle of the disposal facility or tank farm through final closure, and identify any changes from assumptions in a previous PA. The summary should include, as applicable: • Waste disposal operations specific to disposal units prior to September 26, 1988; • Waste disposal operations specific to disposal units from September 26, 1988 to present; • Forecasted waste disposal operations specific to disposal units from present to end of operations; • Any plans for installation of operational, interim and final covers from the present to the planned final closure (closure, active institutional control, and post-institutional control); and • A summary of key assumptions related to facility closure that need to be captured in the CP (Chapter 4). In the case of tank closure, a general description of the life cycle of the tank farm, followed by a summary of the schedule for closure of the tanks is prepared to address the content in the first three bullets above. Objective This guide provides details about historic and planned operations at the disposal facility or tank farm and identifies disposal units that are specifically considered and not considered in the PA. Assumptions regarding the timing of the planned closure of the facility are also specifically described. Discussion This subsection identifies the operational periods and closure status for all disposal units in the disposal facility including tank farms for tank closure PAs. Disposal units specifically considered in the PA are identified based on the timing of waste disposal or tank closure activities and site-specific considerations. A key aspect of this description is to identify changes in general operating plans from those considered in previous assessments (e.g., timing of facility start-up, timing of cover installation) that are important for the PA. For disposal facilities that began operation before the effective date of the Order, there may be specific units, or waste in a specific unit, excluded from consideration in the PA based on timing of disposal. These wastes DOE-STD-5002-2017 2-11 should also be identified and should be addressed in the CA. Key closure assumptions (e.g., timing of cover placement, assumed infiltration rates prior to and after final closure, etc.) that should be protected and documented in the CP are also identified in this subsection. Example: Liquid waste tanks at a site were operated prior to September 26, 1988, but closure decisions and actual closure will be completed after the effective date of the Order. Thus, residual waste that will be left in those tanks should be considered in the PA. Example: Disposal operations for a given unit within a disposal facility began in 1984, which is before September 26, 1988. Since the unit includes waste disposed before and after the effective date of the Order, it was decided in that case to include all of the waste disposed in the unit in the PA for the disposal facility. This is not required, but was a choice made for that situation. Whether or not the waste disposed prior to the effective date of the Order was included in the PA, it would have to be addressed as a potential source for the CA.

2.2.2.5 Related Analyses This section should identify previous or on-going PA/CA-related analyses or other analyses at the site [e.g., risk assessments, National Environmental Policy Act (NEPA), etc.] that could be compared with the PA. Citations to relevant documents should be included. Significant differences in assumptions and results that may exist between the PA and any other pertinent modeling activities that may be compared with the PA (including changes to address comments on previous versions of the PA) should be identified and summarized to: • Help reviewers focus on un-reviewed aspects that have changed from previous modeling efforts; and • Address any differences in assumptions/results that could be seen as inconsistencies. Objective This guide identifies other modeling efforts that could be a point of comparison for modeling in the PA and serves to identify and explain different assumptions that may have been made. Discussion Multiple modeling efforts may be underway at a DOE site at any given time, especially larger sites, and assumptions may change when a PA is updated. There are often differences in the DOE-STD-5002-2017 2-12 level of detail or general approach taken for modeling depending on the purpose. The modeling may support different regulatory programs, be overseen by different DOE Field Offices at the site, and be conducted by different contractors or even different groups within a contractor. Inevitably, assumptions, approaches, and results from the PA will be compared with other similar efforts that may have been conducted at a given site (e.g., previous PAs, Environmental Impact Statements (EISs), risk assessments). These factors lead to a potential for apparent inconsistencies in modeling results, if the context of the modeling is not explained. It is important to acknowledge those differences and be prepared to explain the basis and significance. This subsection expands on the introduction to other modeling efforts that could be compared with the PA listing the other analyses and identifying specific assumptions in the PA that differ from other modeling efforts and a brief discussion of the impacts on the results. From a general perspective, the intent is to demonstrate an awareness of other modeling efforts and an understanding of any significant differences. Note that differences from previous versions of the PA may be introduced in “Related Analyses” and discussed here with reference to more detailed descriptions later in the PA or in other documents. Example: A NEPA-related analysis was recently completed at the DOE site that included contributions resulting from releases from the PA facility. For the broader purposes of the EIS, the releases from the facility were assumed to not be attenuated by physical barriers around the waste. In the PA modeling, some credit was taken for the barriers that resulted in lower release rates. When results from the two models are compared, the EIS suggests higher release rates than the PA. This subsection would introduce the differences in assumptions and provide a general statement about potential impact on the results with reference to the section of the PA or other document describing the detailed assumptions for the modeling. 2.2.2.6 Regulatory Context

This section should describe site specific regulatory context for the PA, including but not limited to the performance objectives, timing and point(s) of assessment, considerations for intrusion, and any relevant agreements between the DOE, Nuclear Regulatory Commission (NRC), the U.S. Environmental Protection Agency (EPA), other Federal agency, or the state. It should summarize activities undertaken to engage interested parties in development of the PA, including any agreements or commitments resulting from those activities (e.g., scoping meetings, modeling workshops, etc.). DOE-STD-5002-2017 2-13 If the PA is being conducted to support a CERCLA disposal cell, this section should provide references to relevant documentation that is used as supporting material for the PA (e.g., Remedial Investigation/Feasibility Study (RI/FS) documents, risk assessments, crosswalks) and describe the approach for integration (e.g., cross referencing to specific details in a risk assessment and/or RI/FS). This section should also describe stakeholder engagement and any institutional relationships, agreements, or commitments to provide the regulatory context that may affect the performance criteria or PA approach. 2.2.2.6.1 Performance Objectives The performance objectives for all pathways, air, radon and groundwater protection should be specified. If for a particular site, there are performance objectives derived from other requirements (e.g., site-specific regulatory agency agreements), additional sections should be provided to discuss these agreements. This section should describe the pathway analysis from the facility only-background and other sources should not be included. The descriptions of the performance objectives should reflect the choice of a deterministic or probabilistic approach to compliance. The greater of the peak of the mean or median results should not exceed the applicable performance objectives for probabilistic approaches. All Pathways. This section should describe the site-specific application of the requirement to provide a reasonable expectation that representative members of the public will not receive a total effective dose resulting from the disposal facility in excess of 25 mrem (0.25 mSv) in a year from all exposure pathways, excluding the dose from radon and its progeny in air. All pathways include the reasonable modes by which a representative receptor at the point of public access is assumed to be exposed, including the air pathway, groundwater pathway, direct contact, and consumption of contaminated foodstuffs, as applicable at a given site. Air Pathways. This section should describe the site-specific application of the requirement to provide a reasonable expectation that representative members of the public will not receive a total effective dose via the air pathway in excess of 10 mrem (0.10 mSv) in a year, excluding the dose from radon and its progeny. This includes dose as a result of direct inhalation, immersion, and exposures from deposition of radionuclides transported via the air pathway, as applicable at a given site. Radon Release. This section should describe the site-specific application of the requirement to provide a reasonable expectation that release of radon will not exceed 20 pCi/m2/s (0.74 Bq/m2/s) averaged over the surface of the disposal facility or concentrations will not exceed 0.5 pCi/L (0.0185 Bq/L) at the appropriate boundary.

Water Resources. This section should describe the site-specific application of the requirement to provide a reasonable expectation that impacts to water resources will not exceed applicable DOE-STD-5002-2017 2-14 EPA, state, or local regulatory requirements. Impacts should be assessed on a site-specific basis in accordance with the following hierarchical set of criteria: • First, the DOE facility should comply with any applicable State or local law, regulation, or other legally applicable requirement for water resource protection. • Second, the facility should comply with any formal agreement applicable to water resource protection that is made with appropriate State or local officials. • Third, if neither of the above conditions apply, the site should select assumptions for use in the PA based on criteria established in the site groundwater protection management program and any formal land-use plans. • If none of the above conditions apply, the site should select assumptions for use in the PA for the protection of water resources that are consistent with the use of water as a drinking water source unless there is formal agreement that the water is not considered suitable for drinking water. • For groundwater as a drinking water source, the point of assessment (POA) should be the location of highest concentration in a drinking water source outside a 100-meter buffer zone surrounding the disposed waste. Objective Site specific implementation of the performance objectives that serve as the basis for determination of protection of human health and the environment at the POA during the time of compliance are described. Discussion The performance objectives provide a measure of disposal facility performance in limiting impacts to a member of the public from all pathways, water resource protection, air dose and the release of radon over the time of compliance. The disposal facility includes the buffer zone around the facility, the area underneath the facility to the aquifer and the area above the surface of the facility. The performance objectives were established in DOE O 435.1 to assure compliance with the requirements of DOE O 458.1, Radiation Protection of the Public and the Environment. They are generally consistent with the objectives established by other regulatory agencies (NRC, EPA) and the recommendations of the International Atomic Energy Agency (IAEA). Performance objectives are used as one of the limiting factors to establish WAC for the disposal facility operations including but not limited to allowable radionuclides and their concentrations, acceptable waste matrix, and containers. The performance objectives are enforced in the context of the compliance period and migration of radionuclides within the performance objectives are considered Federally authorized releases. Default assumptions for DOE-STD-5002-2017 2-15 performance objectives, measures and POA are summarized in Table 2-2. Additional guidance is provided following the table. Table 2-2. Example Default Exposure Scenarios, Performance Objectives and Measures, and Points of Assessment for the Performance Exposure Scenario Objective or Measure Point of Assessment Operational & Active Institutional Control Periods d Post-Institutional Control Period PERFORMANCE OBJECTIVES FOR COMPLIANCE All-pathways 25 mrem/yr a DOE Site Boundary 100 m c Air pathway 10 mrem/yr a DOE Site Boundary 100 m c Radon 20 pCi/m2/s Flux rate at Facility

