ML23045A286
| ML23045A286 | |
| Person / Time | |
|---|---|
| Issue date: | 03/14/2023 |
| From: | Mike Franovich Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| Download: ML23045A286 (1) | |
Text
Advances in RIDM: Past, Present, Future Technical Session T5 Michael X. Franovich Director, Division of Risk Assessment Office of Nuclear Reactor Regulation
Agenda History of Risk-Informed Decision-Making Risk-Informed Guidance Development/A Graded Approach International Cooperation LIC-504: High Energy Arcing Faults Emergency Planning Zone Sizing - SMRs 2
GL-88-20, Individual Plant Examination WASH-740 §50.62 (IPE) for Severe ATWS Rule Accident Safety Goal Policy Vulnerabilities, Statement NUREG-1560 Three Mile §50.63 SBO Island Rule 1957 1975 1978 1979 1984 1985 1986 1988 Chernobyl WASH-1400 The Reactor NUREG-0396 Safety Study Emergency NUREG-1150 Response Plans Severe Accident Policy Statement
- Not to Scale 3
GL-88-20, Vol. 9-11 Attacks 4, IPE for RIDM External Events Initiatives SECY 98-144, Risk- RG 1.200 Informed PRA Performance Acceptability
§50.65 Based Regulation Maintenance Rule 1991 1995 1998 2001 2004 2011 2017-Present Fukushima Daiichi PRA Policy Statement RG 1.174 NTTF Flooding Key Principles NTTF Seismic
- Not to Scale 4
Risk-informed Operating Reactor Programs Have Informed New and Advanced Reactor Guidance Development (A Graded Approach) 10 CFR 50.69 Risk-Informed Categorization NuScale SSC Classification RISC-I: Safety-Related, Safety Significant A1: Safety-Related, Risk-Significant RISC-II: Nonsafety-Related, Safety Significant A2: Safety-Related, Not Risk-Significant LMP Safety Classification RISC-III: Safety-Related, Low Safety Significant B1: Nonsafety-Related, Risk- Safety-Related Significant Non-Safety-Related with RISC-IV: Nonsafety-Related, Low Safety Significant B2: Nonsafety-Related, Not Special Treatment Risk-Significant Non-Safety-Related with No Special Treatment 5
NRC International Strategy Advance risk management concepts through international standards and guidance for graded approaches in licensing and oversight of operating and new reactors IAEA No. SSR-2/1, Safety of Nuclear Power Plants: Design IAEA No. SSG-3, Development and Application of Level 1 Probabilistic Safety Assessment for Nuclear Power Plants IAEA TECDOC-1980, Application of a Graded Approach in Regulating Nuclear Installations 6
LIC-504: Integrated Decision-Making Process for Emergent Issues
- Developed as a lessons learned from Davis-Besse reactor vessel head degradation
- Provides a structured process to document decisions for issues that may warrant prompt regulatory actions
- Provides guidance to apply integrated decision-making including risk, defense-in-depth, and safety margins considerations
- Has been used frequently for a range of emergent plant-specific and generic issues 7
LIC-504 Graded Recommendations - examples Spectrum of Regulatory Options 10-3 Immediate regulatory action Formal backfit analysis ( 10-4 )
10-4 Change in CDF 50.54(f) letters 10-5 Bulletin Information Notice/Outreach 10-6 Smart inspection samples 10-7 No Actions Regulatory Intensity Use RIDM - Not numbers alone 8
LIC-504: High Energy Arcing Faults (HEAF) 2007-2008: First international examination 2013: NEA/OECD FIRE program
- HEAFs are often risk significant with complicated shutdowns 2014-2016: International Test Program
- NRC observed potential for new failure mechanisms and larger damage states 2021: Integrated Decision-Making Process for Emergent Issues
- NRC used the LIC-504 process for disposition using new methods
- Risk Insights Informed NRC Actions
- Final Regulatory Decision - no new requirements
- Extensive Outreach to Stakeholders: public webinar, industry forums, and NRC Information Notice (pending)
- Incorporation of Insights into NRC Oversight Activities 9
RIDM in Emergency Planning Zone Sizing Emergency Planning Zones (EPZs) Drivers for Risk-Informed EPZ Sizing
- EPZ = area within which prompt
- Maturity of PRA technical protective actions may be acceptability guidance necessary in the event of a
- Different risk profile compared radiological release to operating reactors
- NRC regulation on size of plume
- Emergency Plans for 10-mile exposure pathway: EPZ can include many states,
- 10 miles for light- counties, townships, schools, water reactors >250 MWth hospitals, Coast Guard,
- Case-by-case evacuation plans, emergency basis for reactors <250MWth drills, etc.
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Conclusions from Risk-Informed Approach for Emergency Planning Zone Sizing (SMRs)
- Novel approach provides regulatory stability
- Provides design- and site-specific seismic screening threshold value(s) consistent with technical basis in NUREG-0396
- Results in a complete spectrum of accidents and avoids extremely unlikely seismic accelerations
- Addresses multi-module risk
- Uses quantified seismic sequences because they can be dominant contributor to plant risk and EPZ sizing
Key Messages NRC supports and advances risk-informed decision making (RIDM) through its programs and activities to help enhance safety and focus resources on what is most safety significant. Additional opportunities exist for future initiatives.
NRC is leveraging the use of risk assessment approaches in RIDM in a manner that complements Defense-in-Depth, Safety Margins, Engineering Judgment, and Enterprise Risk.
The NRC has built a strong foundation in risk-informed guidance and tools and is continuing to develop innovative approaches, including leveraging international cooperation, to increase the use of risk-informed decisionmaking.
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Technical Session T5 Building on a Strong Foundation: A Voyage through Risk Informed Decision-Making Advances in RIDM: Past, Present, Future Points of Contact Stacey.Rosenberg@nrc.gov Senior Reliability and Risk Analyst Division of Risk Assessment, NRR Alissa.Neuhausen@nrc.gov Reliability and Risk Analyst Division of Risk Assessment, NRR 13
Acronyms CDF Core Damage Frequency LERF Large Early Release Frequency LMP Licensing Modernization Project NTTF Near Term Task Force SSC Structures, Systems, Components SMR Small Modular Reactor