The Safety Case and the Risk-Informed Performance-Based Approach for Management of US Commercial Low-Level Waste (Paper #190)

Transcription

1 The Safety Case and the Risk-Informed Performance-Based Approach for Management of US Commercial Low-Level Waste (Paper #190) Rateb (Boby) Abu-Eid, David Esh, and Christopher Grossman Division of Decommissioning, Uranium Recovery, and Waste Management Programs Office of Nuclear Material Safety and Safeguards United States Nuclear Regulatory Commission IAEA International Conference on Safety of Radioactive Waste Management November 21-25, 2016 Vienna, Austria

2 Disclaimer Note Certain materials in this presentation involves ongoing amendments of 10 CFR Part 61 and implementation final draft technical guidance document (NUREG-2175). We note that the final provisions of 10 CFR Part 61 amendment and the final draft NUREG-2175 are currently subject to Commission review and approval.

3 Stakeholder and Regulatory Involvement IAEA Safety Case Components (IAEA SSG-23) A. Safety Case Context B. Safety Strategy E. Iteration and Design Optimization C. System Description D. Safety Assessment G. Limits, Controls and Conditions H. Integration of Safety Arguments F. Management of Uncertainty Application of Management System 3

4 US Presidential/Congressional Commission on Risk Assessment & Risk Management, 1997 US GAO Risk Management Framework, 2005 A, B A,B C, E D, H D, F,G E, F G, H C,E

5 NRC Risk-Informed Performance-Based Regulations The NRC developed a Probabilistic Risk Assessment (PRA) Implementation Plan (1994). This plan was superseded in 2000 by the Risk-Informed Regulation Implementation Plan (RIRIP). Many of the NRC regulations were based on deterministic and prescriptive requirements. US Low-Level Waste (LLW) regulations under 10 CFR Part 61, developed in 1980 s, were based on risk (dose) to members of the public, risk to inadvertent intruder, and disposal site performance. In April 2007, the NRC replaced the RIRIP with the Risk-Informed, Performance-Based Plan (RPP). Each of these plans has guided the NRC in developing risk-informed performance-based regulations and implementation guides. Currently, the NRC is amending its regulations that govern low-level radioactive waste disposal facilities to require new and revised site-specific technical analyses (Federal Register /Vol. 80, No. 58 /Thursday, March 26, 2015). 5

6 Technical Analysis Techniques and Deliberation (NUREG-2150) 6

7 Aspects of Safety Case in NUREG-2175 Strategy for Achieving Safe Disposal of Radioactive Waste; Description of the Disposal Site and Facility; Description of the Technical Analyses; Demonstrating Performance Objectives; Strategy for Institutional Control of the Disposal Site; Description of Financial Qualifications of the Licensee; Description of Other Information; and Safety Arguments/Functions.

8 Revised Part 61 Overview Safety case and defense-in-depth protections; Site-specific technical analyses (performance assessment, intruder assessment, site-stability); Time of compliance considering waste characteristics; Site-specific intruder receptors; Waste acceptance criteria may be developed based on the results of the technical analyses; Updated dose methodologies; Consideration of uncertainty; Model support; and Site characteristics consider waste characteristics and are riskinformed, performance-based. 8

9 10 CFR Part 61 Acceptance Criteria Example: Waste Acceptance Criteria Allowable Radioactivity Limits Acceptable Waste Form Characteristics and Container Specifications Restrictions and Prohibitions Allowable Limits on Radioactivity Waste form Characteristics and Container Specifications Restrictions and Prohibitions 9

10 Example: Defense-in-Depth The use of multiple, independent, and, where possible, redundant layers of defense so that no single layer, no matter how robust, is exclusively relied upon. Identify defense-in-depth protections commensurate with risks. Describe capabilities of defensein-depth protections. Provide a technical basis for capabilities of defense-in-depth protections. Note: Lifecycle timeframes not to scale 10

11 Summary/Conclusion Safety Case & 10 CFR Part 61 Safety Case is an integrated approach to risk assessment and risk management. NRC staff explicitly added the safety case concept in the ongoing amendment of 10 CFR Part 61, at the direction of Commission. Plain language description the safety arguments and evidence to demonstrate the overall safety of a land disposal facility were developed. It describes all safety relevant aspects of the disposal site, the design of the facility, and the managerial control measures and regulatory controls to inform the decision whether to grant a license. It includes the same type of information that the original 10 CFR Part 61 required to be submitted as part of a license application (i.e., 10 CFR CFR 61.16). The safety case will be updated over time as a new information is gained during the various phases of the facility s development, inspection, and operation. 10 CFR Part 61 SC is quite consistent with IAEA SSG-23 with more detailed technical analysis. 11

12 BACK-UP SLIDES

13 Timeframes Waste specific 13

14 US Ecology, Hanford, WA Who will perform these Technical Analyses? Commercial LLRW Sites in U.S. Richland, Washington Facility Waste Compact Restrictions Richland, WA A, B, C 11 Western states in 2 LLW Compacts only Clive, UT A only None, all US generators OK (Compacts must approve) EnergySolutions, Clive, Utah Waste Control Specialists, Andrews, TX Energy Solutions, Barnwell SC Operating facility Barnwell, SC A, B, C SC, NJ, CT only (Atlantic Compact) Andrews Cty, Texas A, B, C Texas and VT (Texas Compact), Others with Compact approval 5

15 Normal Activities Dwelling Construction Agriculture Drilling for Water 15

16 Site-specific Scenarios - Guidance Constrain exposure pathways for normal or reasonably foreseeable activities based on: Physical information Waste characteristics and disposal practices Disposal site characteristics Cultural information (e.g. land use) Provide comparison of results from site-specific scenarios to generic scenarios. 16

17 Site Stability - Guidance 17

18 Waste Acceptance Requirements Licensees must review their waste acceptance program at least annually Ensures that the program continues to be adequate and is being implemented in a way that continues to protect public health and safety 18

19 NUREG-2175 NUREG-2175 (Guidance for Conducting Technical Analyses for 10 CFR Part 61) provides: Flowcharts, NRC staff recommendations, and examples for how licensees can develop high-quality technical analyses Guidelines for what licensees or applicants should include and what regulators should review for each type of analysis Suggested references, screening tools, and case studies DRAFT final version made publically available in ADAMS and on the public website 19