surface Flux rate at Facility surface 0.5 pCi/L b Facility Boundary 100 m c Water Resources Per State and local requirements 100 m c 100 m c PERFORMANCE MEASURES Intruder 100 mrem/yr chronic a Not applicable Facility 500 mrem acute a Not applicable Facility Note: The disposal facility includes the buffer zone around the facility, the area underneath the facility to the aquifer and the area above the surface of the facility. “Facility surface” refers to releases from the waste into the atmosphere. “DOE site boundary” is the overall site boundary defined in land use plans. a. Excluding radon in air. b. Alternate radon Performance Objective. c. The point of highest projected dose or concentration beyond a 100-meter buffer zone surrounding the disposed waste. A larger or smaller buffer zone may be used if adequate justification is provided. d. The active institutional control period includes final closure. Probabilistic Results. If calculations are performed probabilistically, the peak of the mean or median of the distribution of results, whichever is higher, should generally be used to compare with the performance objectives over the compliance period. Other results from the distribution should be used to inform the decision in conjunction with the results of sensitivity analyses and to assess a need for reduction in uncertainty via PA and CA maintenance, but no specific numerical criterion should be applied to other percentiles. Other indicators, such as the mean of the peaks, are not appropriate for the purposes of demonstrating reasonable expectation of meeting the performance objectives. DOE-STD-5002-2017 2-16 Example: The Site X PA was performed probabilistically. The results of the exposure calculations over the 1,000-year assessment period are that the peak of the median of the dose distribution is 15 mrem/year, the peak of the mean is 18 mrem/year, and the 95th percentile is 110 mrem/year. Sensitivity and uncertainty analysis results and an ALARA analysis were used to address the 110 mrem/yr dose. The combinations of assumptions resulting in the 95th percentile results were reasonably unlikely and it was determined that a reasonable expectation of compliance was demonstrated. Thus, the PA results are compliant with the 25 mrem/year performance objective. NRC supports the use of central tendencies for distributions (i.e., mean, median) when comparing probabilistic results with deterministic standards. Some rationale for NRC opinions regarding the use of central tendencies is explained in NRC SECY-97-221, Acceptance Guidelines and Consensus Standards for Use in Risk-Informed Regulation, and further elaborated in NRC Regulatory Guide 1.174, An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (e.g., pages 1.174 – 21 & 22). In these documents, it is stated that the use of central tendencies as a basis of comparison should be supplemented by qualitative judgments and sensitivity analyses to address uncertainties associated with, e.g., the model and overall completeness of the analysis. In this respect, it is emphasized that simply showing the mean or median is below the standard is not sufficient in itself. Information on the tails of the results distribution become increasingly dependent on specific assumptions regarding the input distribution, which may not be well defined. There may also be a need to address cost/benefit of reducing uncertainty via the PA and CA maintenance process.

. There is a need to maintain some perspective regarding interpretation of specific results on the tails recognizing the many different factors, biases, and different types of uncertainties that can affect the distributions of results. The use of the peak of the mean or median reflects the emphasis on using a central tendency rather than extremes when determining compliance. Although, the distributions of results will suggest that some higher doses could occur, the likelihood of an exposure actually occurring is generally not captured in the standard PA approaches. Thus, there is additional pessimism implicitly included in the distribution of the results by assuming that an exposure will occur at the point and time of the peak concentration for the assumed exposure scenarios. These factors should be discussed to provide context for the conclusions regarding compliance with the performance objectives. All Pathways Dose. Consistent with established radiation protection practices articulated by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency Basic Safety Standards Radiation Protection and Safety of Radiation Sources: DOE-STD-5002-2017 2-17 International Basic Safety Standards (IAEA 2011), the projected dose attributable to any single source, practice, or activity should be some fraction of the applicable overall dose limit. Depending on the particular source of concern, DOE and the NRC have typically established limits of 10 to 25 percent of the primary dose limit for protection of the public [100 mrem (1 mSv/year)] to any particular source, although higher or lower fractions may be appropriate. This performance objective is used to provide a reasonable expectation that representative members of the public will not receive more than 25 percent of the primary dose limit of 100 mrem (1mSv) in a year from the disposal of low-level waste. The requirement addresses the annual total effective dose, inclusive of all potential exposure pathways (e.g., groundwater, surface water, air) except for dose from radon and its decay products in air for which a separate performance objective (rate of radon release or concentration in air) is stated. All pathways include the modes by which a receptor at the point of presumed public access could reasonably be exposed to radioactive material migrating, via environmental media (e.g., water, soil, biota, air), from the disposed waste. “Reasonably exposed” in this context refers to the acceptable practice of using stylized representations of typical exposure pathways and scenarios representative of current habits and technologies in the region and should not be perceived to involve worst case or highly unlikely exposure scenarios. Radon and its decay products are considered separately from other radionuclides in the all pathway calculations consistent with 10 CFR Part 40, Procedures for Transportation Workplace Drug and Alcohol Testing Programs, (Appendix A, Criterion 6), 40 CFR Part 190.10(a) Standards for Normal Operations, and 10 CFR Part 20, Section1101(d) Radiation Protection Plans. Even though a separate performance objective is established for the air pathway, the air pathway is also included in the all pathways dose calculation.

The performance objective is applied in terms of dose to a representative member of the public to indicate the dose objective is not intended to be applied for assumptions regarding the age, sex, or assumed activities of any specific member of the public ICRP Publication 101, Assessing dose of the representative person for the purpose of radiation protection of the public and optimization of radiation protection: Broadening the process. The ICRP terminology used for this representative member of the public at the time this document was prepared is “Representative Person” (DOE O 458.1, ICRP Publications 101, and ICRP Publication103, The 2007 Recommendation of the International Commission on Radiological Protection). The use of the “representative person” construct addresses the fact that the performance objectives are generally applied, through the PA process, to hypothetical future members of the public, rather than to known and identified individuals. Use of the Representative Person construct is consistent with the use of the current recommended dose coefficients that have been developed for a “reference person” (DOE-STD-1196-2011, Concentration Technical Standard). The term “reference person” refers to the assumptions for development of dose coefficients (e.g., human body) and the term “representative person” refers to the assumptions for the receptor in the DOE-STD-5002-2017 2-18 performance assessment (e.g., more highly exposed member of the critical group). Also, see “Exposure Pathways and Scenarios” for further discussion. Air Pathway Dose. This performance objective requires a reasonable expectation that representative members of the public will not receive from the disposed waste, via the air pathway alone, more than 10 mrem in a year, excluding the dose from radon and its progeny. The choice of 10 mrem/yr (0.1 mSv/yr) for this objective is drawn from the EPA National Emission Standards for Hazardous Air Pollutants (40 CFR Part 61, Procedures for Transportation Workplace Drug and Alcohol Testing Programs, Subpart H). Consistent with 40 CFR Part 61, Subpart H, dose from radon and its progeny are not included in assessing compliance with this performance objective. The air pathway dose includes dose, as applicable, as a result of direct inhalation, immersion and exposures from deposition of radionuclides transported via the air pathway from the waste in the disposal facility being addressed in the PA. The effectiveness of covers, waste forms, containers and other barriers can be considered, as appropriate, in the air pathway calculations. In some cases, relatively simple calculations (e.g., a box model) can be sufficient to demonstrate compliance for a LLW disposal facility. If such an approach is used, it is important to document the assumptions and identify features that were not credited in the calculations. This provides a starting point to revise calculations in the future where it may be desirable to include credit for features that were not credited in the initial calculations.

Radon Exposure. This performance objective requires a reasonable expectation that radon, either as a constituent of waste at the time of disposal or produced by radioactive decay following disposal, is not released from the disposal facility at a rate that would exceed the limit established in 40 CFR Part 61, Subpart Q, National Emission Standards for Radon Emissions from Department of Energy Facilities. Compliance with this performance objective could address either of the two limits contained therein. The rate of radon release, over time, from the surface of the disposal facility could be projected for comparison with the flux limit. Alternatively, the concentration of radon in air could be projected for comparison with the concentration limit. In most cases, the ground surface emanation rate of 20 pCi/m2/s (0.74 Bq/m2/s) should be applied. However, in cases where the disposed waste radiologically resembles uranium or thorium mill tailings, the use of the limit on air concentration may be warranted. Alternatively, doses from radon and progeny may be included in the assessment of compliance versus the 10 mrem in a year air pathway performance objective. In this case, assuming that compliance with the 10 mrem in a year dose limit is projected, radon need not be addressed separately. Any of these approaches may be used to demonstrate that radon releases are within levels that are protective of human health. The PA should identify which approach is applied. DOE-STD-5002-2017 2-19 Water Resources. This performance objective includes calculations of surface or groundwater concentrations and/or drinking water doses for comparison with applicable Federal, state or local surface or groundwater protection standards to establish limits on radionuclides that may be disposed in near-surface disposal facilities. DOE O 435.1 does not specify the level of protection for water resources that should be used in a PA for a specific low-level waste disposal facility, because surface or groundwater protection is typically addressed by other regulations at the state and/or local level. Thus, a site-specific approach, in accordance with a hierarchical set of criteria should be followed. This approach recognizes that there are no Federal requirements for protection of water resources for a radioactive waste disposal facility. The site-specific hierarchical approach, rather than mandating specific performance objectives for all sites, is consistent with the EPA strategy for water resource protection, which recognizes that groundwater protection is a state and local matter. The hierarchy reflects that applicable state or local laws will be the first drivers for water resource protection. In this case, the term “applicable” has some emphasis to reflect that not all water resource protection laws are universally applicable. It is important to assess the applicability of a standard within the context of the waste disposal facility and land use/institutional control plans. Example: (Compliance with state requirement for water resources protection.) The closest water resource impacted by the disposal facility is the groundwater. Peak concentrations during the compliance period 100 m downgradient from the disposal site are analyzed to determine if it meets the drinking water standards as specified by 40 CFR Part 141.66 over the compliance period. The impact on groundwater resources will be evaluated by comparing the predicted groundwater concentrations against the drinking water standards. The State of Washington has adopted the Federal drinking water regulations (revised as of July 1, 2009) for MCLs for radionuclides in Washington Administrative Code Title 246, Chapter 246-290 (WAC 246-290-025 and WAC 246-290-310), Radiation Protection Standards. As a result, no separate calculations are needed to satisfy the State of Washington drinking water standard.

