ML19274C668
| ML19274C668 | |
| Person / Time | |
|---|---|
| Issue date: | 10/01/2019 |
| From: | Michael Levine NRC/NRR/DRA/APLA |
| To: | |
| RAKOVAN L/NMSS/MSST | |
| Shared Package | |
| ML19274C654 | List: |
| References | |
| Download: ML19274C668 (21) | |
Text
Risk-Informed Licensing Initiatives Michael Levine, Reliability and Risk Analyst, NRR/DRA
Purpose
- Purpose
- Introduce state liaisons to the risk-informed decision-making
- Introduce state liaisons to the NRC risk-informed licensing initiatives.
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Outline
- Outline
- Overview of risk-informed decision making (RIDM)
- Fire PRA Risk Insights
- TSTF-425: risk-informed surveillance frequencies (5b)
- Technical Specifications Task Force (TSTF) 505:
risk-informed completion times (4b)
- 50.69: risk-informed structure, system, or component (SSC) categorization 3
Risk-Informed Decision-Making
- SECY 17-0112, Plans for Increasing Staff Capabilities to Use Risk Information in Decision-making Activities (ADAMS ML17270A197)
- Affirms Commission direction in SRM-M170511
- Provides multi-faceted approach to address challenges
- NRC uses risk information in areas of:
- Regulations & Guidance
- Licensing & Certification
- Oversight
- Operational Experience 4
Related Guidance 5
Risk-Insights Are Just One Component of Integrated Regulatory Decisionmaking
- 2. Change is consistent with defense-in-depth Deterministic Review (DiD) philosophy.
NRR/DE, NRR/DSS
- 1. Change meets current regulations unless it is explicitly 3. Maintain sufficient related to a safety margins.
requested exemption Integrated or rule change.
Decisionmaking (RG 1.174)
- 4. Proposed increases in CDF or Risk/PRA 5. Use performance risk are small and are measurement Analysis strategies to monitor consistent with the Commissions Safety NRR/DRA the change.
Goal Policy Statement.
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Level of PRA Acceptability Depends on the Application 4b, Risk-Informed Completion Times NFPA-805, Risk-Informed Fire Acceptability Protection
- Greater reliance on Required scope, PRA level of detail,
- More flexibility for technical 50.69 SSC Categorization licensee elements, and
- More complex staff plant review representation 5b, Risk-Informed Surveillance Frequencies Risk-Informed Inservice Inspection 7
Industry PRA Models Have Improved Greatly Over the Last Decade Seismic, High Winds, Internal Internal Internal or External Flooding Events Flooding Fire No No 10% 7% No 37% Yes No Yes 46% 54%
Yes Yes 63%
90% 93%
Are models across the fleet peer-reviewed?
Source: 2013 letter from Nuclear Energy Institute (NEI) to NRC (ML13354B997) 8
Risk-Informed Licensing is Trending Upward:
Risk-Informed Submittals Under Review 150 Other Tornado Missile NFPA-805 50.69 S-PRA GSI-191 120 Submittal Number TSTF-425 TSTF-505 ILRT 90 60 30 0
FY14 FY15 FY16 FY17 FY18 9
Risk Insights Gained from Fire PRA Are Driving Safety Improvements
- Reactor Coolant Pump (RCP) seals
- Additional feed water pumps
- Alternate RCP seal injection
- New diesel generators
- Improved batteries
- Traditional fire protection equipment (shielding, detection, etc.)
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Several Major Risk-Informed Initiatives Are Under Review
- Technical Specifications Task Force (TSTF) 425:
risk-informed surveillance frequencies (5b)
- TSTF-505: risk-informed completion times (4b)
- 50.69: risk-informed structure, system, or component (SSC) categorization 11
Risk-Managed Technical Specifications
- Technical Specification (TS) define:
- Equipment allowed outage time (AOT) or completion time (CT)
- Frequency of surveillance requirement (SR) testing to verify operability
- Originally defined without benefit of risk insights
- Configuration risk analysis required by 10CFR50.65 (maintenance rule)
- Identifies TS allowable configurations of high risk
- Risk insights can provide basis for modifying various aspects of tech specs
- Extensions (e.g., extending TS CT from 3 to 7 days)
- TSTF-425: risk-informed surveillance frequencies (5b)
- Technical Specifications Task Force (TSTF) 505: risk-informed completion times (4b) 12
NRC Continues to Review Implementation of Surveillance Frequency Control Program 5b
- Adopted by ~ 75% of industry (Vogtle 2012)
- IP 71111.22, Surveillance Testing - Appendix A Available New Frequencies 24 Hrs 3 Days 7 Days 31 Days 92 Days 6 Months 18 Months 13
NRC is Prepared for Increased LARs for T/S 4b R - Risk I - Informed C - Completion T - Times Risk-Informed Existing TS Completion Time Component Completion Time (RICT) Limit Inoperable Frontstop Backstop RICT Limit Risk Management Actions 14
50.69 A Voluntary Alternative Risk-Informed Rule
- Determine safety significance of SSCs
- Modify special treatment requirements for low safety significance SSCs
- Safety significance of SSCs is established based on NRC approved risk-informed categorization process Risk-Informed Design Basis 15
Benefits of 50.69
- Provides incentive for licensees to develop and maintain quality PRA
- Focuses NRC and licensee attention on safety significant activities
- Estimated savings of $1.5M/year/unit(1)
- Establishes better consistency between regulatory requirements and reactor oversight process
- Industry anticipates all plants will provide submittals over the next serval years
- May offer other regulatory benefits (e.g., 10CFR50.59)
- 1. WOG 2003 Study. See ML041470460 16
Conclusions & Observations
- Risk-informed, performance-based regulations continue to shape nuclear plant improvements
- Risk models have improved greatly over the last decade
- Enhanced review guidance and office procedures place greater emphasis on using risk insights
- Greater collaboration between PRA specialists and traditional reviewers
- Focusing on risk significance can result in more streamlined and efficient licensing reviews 17
Summary
- It is Commissions Policy that use of risk information be increased in regulatory matters
- NRC uses risk information in areas of:
- Regulations & Guidance
- Licensing & Certification
- Oversight
- Operational Experience
- PRA models provide useful risk perspectives, which can and should be blended with deterministic input 18
Questions?
