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 Integrated Decisionmaking (RG 1.174)
- 2. Change is consistent with defense-in-depth (DiD) philosophy.
- 3. Maintain sufficient safety margins.
- 4. Proposed increases in CDF or risk are small and are consistent with the Commissions Safety Goal Policy Statement.
- 5. Use performance measurement strategies to monitor the change.
- 1. Change meets current regulations unless it is explicitly related to a requested exemption or rule change.
Risk/PRA Analysis NRR/DRA Deterministic Review NRR/DE, NRR/DSS 6
Level of PRA Acceptability Depends on the Application Risk-Informed Inservice Inspection 50.69 SSC Categorization 5b, Risk-Informed Surveillance Frequencies NFPA-805, Risk-Informed Fire Protection 4b, Risk-Informed Completion Times Acceptability Required scope, level of detail, technical elements, and plant representation Greater reliance on PRA More flexibility for licensee More complex staff review 7
Source: 2013 letter from Nuclear Energy Institute (NEI) to NRC (ML13354B997)
Internal Events Internal Flooding Internal Fire No 10%
No 7%
No 37%
Yes 90%
Yes 93%
Yes 63%
Seismic, High Winds, or External Flooding Are models across the fleet peer-reviewed?
Yes 46%
No 54%
Industry PRA Models Have Improved Greatly Over the Last Decade 8
Risk-Informed Licensing is Trending Upward:
0 30 60 90 120 150 FY14 FY15 FY16 FY17 FY18 Other Tornado Missile NFPA-805 50.69 S-PRA GSI-191 TSTF-425 TSTF-505 ILRT Submittal Number Risk-Informed Submittals Under Review 9
- Reactor Coolant Pump (RCP) seals
- Additional feed water pumps
- Alternate RCP seal injection
- New diesel generators Risk Insights Gained from Fire PRA Are Driving Safety Improvements
- 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
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)
Risk-Managed Technical Specifications 12
NRC Continues to Review Implementation of Surveillance Frequency Control Program 5b Available New Frequencies 24 Hrs 3 Days 7 Days 31 Days 92 Days 6 Months 18 Months TSTF-425 and NEI-04-10
- Adopted by ~ 75% of industry (Vogtle 2012)
- IP 71111.22, Surveillance Testing - Appendix A 13
NRC is Prepared for Increased LARs for T/S 4b R - Risk I - Informed C - Completion T - Times Existing TS Completion Time Frontstop Risk-Informed Completion Time (RICT) Limit Backstop Component Inoperable 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 15 Design Basis Risk-Informed
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).
NFPA-805 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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