The second and third options refer to any formal agreements that have been made that establish criteria for the protection of water resources. The fourth option can potentially refer to standards for protection of drinking water either at a state or Federal level (e.g., 4 mrem/yr effective dose equivalent for beta/gamma). It is important to consider whether it is appropriate to use Maximum Contaminant Levels (MCLs), other derived concentration limits, or a 4 mrem/yr dose standard. Note that in cases where it is not specified to use an MCL, use of a 4 mrem/yr drinking DOE-STD-5002-2017 2-20 water dose standard for water resource protection allows for use of current DOE approved dose coefficients rather than relying on older dosimetry used to develop the MCLs. 2.2.2.6.2 Point of Assessment and Timing Assumptions This section should provide the basis and assumptions for the points of assessment and associated time of assessment. During operations and active institutional controls, the POA for all pathways and the air pathway objectives are at the site boundary. Radon flux and radon concentration POAs are at the surface of the facility and facility boundary respectively. The POA should correspond to the point of highest projected dose beyond a100 m buffer zone surrounding the disposed waste following the loss of institutional controls, except for the radon flux, which is assessed at the surface of the cover. Water resource protection is applied at the 100 m buffer zone during operations and active institutional controls and after loss of institutional controls. Table 2-2 includes a summary of the locations of the POAs. The POA should be consistent with Land Use and Institutional Control Assumptions. The buffer zone is 100 m from the disposed waste assuming the footprint of the disposal facility extends below ground and into the air above the facility. A larger or smaller buffer zone may be used if adequate justification is provided. The location of the POA and timing of the hypothetical loss of institutional control leading to potential intrusion should be based on justification provided in the Land Use and Institutional Control Assumptions (e.g., regulatory agreements, site-specific conditions) and design and engineering considerations (e.g., effectiveness of waste forms, containers or barriers in deterring intrusion for longer times). This section should also refer to the requirement in DOE O 458.1 for DOE to maintain control of land until it can be safely released or transferred to another party. The peak during a 1,000-year time period after facility closure for the entire facility should be used for direct comparisons of results for compliance and as a basis for the disposal facility’s WAC. This section should provide documentation to support an assessment period greater than 1,000 years, if required by other DOE programs and plans; or by other applicable Federal, state, or local statutes, regulations, or agreements. The approach for addressing potential peaks beyond 1,000 years should also be described. Objective Site specific implementation of assumptions for the POA and time of compliance are described. Discussion A site developing a PA should include the necessary content with sufficient detail for reviewers to identify the time of compliance, approach to address potential peaks after the time of DOE-STD-5002-2017 2-21 compliance, and POA for each performance objective and the inadvertent intruder performance measure.

Point of Assessment. DOE is required to maintain control over land containing radionuclide sources until the land can be safely released pursuant to DOE O 458.1 or transferred to another authorized party. In spite of this requirement, it is generally assumed that following the 100-year active institutional control period, a member of the public could reside near the disposal facility. The POA is the location of the highest projected dose outside of the buffer zone. A default buffer zone can be assumed that includes the area projected through the aquifer below, in the air above and extending horizontally with a 10 footprint surrounding the disposed waste (i.e., 100 m surrounding the disposed waste does not imply that the POA is in the air 100 m above the waste or to the aquifer, the POA is the point of highest concentration at least 100 m from the footprint of the disposed waste). The information in Land Use and Institutional Control Assumptions is used to provide the basis for the assumptions regarding the location of different types of receptors and can also be used to describe the basis for any deviation from 100 m. The use of peak concentrations in space and time around the facility implements the International Commission on Radiological Protection (ICRP) expectation to consider more highly exposed members of the public. The POA can change as a function of time depending on the nature of the releases from a disposal facility and evolution of the plume. The concept of a buffer zone is inherent in defining a low-level waste disposal facility and a 100 m buffer zone is consistent with assumptions for 10 CFR Part 61. The disposal facility is comprised of a number of disposal units (e.g., earthen trenches, tumuli, and vaults), the space between disposal units, and space around the collection of disposal units. This latter space is called the buffer zone. The buffer zone provides some radionuclide containment capability, as well as controlled space to establish monitoring locations and, as necessary, modify or supplement the design of the disposal facility. Consistent with established radiation protection practices articulated by the National Council on Radiation Protection and Measurements (NCRP) and the ICRP, the projected dose attributable to any single source, practice, or activity should be some fraction less than the applicable overall dose limit. The requirement provides flexibility in establishing the extent of the buffer zone considering site-specific issues. In certain instances, e.g., if the disposal facility is located adjacent to the current DOE site boundary, it may be more appropriate to use a smaller buffer zone. In other cases, e.g., where the disposal facility is located far from the DOE site boundary, and the site’s land-use planning does not envision relinquishing control of the site, a larger buffer zone, potentially extending to the site boundary, could be considered. In any case, justification for the selection of the buffer zone should be provided. The justification for the selection of the point of compliance and size of the buffer zone is based on land use plans and commitments that have been negotiated during consent agreements or DOE-STD-5002-2017 2-22 other regulatory actions. If land use planning has not progressed enough for commitments to exist, the justification could also be based on published information about site boundaries in documentation such as EISs. The justification could also be based on the proximity of already existing contaminated areas or nearby operational facilities that establish a boundary, or which would render the 100-meter point of compliance as unreasonable.

The buffer zone is to be established based on land use planning and commitments, a reasonable judgement concerning nearby facilities and areas of contamination, and natural borders (see example below). The buffer zone cannot be established arbitrarily, or moved to a specific distance to achieve a disposal objective, such as accommodating a large concentration of a mobile radionuclide. Example: A low-level waste disposal facility is located in a quadrant of the DOE site that includes several contaminated areas and other waste management facilities. The current land use plan negotiated with stakeholders at the site, and which is incorporated by reference in the Consent Order at the site, shows this land remaining under DOE control. The buffer zone for this facility is extended out to a point about half way between the disposal facility boundary and the site boundary. In the intruder assessment, it is assumed that there is a temporary loss of passive and active institutional controls after 100 years following disposal facility closure. The timing of this hypothetical loss of institutional control can be extended beyond 100 years based on justification provided in the Land Use and Institutional Control Assumptions (e.g., regulatory agreements, site-specific conditions) and/or design and engineering considerations (e.g., effectiveness of waste forms, containers or barriers in deterring intrusion for longer times). Approaches that have been successful for expanding the extent of a buffer zone or extending the time of effectiveness of institutional controls generally involve formal agreements with regulators to maintain controls over the facility or the land including the facility. The effectiveness of barriers in delaying the potential for inadvertent intrusion is discussed in the section on the Hypothetical Inadvertent Intruder in this Guide. Active Institutional Control Period. Institutional control, for the purposes of PA, is assumed to last for a minimum of 100 years. Longer periods may be assumed with sufficient justification (e.g., formal regulatory agreements). However, the actual period of institutional control, when DOE maintains a custodial presence and controls the use of the land, is required to be maintained until the facility can be released. A low-level waste disposal facility or closed tank cannot be released until the requirements for public and environmental radiation protection of DOE O 458.1 for releasing a facility for unrestricted use are met. Institutional controls are no longer DOE-STD-5002-2017 2-23 necessary for a facility released for unrestricted use. Institutional controls are also addressed in “Land Use and Institutional Controls.” For low-level waste disposal facilities and tank closure, the period of active institutional control could extend long beyond 100 years before the requirements of DOE O 458.1 are met. The CP includes the necessary activities to be performed during this period of institutional control to ensure the protection of the public health and the environment, such as facility monitoring, custodial maintenance, access controls, corrective actions, passive controls and restrictions, reporting requirements, and record keeping. The determination of the necessary activities to be performed during the institutional control period is based on the documentation and analysis included in the facility radioactive waste management basis, including the performance assessment, composite analysis, closure plan, and monitoring plan. Institutional control measures should be incorporated into the site’s land use and stewardship plans, programs and procedures to ensure that control of the site is not compromised. Throughout the period of institutional control, the responsibility for maintaining the facility to protect the public and the environment rests with the Field Element Manager (FEM).