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References:
NRC Guidance on Risk-Informed Decisionmaking
- RG 1.174. An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions of Plant-Specific Changes to the Licensing Basis RG 1.174, Rev. 2. (ADAMS Accession No. ML100910006).
- RG 1.175. An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing (ADAMS Accession No. ML003740149).
- RG 1.177, Rev. 1. An Approach for Plant-Specific, Risk-Informed Decision Making: Technical Specifications (ADAMS Accession No. ML100910008).
- RG 1.178. An Approach for Plant-Specific Risk-Informed Decisionmaking for Inservice Inspection of Piping (ADAMS Accession No. ML032510128).
- RG 1.200, Rev. 2. An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities (ADAMS Accession No. ML090410014).
- RG 1.201, Rev.1. Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to Their Safety Significance (ADAMS Accession No. ML061090627).
- RG 1.205, Rev. 1. Risk-Informed, Performance-Based FP for Existing Light-Water Nuclear Power Plants.
(ADAMS Accession No. ML092730314).
- Draft RG 1.1229. Risk-Informed Approach for Addressing the Effects of Debris on Post-Accident Long-Term Core Cooling.
(ADAMS Accession No. ML15023A025).
- NUREG 0800, Section 19.2. Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis: General Guidance (ADAMS Accession No. ML071700658).
- NUREG 1855, Rev. 1. Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decision Making (ADAMS Accession No. ML17062A466).
- NUREG 2201. Probabilistic Risk Assessment and Regulatory Decisionmaking: Some Frequently Asked Questions (ADAMS Accession No. ML16245A032).
- NUREG 2150. A Proposed Risk Management Regulatory Framework (ADAMS Accession No. ML12109A277).
- NUREG/CR-6850, EPRI-NRC RES Fire PRA Methodology for Nuclear Power Facilities, Vol. 1: Summary & Overview (ADAMS Accession No. ML15167A401).
- NUREG/KM-0009. Historical Review and Observations of Defense-in-Depth (ADAMS Accession No. ML16104A071).
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References:
Industry Guidance on Risk-Informed Licensing Actions/Initiatives TSTF-505: Risk-Informed Completion Times (4b)
- NEI 06-09, Rev. 0-A. Risk-Informed Technical Specifications Initiative 4b: Risk-Managed Technical Specifications (RMTS) Guidelines. May 17, 2007 (ADAMS Accession No. ML12286A322).
TSTF-425: Risk-Informed Surveillance Frequencies (5b)
- NEI 04-10, Rev. 1-A, Risk-Informed Technical Specifications Initiative 5b: Risk-Informed Method for Control of Surveillance Frequencies. September 19, 2007 (ADAMS Accession Nos. ML071360425 and ML072570267).
50.69: Risk-Informed SSC Categorization
- NEI 00-04, Rev. 0, 10 CFR 50.69 SSC Categorization Guideline. July 2005 (ADAMS Accession No. ML052910035).
- NEI 04-02, Rev. 2. Guidance for Implementing a Risk-Informed, Performance-Based Fire Protection Program Under 10 CFR 50.48(c). April 2008 (ADAMS Accession No. ML081130188).
Industry PRA Peer Review Guidance
- NEI 00-02, Rev. A3. Probabilistic Risk Assessment Peer Review Process Guidance. March 20, 2000.
PRA Standard
- ASME/ANS RA-Sa-2009. American Society of Mechanical Engineers/American Nuclear Society RA-Sa-2009, Standard for Level 1/Large Early Release Frequency Probabilistic Risk Assessment for Nuclear Power Plant Applications. February 2, 2009.
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