Compliance Period. The compliance period is defined as a 1,000-year period after the assumed facility closure. A 1,000-year compliance period should be used for direct comparisons of results with the performance objectives in the context of compliance and as a basis for the disposal facility’s WAC. 1,000 years is viewed as a reasonable time frame over which calculations have sufficient credibility and meaningfulness on which to base decisions regarding quantitative compliance. Beyond 1,000 years, assumptions and calculations become increasing speculative and uncertain and results need to be viewed with increasing caution. It is recognized that there may be circumstances where a regulator or other stakeholder requests calculations for a different time frame. In such a case, the basis for the different time frame needs to be described to clarify the purpose of the calculations. Nevertheless, 1,000 years is not viewed as a cutoff to calculations, rather it is considered a point of transition in how results are interpreted. DOE expects that potential peaks will be addressed for times after 1,000 years. However, in the context of decision-making, peaks occurring at increasing time frames are addressed in an increasingly risk-informing and qualitative manner rather than from the perspective of quantitative compliance with a performance objective. Peaks occurring shortly after 1,000 years will be viewed more critically than peaks occurring many thousands of years in the future. An important consideration is changes in assumptions that could shift a peak from after 1,000 years to before 1,000 years (e.g., overly optimistic Kd values or barrier lifetimes that delay the appearance of a peak). Consideration of potential peak impacts after 1,000 years is intended to provide additional information to support decision making. The calculation of potential peaks in the far future does present the possibility that there may be results that exceed the performance objectives. The DOE-STD-5002-2017 2-24 significance of these results needs to be addressed with caution and judgment recognizing the context of the assumptions on which the calculations are based (conservatism, speculation, uncertainty). The further out in time that the peak impacts are projected to occur, it becomes more important to take a risk-informed view of the significance of the specific values that are calculated relative to the inherent uncertainties. The discussion of peaks that may occur after 1,000 years represents best management practice in the conduct of PAs, but those maxima may be presented in forms other than a dose. The level of quantitative rigor expected for such calculations is also reduced for longer time frames consistent with the presence of increasing speculation and uncertainties associated with human evolution and catastrophic natural events that will overwhelm the effects of parametric uncertainties in the models. Nevertheless, consideration of performance for longer time frames should be used to provide additional insights about the behavior of the model of the site and the system being modeled that would not be available if the calculations were truncated at the time of compliance. This additional information may be useful in evaluating alternative designs and optimization of protection [As Low As Reasonably Achievable (ALARA)].

Potential alternatives to a strict dose limit for times beyond 1,000 years have been discussed. The concept of complementary safety indicators (e.g., concentrations or fluxes in the environment, comparisons against background, etc.) gained increasing attention in the mid-to- late 1990s and has subsequently appeared in international recommendations and standards. The term “peak impacts” is used rather than peak dose in this Standard to reflect the use of complementary safety indicators to provide additional perspective when considering performance in the far future. The recognition of the role of complementary indicators of impacts to aid decision-making for very long time frames reflects the ICRP position that dose estimates “should not be regarded as measures of health detriment beyond times of around several hundreds of years into the future” (ICRP 1998). Examples of complementary safety indicators include concentrations in the environment and fluxes in the environment or through engineered features (also see IAEA 2003, Safety Indicators for the Safety Assessment of Radioactive Waste Disposal – Sixth Report of the Working Group on Principles and Criteria for Radioactive Waste Disposal; IAEA 2012, The Safety Case and Safety Assessment for the Disposal of Radioactive Waste). As introduced above, although calculations can be conducted for any selected time frame, caution should be exercised when interpreting dose results over time frames beyond several hundred years. For example, ICRP Publication 81, Radiation Protection Recommendations as Applied to the Disposal of Long-Lived Solid Radioactive Waste, International Commission for Radiological Protection, includes the following recommendations regarding the role of judgment when considering long-term projections: “Demonstration of compliance with the radiological criteria is not as simple as a straightforward comparison of calculated dose or risk with the constraints, but DOE-STD-5002-2017 2-25 requires a certain latitude of judgment. Neither should estimated transgression of a constraint necessarily oblige rejection, nor should numerical compliance alone compel acceptance of a waste disposal system. The dose or risk constraints should increasingly be considered as reference values for the time periods farther into the future, and additional arguments should be duly recognized when judging compliance [emphasis added].” “To evaluate the performance of waste disposal systems over long time scales, one approach is the consideration of quantitative estimates of dose or risk on the order of 1,000 to 10,000 years. This approach focuses on that period when the calculation of doses most directly relates to health detriment and also recognizes the possibility that over longer time frames the risks associated with cataclysmic geologic changes such as glaciation and tectonic movements may obscure risks associated with the waste disposal system. Another approach is the consideration of quantitative calculations further into the future making increasing use of stylized approaches and considering the time periods when judging the calculated results. Qualitative arguments could provide additional information to this judgmental process.” The IAEA 2012 also includes recommendations regarding the consideration of very long time frames beyond 1,000 years for near surface disposal facilities:

“Safety assessment calculations should cover a time period that is long enough to determine the maximum, or peak, dose or risk. However, this may not always be possible. For example, in the case of disposal of long lived waste (e.g., from uranium mining) on or near the surface where there is uncertainty in the durability of engineered barriers (e.g., dams and covers), doses and risks may remain constant or may even increase long into the future, through time frames in which uncertainties in the assessment increase significantly and limit the meaningfulness of the assessment. This may limit the timescale for the assessment in general, or at least the timescale for quantitative assessments.” “For above surface disposal facilities (e.g., for waste from mining), the uncertainties in modelling results will already be substantial when considering periods of several hundred years, and quantitative estimates may become meaningless already beyond a period of a thousand years. For engineered near surface disposal facilities, which are subject to processes that may affect their integrity (e.g., erosion, human intrusion) to a lesser degree or with a smaller probability, modelling periods of a few thousand years may still be reasonable.” Thus, ICRP and IAEA recommendations support the concept that peaks occurring after 1,000 years for near surface disposal can be interpreted in a more qualitative, risk-informed context to DOE-STD-5002-2017 2-26 include comparisons to background radiation levels and concentrations, average annual exposure, trends in radionuclide releases relative to natural fluxes etc. rather than focusing strictly on quantitative, compliance-oriented comparisons to a dose constraint. This reflects the potential for catastrophic changes in the natural environment over these times. It is advocated to use calculations after 1,000 years to increase the understanding of the models and assumptions used and to optimize designs, but the results are not considered a requirement for directly determining compliance with the performance objectives. Likewise, they should not be ignored when considering acceptance of a disposal facility. Probabilities associated with consequences also become more important when considering very long time frames. Individual deterministic results become less significant in terms of decision making over very long times, because of the increasingly speculative nature of the results. Thus, there is an increasing need to consider likelihoods in conjunction with consequences at those longer time scales. Example: A situation in which a qualitative assessment of all pathways peak impact may be in order is an arid site characterized by an aquifer that lies far below the surface of the disposal facility. Under normal circumstances, the small amount of precipitation falling on the site results in low rates of infiltration through the disposal units. Radionuclides leached from the waste are slowly transported downward to the aquifer; a journey that may require thousands to tens of thousands of years to complete. The outcome may be peak groundwater impacts that occur well after 1,000 years. Faced with these conditions, quantitative modeling would be extended to estimate the migration of radionuclides for a period of several thousand years after the disposal facility undergoes final closure. Subsequently, a qualitative discussion would be provided that considers the potential for further impacts beyond this time in the context of the growing uncertainties associated with the evolution of the local geology, climate and human activities. This discussion might rely on projections of groundwater flow rates, taken from the quantitative modeling, and information about the decay and sorption properties of the radionuclides leached from the various sources to provide a broad estimate of when contaminants may appear in the aquifer. Lacking quantitative modeling, estimates of the magnitude of any exposures received far into the future would not be provided. However, general statements about the potential for impacts greater than those estimated during the initial thousands of years may be possible.

Example: The results of a PA for an engineered, near-surface disposal facility suggest that peak impacts may occur after 1,000 years. To address the potential peaks in the DOE-STD-5002-2017 2-27 far future, quantitative sensitivity and uncertainty analysis calculations are extended for several thousand more years. Interpretation of these calculations is focused on identifying the key safety functions of the engineered and natural features that influence the timing and magnitude of the peak that is projected to occur. This is accomplished by identifying the assumptions having a significant influence on releases of key radionuclides from the waste form as well as the fluxes out of the disposal facility and concentrations in the natural environment. These results are used to identify design assumptions that can significantly influence the magnitude of the releases. Design modifications are proposed that are expected to reduce the magnitude of the peak and addressed in the ALARA analysis. Calculations of groundwater concentrations in the aquifer are also provided to illustrate the potential for catastrophic increases in impacts. The concentration results indicate that although some increases could potentially occur, the increases are not considered catastrophic in the context of the increasingly speculative nature of the uncertainties associated with the natural environment and human activities in the far future. Additional arguments are provided to address the potential for increases in concentrations at longer times beyond the calculations, but the increases were not considered significant in relation to the other potential catastrophic changes in the surface environment (e.g., ice ages). 2.2.2.7 Inadvertent Intrusion Reasonable efforts should be made to provide engineered and administrative controls to address the potential for and/or consequences of doses to a hypothetical, inadvertent human intruder that may disrupt the disposal facility. Intrusion is assumed to occur after a temporary loss of institutional controls and memory of the disposal facility. The stylized analyses (i.e., drilling and basement excavation) for inadvertent intrusion should be based on credible (reasonably expected) exposure assumptions for current site-specific practices. The likelihood of inadvertent intruder scenarios can be considered when interpreting the results of the analyses and establishing radionuclide concentrations that can be disposed in the facility, if adequate justification is provided. It is more common to provide some qualitative discussion of likelihood to place results in perspective. The results from the assessment of human intrusion should be considered as part of developing limits on the concentration of radionuclides that can be disposed in the facility (i.e., WAC). Active institutional controls are assumed to be effective in deterring intrusion during the period of active institutional control (usually 100 years) following the end of operations at the disposal facility. Delays beyond 100 years should be justified in the “Land Use and Institutional Control” assumptions or, for engineered/design features, should be justified in the detailed description of the analysis. DOE-STD-5002-2017 2-28

The potential for acute and chronic exposure scenarios should be considered. Acute scenarios involve exposures of people conducting drilling or excavation activities for a limited period of time (e.g., drilling a well, excavating a basement for a home). Chronic scenarios involve individuals establishing a residence and being exposed to materials exhumed from the site and distributed on the ground surface. Chronic exposure is assumed to result from external exposure to, and direct and indirect inhalation and ingestion of (e.g., plant uptake, bio-accumulation, etc.) radionuclides in the waste. This analysis should use 100 mrem annual total effective dose, excluding doses from inhalation of radon and progeny, as the performance measure for chronic exposure from residing at or frequently visiting the disposal site following an intrusion event. The analysis should use 500 mrem total effective dose, excluding radon and progeny, as the performance measure for acute exposures during the event assumed to result in the disruption of the waste. Objective Site specific implementation of the performance measures and assumptions to consider potential inadvertent intrusion are described. Any assumptions that delay or preclude inadvertent intrusion relative to the default assumptions are also introduced. Discussion Although DOE intends to exercise control of the LLW disposal facility or tank closure facility until it can be safely released pursuant to DOE O 458.1, there is a requirement to consider the impacts of potential inadvertent human intrusion. However, since it is hypothetical and unexpected, intrusion is considered to be an accidental, temporary event and is compared with a performance measure rather than a performance objective. This perspective is consistent with ICRP and IAEA recommendations [ICRP Publication 81 and the IAEA Disposal of Radioactive Waste, Specific Safety Requirements (IAEA 2011)] to consider inadvertent intrusion in the context of optimization rather than against a dose constraint. Nevertheless, the results of inadvertent intrusion analyses are used as an input for development of waste concentration limits that would be considered when developing WAC for a disposal facility. The intrusion event should be considered to occur due to a lapse in passive controls, after active institutional controls are assumed to be lost, that would be remedied within a time frame that limits the exposure time to one year or less. Notably, there is general international consensus that these requirements do not apply to the protection of individuals that knowingly/intentionally intrude into a disposal facility. Timing of Intrusion. In the intruder assessment, active institutional controls are assumed to be effective in preventing intrusion for at least 100 years following disposal facility or tank closure; longer periods of institutional controls may be assumed with justification (e.g., land-use DOE-STD-5002-2017 2-29 planning, passive controls). Active institutional controls, as applied here, means that there is human involvement and an active presence in controlling and maintaining the facility.

It is not expected that there would be a complete loss of memory on day one following the end of active controls. It is possible to take credit for passive controls (e.g., records, land use restrictions, etc.) to extend the time of institutional control, although this is not common and requires substantial justification (e.g., formal expert elicitation, documented agreements with site regulators). Note that, in the context of activities conducted under 10 CFR Part 20, Standards for Protection Against Radiation, the NRC considers state or Federal government ownership and control to provide the most durable level of institutional controls (see NUREG-0706, Final Generic Environmental Impact Statement on Uranium Milling, Project M-25, Vol. 1, M.2). The timing assumptions need to be consistent with the information in “Land Use and Institutional Controls.” Engineered features of the disposal/closure system such as intrusion barriers in a cap, concrete vault, or the waste form, may also be effective in deterring inadvertent intrusion into the facility for an extended period of time. If barriers are credited for delaying intrusion, degradation of the barriers (e.g., erosion, subsidence, biointrusion, concrete degradation, etc.) needs to be addressed and durability against intrusion should be defended based on current drilling and basement construction practices in the region. For inadvertent intrusion analyses in the context of Tank Closure PAs, it is generally accepted that a closed tank (e.g., filled with grout) is considered to be a robust, stable form. Thus, inadvertent drilling into a closed tank can be assumed to only occur after 500 years, which is consistent with NRC scenarios considered for developing the classification system in 10 CFR Part 61. Note that other features in a tank farm (pipelines, etc.) are generally assumed to not provide a significant barrier, thus inadvertent intrusion is assumed to possibly occur following the assumed loss of institutional controls. Credit for longer delays beyond the 100-year active institutional control period or 500 years for robust, stable waste forms (e.g., robust concrete barriers), respectively, may be possible with proper justification based on local conditions. Substantial justification (e.g., independent review) should be provided. Stylized Analyses and Performance Measures. Inadvertent intruder assessment is conducted using a limited set of illustrative scenarios. DOE provides a framework for stylized scenarios using two classes of exposures consistent with scenarios considered for the classification system in 10 CFR Part 61. Residential/future use and active construction/drilling activities are considered. The residential or future use scenarios are referred to as Chronic (long-term, lower exposure) and the drilling/construction scenarios are referred to as acute (shorter-term, higher exposure). If the doses from chronic or acute scenarios can be demonstrated to bound the doses of the other scenarios, only the bounding type of scenario needs be analyzed and presented in detail. DOE-STD-5002-2017 2-30

Two performance measures are considered in intrusion assessments. For chronic exposure scenarios (i.e., continuous or ongoing exposures for a hypothetical resident at the facility after an intrusion event), the performance measure is 100 mrem (1 mSv) in a year, total effective dose. Thus, applies to exposures associated with waste remaining in the facility and cuttings/excavated material brought to the surface as a result of the intrusion. DOE’s use of 100 mrem/yr for chronic scenarios by DOE rather than 500 mrem for chronic scenarios used for the basis for 10 CFR Part 61 provides some added margin. With this more restrictive value, DOE does not require that contributions from the groundwater pathway be included in this analysis. The underlying assumption is that groundwater protection is sufficiently addressed in the water resources and all pathways dose performance objectives, which use performance objectives significantly less than 100 mrem/yr. For acute exposure scenarios (i.e., one time only events or single exposures to hypothetical people involved in constructing a basement or drilling a well), the performance measure is 500 mrem (5 mSv) in a year, total effective dose. Doses from the progeny of radon that are present in the disposed waste should be included in the intruder analyses, but the chronic and acute performance measures exclude doses from radon and its progeny via the air pathway. Basement evacuation scenarios use the assumption that a 3m deep excavation is made [[NUREG-1757, Vol 2, Consolidated Decommissioning Guidance, Characterization, Survey, and Determination of Radiological Criteria, NUREG/CR-4370, Update of Part 61 IMPACTS Analysis Methodology, Kennedy and Peloquin (1988)8]. The drilling scenario is generally based on drilling practices in the local area. However, each of these scenarios may not need to be assessed in all cases (e.g., maintaining > 3m of clean cover, even after erosion or other natural processes, will preclude excavation of waste during a basement scenario) or drilling or excavation scenarios may be delayed by robust barriers as described above. It is generally expected that some form of drilling scenario will need to be considered after barriers have degraded. The use of stylized scenarios addresses the need to ensure that PAs do not become extreme in their analyses via undue speculation about the activities and lifestyles of future generations. Thus, the requirement is to assume that customs and practices of today continue into the future for the purposes of a stylized/illustrative analysis. This provides a more common basis across the complex for conducting analyses. The representative person construct should also be used for dose calculations for the inadvertent intruder scenarios. In general, intruder scenarios should be developed considering the following: • Intruders may carry out activities for no more than about a year before discovery. 8 Kennedy, Jr., W.E. and R.A. Peloquin, Intruder Scenarios for Site Specific Low-Level Radioactive Waste Classification, DOE/LLW-71T, 1988 DOE-STD-5002-2017 2-31 • An intruder may perform reasonable activities consistent with regional social customs and well drilling, excavation, and construction practices, and the regional environmental conditions projected for the time that intrusion is assumed to occur.

• Intrusion events may involve random contact with waste, but some materials may serve as effective barriers to direct contact. This could apply for activated metals and reinforced concrete vaults or containers for the time frame that they maintain sufficient integrity depending on drilling methods. • An intruder will usually take reasonable, investigative actions upon discovery of unusual materials. • Intrusion events that contact waste may be assumed to be limited to drilling or simple excavation scenarios involving use of relatively unsophisticated tools and commonplace machinery. • Doses calculated for an intruder will depend on waste disposal facility design and operating practices, and may be reduced and/or delayed by practices such as disposal below depths normally associated with common construction activities, use of engineered barriers or durable waste forms or containers, or distributed disposal of higher-activity waste. Example: A disposal facility is developed in a location comprising soils and unconsolidated sediments. The facility includes the use of reinforced concrete barriers above the waste. Common drilling methods for wells in the area are designed to drill through soils rather than robust materials. Thus, it is assumed that a drilling scenario that would penetrate the reinforced concrete barrier would not be reasonably expected to occur until the barrier is assumed to lose its physical integrity. Thus, the impacts of inadvertent intrusion are not assumed to occur at 100 years and are delayed until several hundred years in the future. For the purposes of establishing waste acceptance requirements on the disposal facility or evaluating potential impacts of tank waste residuals, the likelihood of intruder scenarios may be addressed. Justification of intruder scenarios’ probabilities needs to be included if used in the intruder assessment. As an alternative, a qualitative discussion can be included describing the relative likelihood to provide perspective on the robustness of the system, but not formally credited in the analysis. Example: Expert elicitation was conducted to identify a reasonable estimation of the probability of inadvertent intrusion. The process resulted in a probability distribution reflecting a range of probabilities that inadvertent human intrusion DOE-STD-5002-2017 2-32 would occur that were applied in a probabilistic PA. Figure 2-2 is an illustration of the distribution that was used, where the central, most likely value of the distribution is roughly a 10 percent probability of occurrence. Estimated distribution of the overall probability of IHI overlaid on the simulated relative frequency distribution. Figure 2-2: Example of a Distribution of the Probability of Inadvertent Intrusion Justification for probabilities of scenarios or timing of scenarios can also include consideration of engineered barriers and their effectiveness in delaying or precluding potential intrusion. For example, robust steel reinforced concrete vaults or containers can serve to preclude the potential for drilling or basement construction to contact the waste while they maintain their integrity. The design of a container could also serve to reduce the probability of contacting the waste when drilling (e.g., potential deflection of the drill bit). There is also a likelihood associated with the potential for direct contact with any specific container in the context of the areal extent of the DOE-STD-5002-2017

2-33 disposal facility. Although inadvertent intrusion should be assumed to occur at the time of loss of institutional controls, it can be assumed to be a random event within a disposal facility. Example: Site X has disposed of a discrete higher activity waste form after conducting a Special Analysis to supplement the approved PA, to demonstrate that the disposal of the waste form will be within the performance objectives and measures specified in this Order. The random location of a hypothetical inadvertent intrusion within the footprint of the facility was considered when addressing the likelihood of direct contact with this specific container. 2.2.2.7.1 ALARA Analysis The ALARA process should be used to optimize the LLW disposal facility performance by applying a graded approach to optimization of the disposal system for maintaining doses to members of the public (both individual and collective) and releases to the environment as low as reasonably achievable, per DOE O 458.1. This analysis should reflect a graded approach recognizing the relative hazards associated with disposed waste as compared to other nuclear operations when considering the need for design or other modifications of disposal facilities or other closure activities. Objective Describe the approach applied for the PA to consider ALARA requirements. The details for the analysis and results may be provided here or can be provided in a specific section. Discussion DOE’s approach to radiation protection for LLW disposal is based on two key components. One component is the performance objectives described above, which specify maximum impacts for various pathways. The other component is the ALARA principle where impacts should also be optimized below the performance objective. DOE has developed a handbook (DOE-HDBK-1215-2014, Optimizing Radiation Protection of the Public and the Environment for use with DOE Order 458.1, ALARA Requirements) to assist program and field offices in understanding what is necessary and acceptable for implementing the ALARA provisions of DOE O 458.1, which are also applicable for DOE O 435.1. The handbook identifies the goals, requirements and issues that need to be addressed when developing ALARA analyses for optimization of various programs to support DOE’s diverse missions. Various case studies and examples are also provided to further assist in implementing the ALARA process. DOE-STD-5002-2017 2-34 DOE’s ALARA process helps ensure that optimization techniques will be integrated into the design and analyses of programmatic options necessary for the protection of the public and the environment in accordance with the requirements of DOE O 458.1. As much as possible, DOE sites should consider using existing processes, programs or documentation for addressing the provisions of DOE O 458.1 and DOE O 435.1 in the development and implementation of the ALARA process. It is important to recognize that optimization is not minimization. Optimization is the result of an evaluation that carefully balances the benefits from exposure reduction (e.g., health, regulator and public goodwill, etc.) with the costs (e.g., economic, schedule, social, etc.). Thus, the best option is not necessarily the one with the lowest dose. Potential long-term hazards associated with waste disposal considered in PAs are generally low relative to active nuclear facility operations. Thus, it is important to use a graded approach to address ALARA requirements. DOE-HDBK-1215-2014 includes recommendations to help guide the necessary level of analysis (Figure 2-3):

“It is difficult to be prescriptive in setting guidelines for the level of ALARA analysis because many factors – both technical and societal in nature – can influence such an evaluation. A detailed quantitative ALARA analysis may only be necessary for major actions. DOE has therefore opted to provide flexibility in selecting the level of analysis. “Reference” dose levels have been established to help determine the level of effort required for an ALARA analysis. In general, if the dose to the maximally exposed individual (MEI), or the representative person of the critical group, is much less than 1 mrem (0.01 mSv) in a year and the collective dose to the exposed population is less than 10 person-rem in a year, only a qualitative ALARA analysis is warranted. When doses are near the reference levels, it may be necessary to evaluate the alternatives semi- quantitatively. However, if individual doses are significant compared to the primary dose limit, e.g., tens of millirem in a year, or the collective dose exceeds 100 person-rem in a year, a quantitative ALARA analysis is recommended.” DOE-STD-5002-2017 2-35 Figure 2-3. General Guidance for Determining the Level of ALARA Analysis Required Per DOE-HDBK-1215-2014, a qualitative ALARA analysis is done by describing alternatives and comparing the costs and benefits without estimating their monetary or numerical values. A simple “pros and cons” analysis is an example of a qualitative type of analysis. A semi- quantitative ALARA analysis develops alternative descriptions and estimates of the costs and benefits which can be enumerated readily, but may lack a comprehensive numerical comparison employing all factors. Although numerical criteria (some subjectively assigned) may be used to help rank alternatives in the decision process. Examples of the different types of analyses are provided in the handbook. Example: An EIS was prepared to consider alternatives for waste tank closure at the site. The EIS considered social, technical, economic and public policy aspects. Thus, the selected option from the EIS has addressed key considerations for an ALARA analysis and the options considered and conclusions from the EIS can be cited as part of the basis for demonstrating meeting the ALARA requirement. Furthermore, NDAA Section 31169 and DOE O 435.1 require that highly radioactive radionuclides be removed from the tanks to the maximum extent practical, which is another ALARA consideration. The PA included a variety of calculations and sensitivity and uncertainty analysis to consider the impact of different design and barrier assumptions and to consider peaks well beyond the 9 National Defense Authorization Act (NDAA), Fiscal Year 2005 (NDAA FY2005) DOE-STD-5002-2017 2-36 1,000-year compliance period. Given the variety of cases considered, other documentation of alternatives analysis, and the fact that the peak doses for the compliance period were below 1 mrem/yr for the compliance case, it was determined that a quantitative ALARA analysis was not necessary for the PA. 2.2.2.7.2 Other Requirements This section should summarize any requirements that should be met per external regulations (e.g., Resource Conservation and Recovery Act (RCRA), CERCLA, 40 CFR Part 191) and the means for demonstrating compliance (e.g., via separate documentation for those regulations, crosswalk). This may include: Records of Decision for environmental restoration under CERCLA, agreements for remedial action under RCRA, agreements associated with tank closure [e.g., NDAA Section 3116 of P.L. 108-375, Waste Determinations with Related Disposal Performance Assessments (NDAA FY2005)], or agreements on groundwater management and protection.

Objective Identify and describe any additional regulatory requirements or agreements that apply and the approach used to meet those requirements. Discussion This section of the PA should present a discussion of all applicable relationships for the disposal facility or tank closure between the waste management assessments, plans, and evaluations at the DOE site to provide the site-specific regulatory context within which the PA has been prepared (e.g., closure, monitoring, and land-use plans, site treatment plans, environmental impact statements, ground water protection management plans). This section should also describe any institutional relationships, agreements, or commitments that may affect the performance criteria for the disposal facility, including any stakeholder workshops or meetings that were convened. As applicable for the disposal facility or tank closure, the following examples should be identified and discussed or citation provided for further discussion in the PA (e.g., land use in ”Land Use and Institutional Controls”: • Any relevant agreements between the DOE, the EPA, or other Federal agency, including other offices from DOE (e.g., NNSA, NE, Office of Science (SC), etc.) or the state, including agreements or Records of Decision (RODs) for environmental restoration of waste disposal sites under CERCLA, agreements for remedial actions under RCRA, or agreements on groundwater protection, and any other relevant agreements; • Any planned or completed evaluations or documents prepared to comply with the NEPA, with mention of the specific activities evaluated in each document; and DOE-STD-5002-2017 2-37 • Any SARs in accordance with DOE Order requirements, and any operational requirements, such as waste acceptance requirements or information relevant to the long-term performance of the disposal facility. Tank closure and development of disposal facilities for remediation wastes involve external regulators and additional regulatory requirements. These additional requirements often involve a need to prepare different documentation with redundant information (e.g., a PA and a remedial investigation/feasibility study). A crosswalk may be prepared that identifies the location of the information required for the PA that was prepared in other regulatory documents. The crosswalk needs to be specific enough for a reviewer to easily identify the information provided in the other documentation to satisfy content requirements and review criteria for the PA (e.g., citations should be page and section specific, as applicable). When determining the appropriate location for a given description or analysis, it is expected that DOE-specific requirements (e.g., inadvertent intrusion, dose calculations) are documented in the PA, because DOE has the authority for the review and compliance determination. Executive Order 13653, Preparing the United States for the Impacts of Climate Change, was issued to address sustainable practices and take actions to consider potential impacts of climate change. For waste disposal, this will include operational safety and long term performance impacts addressed in the PA and CA. From a PA and CA perspective, potential climate change impacts are addressed by considering potential changes in the natural system (e.g., changes in erosion/deposition, changes in infiltration/recharge).

It is generally recommended to submit a draft crosswalk to the LFRG Co-Chairs for informal review early in the PA process. This is also an opportunity to gain approval to deviate from the recommended structure of the PA report in this Standard. 2.2.2.8 Land Use and Institutional Controls This section should summarize the current predominant land use and assumptions regarding future land use in vicinity of the disposal facility that influence the timing and location of points of assessment used for compliance. The summary should include: • Any land use or land use changes that affect points of assessment as a function of time and the timing of hypothetical inadvertent intrusion; and • Citations or reference to relevant documents or agreements serving as the basis for land use and institutional control assumptions. DOE-STD-5002-2017 2-38 Objective Identify and describe land use and institutional control assumptions that form the basis for the selection of the POA as a function of time and also determine when inadvertent intrusion needs to be considered as a possibility. Discussion DOE maintains control over the disposal facility until it can be released in accordance with DOE O 458.1. Nevertheless, for the purposes of the PA, the default assumption is that institutional controls are maintained for 100 years. This section summarizes information on land use in the area of the facility to provide perspective on the likelihood and types of potential exposure scenarios in the area and when and where those exposures could occur. Any formal agreements and regulatory commitments for institutional controls documents specific agreements and commitments for institutional controls that form the basis for assumptions about the timing and location of the POA are also documented. Commitments to institutional controls, industrial land use, etc. should be included here, although it will be necessary to justify their effectiveness in order to consider an extension of the length of time institutional controls can be effective for a PA. There are examples where a combination of documented agreements and expert elicitation have been used to justify an extended period before intrusion can occur, (e.g., roughly another 100 years) but are not expected to preclude the need to address inadvertent human intrusion when developing waste acceptance criteria. Although it is possible to justify the effectiveness of institutional controls beyond 100 years, it is more common that agreements or regulatory commitments are used as a demonstration of added defense-in-depth rather than trying to justify a change in assumptions regarding future exposures. This is different from assumptions for hazardous waste disposal facilities where controls are assumed to be able to be maintained in perpetuity or for remedial actions, where in some cases it is accepted to only allow industrial or other land use that limits the potential exposure scenarios. There also may be situations where extensions of the active institutional control period are mandatory and judicious, for example to provide for continued surveillance and maintenance of the closure cap in cases where settlement/subsidence or other disruptions to the closure cap are a concern for the PA. Example: Site X closed their onsite LLW disposal facility and has performed a final performance assessment and closure plan. The site assumed a 50-year active institutional control period where the site will be fenced in and will have employees that perform periodic inspections of the facility for possible intrusion and for subsidence, drainage, etc. This scenario was evaluated in the PA and the

DOE-STD-5002-2017 2-39 closed site will meet all performance objectives throughout the compliance period. Example: Site Y has closed their onsite LLW disposal facility. The final PA and closure plan has identified an active institutional control period of 125 years. This assumption is based upon a land use plan that is signed by the DOE and agreed to by the State regulators that includes the LLW disposal facility being identified on local government property maps, a fenced that surrounds the facility, permanent markers every fifty yards that identify the area as a radioactive site and DOE personnel actively inspecting the facility on a scheduled basis for intruders. This well documented institutional control plan is included as part of the closure plan. 2.2.2.9 Summary of Key Assumptions This section should summarize the key assumptions in the PA important to projected performance of the disposal facility with specific emphasis on assumptions related to key uncertainties or data gaps that will be addressed as part of the maintenance process or need to be protected in design, operating or closure documents should be included. Assumptions related to design, operations and closure that need to be protected by the facility operators and transferred to the closure and institutional control authority should be identified and communicated to the appropriate organization and captured in designs and operating procedures, as appropriate. Where certain key assumptions are associated with uncertainties or data gaps that will be addressed as part of the PA maintenance process, these assumptions should be presented in such a way that the implications of the uncertainty, approach for managing the uncertainty, and required actions are clearly understood. Significance of these key assumptions should be put in context by explaining relevance to controlling pathways or scenarios analyzed. Objective Identify and describe key assumptions that have the greatest influence on the conclusions of the PA. Specifically identify assumptions that need to be protected in operating, design or closure documentation and assumptions that are being addressed through the PA maintenance process (e.g., to address secondary issues from an LFRG review team). Discussion This section should highlight key assumptions used in the PA that are most critical to the analysis of performance. This could include, for example, the assumed future boundary of land controlled by DOE, assumed design and/or performance of a cover system, or simplifying DOE-STD-5002-2017 2-40 assumptions made to facilitate groundwater flow and transport modeling. The significance of these assumptions should be put into context by explaining their relevance to the controlling pathways or scenarios analyzed, key assumptions, or their use in justifying a point of compliance (i.e., beyond a 100-meter buffer zone surrounding the waste). Certain key assumptions may be associated with uncertainties or data gaps identified in Secondary Issues from an LFRG review that will be addressed as part of the PA maintenance process. These assumptions should be presented in such a way that the implications of the uncertainty and the actions needed to manage the uncertainty are clearly understood. This information can then be readily used to support the PA maintenance process. Specific uncertainties and data gaps that need to be addressed through research and development should be highlighted so they can be documented in the PA/CA MP.

Assumptions related to design, operations and closure that need to be protected by the facility operators and transferred to the closure and institutional control authority should be identified and communicated to that organization and captured in designs and operating procedures, as appropriate. Significance of the assumptions needs to be put in context by explaining relevance to controlling pathways or scenarios analyzed. Examples of key assumptions: • Active institutional control will be maintained for 100 years; • Minimum of 4 feet of native soil will be placed over the waste; • At least 25-feet should be maintained from the bottom of the waste to the aquifer; • No more than 25 Ci of Tritium may be disposed in the facility; and • Only onsite LLW will be accepted for disposal. Site and Facility Characteristics These sections should provide detailed descriptive information and data for the DOE site, the environment, and disposal facility to provide the basis for the conceptual model. Documentation of key site-oriented parameter values used in the models (e.g., precipitation rates) and citations should be provided. Additional emphasis is expected for characteristics that are important drivers for the disposal system performance. Information to support the development of ranges/distributions should be provided or referenced in this chapter. Development of the ranges and/or distributions of input parameters and failure modes/scenarios should be discussed either here or with the discussion of the conceptual and mathematical models. DOE-STD-5002-2017 2-41 A total systems approach, recognizing the interrelationship of site characteristics and the conceptual facility design should be provided. In addition, reasonably foreseeable natural processes (e.g., climate impacts, erosion, subsidence, burrowing animals, etc.) that might disrupt natural and engineered barriers should be addressed. All information sources should be clearly referenced, and significant changes from previous PAs or other modeling efforts should be identified. Objective This Chapter provides the detailed information about the site and disposal facility (natural and engineered features) that form the basis for development of the conceptual models. Uncertainties and potential alternative representations of key components of the system are also described. Discussion This Chapter should provide descriptive information and data for the DOE site, environment, LLW disposal facility, and LLW characteristics to provide the basis for the conceptual model of the disposal facility and site, and to support a thorough understanding of the method of analysis. The information in this section comprises a detailed description including specific sources for data and uncertainties associated with the data, including potential alternative interpretations that may need to be considered. The emphasis of information in this section should be on those characteristics that are important to the performance of the disposal system, the source term models, the transport models, and the dose analysis. The roles of the key features in terms of limiting the eventual impacts of the disposal facility (safety functions, e.g., Nuclear Energy Agency (NEA) 2012, Methods for Safety Assessment of Geological Disposal Facilities for Radioactive Waste – Outcomes of the MeSA Initiative) should be summarized in preparation for the development of conceptual models and scenarios to be considered. The information provided should also be developed with a view towards identifying relevant features, events and processes (FEP) and screening FEP that are not significant. Safety functions and FEP will be considered for the development of the scenarios and conceptual models.

A graded approach should be used to assure that an appropriate level of detail commensurate with the relative importance and quantity and quality of available information is presented. For example, if a PA of a similar facility has previously been performed at the same DOE site, it may be possible to summarize the information and cite the other reports for the detailed description. In any event, the level of detail provided (either directly, in appendices, or references) should be sufficient to allow an independent reviewer to conclude that the site-specific analysis of performance is complete, logical, technically correct, rigorous, and defensible. Probabilistic approaches for the PA or the sensitivity and uncertainty analyses will require distributions for key parameters and may also consider alternative conceptual models. The basis for any distributions provided should be justified, especially considering the quality and DOE-STD-5002-2017 2-42 applicability of the information on which the distribution is based. Often simplified distributions are selected reflecting a lack of information. The potential for risk dilution should be considered when estimating distributions. When developing site and facility characteristics, it is required to address reasonably foreseeable natural processes. The emphasis is placed on identifying processes that are expected to significantly influence the conclusions of the analysis regarding the ability to meet the performance objectives. The term “reasonably foreseeable natural processes” is used to clarify expectations for assessments addressing the long-term evolution of the natural and engineered systems and the ability to maintain releases at acceptable levels. The emphasis of the consideration of natural processes is focused on the 1,000-year period of assessment for comparison with performance objectives. Natural processes that have a significant likelihood of impacting natural or engineered features over that time frame need to be described in the context of the continuing ability for the disposal facility to meet the performance objectives. It is also important to address potential impacts of natural processes in the far future after 1,000 years, but such consideration should be placed in context of the growing uncertainties and speculation associated with human behavior, natural process and broader more catastrophic impacts that are expected to occur in the far future (e.g., glaciation, meteors, etc.). Consideration of natural process should be put in the context of the ability of natural and engineered barriers to continue to fulfill their intended role to provide reasonable expectation that performance objectives will continue to be met. The use of concepts like “safety functions” that has been advocated internationally can help to focus on the specific roles that different barriers need to perform in order for the performance objectives to be met. Understanding the roles that are expected of each barrier in terms of limiting migration helps to focus on how changes in the system could lead to a situation where those roles cannot be fulfilled and potential for compromised performance. The roles of natural processes are captured through the definition of the conceptual model and scenarios for the evolution of the facility. It will be necessary to provide supporting information documenting the basis for the conceptual model and reference and alternative scenarios considered as part of the PA. A graded approach is recommended where the level of detail in a conceptual model may be more simplified at the start of the process and refinements are added in areas that are deemed important for the conclusions of the analysis that support decision-making.

As PAs will be updated as part of the maintenance process, it is very important that all sources of information presented in this section be clearly referenced (page, section, and table/figure specific references), including the date of the information. This will help assure that updates incorporate the most recent data. DOE-STD-5002-2017 2-43 2.2.3.1 Site Characteristics The Site Characteristics subsections should: • Include the relevant natural and demographic characteristics and data for the disposal site and surrounding area in sufficient detail to provide a basis for the conceptual model of the site- and facility-behavior; • Address reasonably foreseeable natural events that might disrupt barriers (e.g., severe storms, tornados, and seismic events); • Highlight key parameters and assumptions and provide information to serve as a basis for development of ranges/distributions to support consideration in the sensitivity/uncertainty analysis and incorporate into the PA maintenance activities, as applicable; and • Provide a brief explanation of how the information is used in the PA. 2.2.3.1.1 Geography and Demographics, Populations, Use of Adjacent Lands Describe the regional setting for the DOE site and the disposal facility (e.g., distance and direction to nearby towns, rivers, or other natural or man-made landmarks). A site map clearly indicating the regional setting, the boundaries of existing or proposed disposal site, and the future boundary of DOE controlled land should be included. Any planned or expected need for expansion of the disposal facility should be described to the extent necessary for a reviewer to understand the analysis of site performance. Site Description. Provide a general description of the disposal facility and surrounding area including the physical area, actual disposal facility, general vegetation type, topography, and location relative to nearby bodies of water, roadways, or other landmarks. Include any nearby features that are potentially significant relative to the long-term performance of the facility (e.g., nearby dams). Population Distribution. Present existing and projected area populations to support the land use plans related to the site and specification of the POA included in the PA. Use of Adjacent Lands. Summarize relevant historical and current land uses in the vicinity of the disposal facility. Emphasize predominant uses that could potentially impact assumptions regarding performance of the facility (e.g., large scale irrigation changing recharge or aquifer assumptions) and any relevant uses that could be adversely affected by releases of contaminants from the disposal facility. DOE-STD-5002-2017 2-44 2.2.3.1.2 Meteorology and Climatology Provide a general description of regional and site-specific climatological conditions, with an emphasis on local meteorology and microclimate, in sufficient detail to support the conceptual model for the disposal facility and associated modeling of site performance. This section should serve as the basis for assumptions related to precipitation and natural recharge, which are generally a significant consideration for a PA. Ranges and distributions of precipitation and recharge data should be discussed. Information to serve as the basis for development of ranges and distributions that would be used in the PA should also be provided or citations should be included for more details. Examples of how changes in precipitation and recharge (e.g., natural cycles, climate change) have been addressed is available in existing PAs and additional information on climate change can be found at www.climate.org.

If necessary to support assumptions, the relationship between regional atmospheric conditions and local meteorological conditions should be described. Include any interpretations of data for defining parametric values used in the PA or provide reference to another section/appendix where this information is provided. Include a brief discussion of the data on which meteorological and climatological characterization are based, including locations of meteorology stations and duration of data collection. To the extent practical, the PA should assess the potential impacts of reasonably foreseeable natural phenomena that could impact the facility (e.g., tornadoes, storms, water or wind erosion, freeze-thaw) and longer-term climate change (e.g., increased storm frequency, changes in average precipitation and groundwater levels) and identify opportunities to incorporate principles of sustainability into waste facility design and operation. Potential impacts on groundwater levels and flow directions and rates resulting from significant changes in precipitation also need to be addressed. 2.2.3.1.3 Ecology Provide relevant information derived from existing site surveys, environmental impact statements, or other analyses concerning plant and animal species and communities important to long-term performance of the disposal facility, including burrowing insect or mammal populations, major plant communities, or vegetation types influencing cover performance. This information should include reasonably foreseeable long-term changes in biological processes. 2.2.3.1.4 Geology, Seismology, and Volcanology Provide relevant information on the geologic, seismic, and volcanic characteristics of the site and the region in sufficient detail to support the conceptual model and the performance analysis. Provide applicable information on the history and frequency of regional natural processes and phenomena that are reasonably foreseeable (e.g., earthquake frequency, volcanic eruptions). DOE-STD-5002-2017 http://www.climate.org/ 2-45 2.2.3.1.5 Hydrology Data and results of technical analyses that describe the surface and groundwater hydrology of the site and vicinity in sufficient detail to support the conceptual model and the performance analysis should be presented. Include descriptions of existing surface and groundwater users and community water systems near the facility and planned future development of water resources. Surface Water. Provide characterization of disposal site drainage and the surrounding watershed, including topographic maps showing elevations and relevant system features, natural drainages, and man-made features. Describe the location, size, shape, and other hydrologic characteristics of relevant surface water bodies near the site, including sources of potable water. Vadose Zone and Aquifer. Provide relevant information, including uncertainties, that describes the hydrogeologic setting to be used in the development of the conceptual model and the performance analysis. Known factors that result in changes to the migration of groundwater over time should also be identified (e.g., existing high points in an aquifer resulting from previous operations that are decreasing over time). Provide the direction and velocity of unsaturated flow, total and effective porosity, hydraulic conductivity, specific retention and relative permeability relationships, saturated hydraulic conductivity, and volumetric water content sufficient to support the conceptual model, including references and sources of information used in modeling (e.g., monitoring wells and boreholes at or near the disposal site.)

Provide data describing the saturated zone including lateral extent and thickness, flow directions and velocities, effective and total porosity, saturated hydraulic conductivity, and storativity (storage coefficient) for each potentially affected aquifer sufficient to support the conceptual model. Include sources of information used in development of groundwater modeling. Include existing concentrations of radionuclides in groundwater, if relevant to the water resources impact assessment. 2.2.3.1.6 Geochemistry Applicable background information and data to support the geochemical assumptions and conceptual model should be presented. Include information and data describing the water chemistry and geochemistry for the surface and subsurface environment at the disposal facility. Include significant physical parameters (e.g., temperature) and chemical data such as pH, dissociation constants, oxidation/reduction characteristics, and concentrations of inorganic and organic constituents necessary to support the conceptual model. Include information characterizing the significant chemical features of soils and rock units at the disposal site to support the conceptual model of the facility and the modeling of the facility performance. DOE-STD-5002-2017 2-46 2.2.3.1.7 Natural Resources Describe current or reasonably foreseeable exploitation of natural resources in the vicinity that impact the conceptual model of the facility and any related assumptions in the analysis of performance. Provide a description of any economically valuable natural resources, their location, the degree of current or potential exploitation, and the potential impacts on the facility. Geologic Resources. Provide a description of location and extent of ores, fuels (e.g., coal), hydrocarbons (e.g., gas, oil), industrial mineral deposits (e.g., sand, gravel, clay, building stone), geothermal resources, and any other significant resources in the area of the site that would affect the analysis of performance. Provide current and projected use estimates including at least a qualitative discussion of economic value and feasibility of recovery. Water Resources. Provide data on use of surface and groundwater in the area that may be affected by the site. Provide relevant features of typical well construction in the region, drilling methods, dimensions, to support development of intrusion scenarios. Present anticipated effects of water use relevant to the conceptual model of the facility and associated modeling of site performance. 2.2.3.1.8 Natural Background Radiation Present concise summary of relevant natural environmental radiation from facility and surrounding area. Objective This section provides the detailed information about the site and natural system that form the basis for development of the conceptual models. Discussion This section of the PA should present the relevant natural and demographic characteristics and data for the disposal site and surrounding area. The safety functions of the different features should be introduced with any insights as to the relative significance in the context of the total system, as applicable (e.g., sorption, dispersion and dilution in groundwater, delay and dispersion in the vadose zone). The use of the concept of safety functions tends to be more clear and relevant for engineered features, but the general intent is to identify expected roles of the natural system in reducing potential impacts at a receptor. The other component is associated with FEP. The discussion for each area should also consider potential factors (e.g., FEP) that could impact the effectiveness of a safety function. For example, recharge rates could increase or decrease, thus impacting assumptions about the timing of migration through the system (positive or

DOE-STD-5002-2017 2-47 negative effect). The level of detail included in this section should be sufficient to provide a basis for the conceptual model of the site and facility behavior, and the modeling assumptions made in the performance analysis and details may be provided in supporting documentation. The presentation of the site characteristics should provide sufficient information to allow an independent reviewer to conclude that the site-specific analysis of performance that follows is complete, logical, technically correct, rigorous and defensible. For proposed facilities, the site characteristic information should sufficient to support the site evaluation process and should be coordinated with NEPA or other regulatory analyses. This guide specifies the primary site characteristics that should be evaluated in the process of establishing a new LLW facility so that the features of the site can be thoroughly understood, that a determination can be made that the site is suitable to support the facility, and so relevant features of the site can be appropriately balanced with considerations for the facility design. The presentation of site characteristics should also include identification of uncertainties associated with the information and data presented. Uncertainties and alternative interpretations should be highlighted so that they can be evaluated in the sensitivity/uncertainty analysis and, as appropriate, incorporated into the PA maintenance and research and development planning and implementation processes. Additional guidance is provided below for specific subsections. Geology. The structural geology of the region should be described, and its relationship to the disposal site geologic structure should be discussed to provide the basis for the conceptual model of the disposal facility and the modeling of the disposal facility. Any relevant features, such as faults, folds, open jointing, fractures, or shear zones in the region should be identified, and their significance to the projected long-term performance of the disposal facility should be discussed. Maps and geologic profiles should be presented to supplement the descriptive language. In addition to supporting the analysis of performance, identification of any existing or potential disposal site conditions that could compromise the ability of the disposal site to fulfill the required performance objectives should be presented in this section. This includes significant topographical features and the surface and subsurface geologic characteristics of the disposal site and its vicinity, such as soil characteristics, mineralogy, particle size, organic materials, degree of cementation, zones of alteration, and depositional environment of unconsolidated strata. Reasonably foreseeable processes such as mass wasting, erosion, slumping, land sliding, and weathering should also be described as necessary to support conceptual model and the analysis of performance. Any applicable results from geotechnical engineering studies conducted at or near the disposal site should also be summarized and referenced. Seismology. Relevant information describing all known or inferred faults in the disposal site vicinity that could potentially affect waste isolation should be described. Graphical presentation of the relationship of seismic features to the disposal facility should be included, as appropriate. DOE-STD-5002-2017 2-48 The relationship of these faults to the present-day local stress field should be described, as well as any potential effects on the disposal site as a result of fault displacement. This section should also provide applicable information on the seismological investigations that have been or are to be carried out at the di