ML19045A528
| ML19045A528 | |
| Person / Time | |
|---|---|
| Issue date: | 02/14/2019 |
| From: | Anders Gilbertson NRC/RES/DRA/PRB |
| To: | |
| A. Gilbertson 415-1541 | |
| References | |
| Download: ML19045A528 (17) | |
Text
NRC Liaison Report Risk-Informed Activities Anders Gilbertson Office of Nuclear Regulatory Research Division of Risk Analysis American Society of Mechanical Engineers/American Nuclear Society (ASME/ANS) Joint Committee on Nuclear Risk Management (JCNRM) Meeting February 14, 2019
Overview
- NRC Risk-Informed Activities Update
- ASME/ANS PRA Standards
- Industry Guidance NRC Liaison Report Risk-Informed Activities 2
February 14, 2019
- Adoption of 10 CFR 50.69 focuses NRC and licensee attention on safety significant activities
- NRC has resources available for 10 reviews/year for completion within 12 months of submission
- NRC has 10 LARs in house and three additional near-term submittals are expected
- NRC has recently accepted 50.69 LARs on a 15-month review schedule due to resource limitations and receiving more LARs than originally anticipated and/or with the inclusion of external events models
- To date, 20 LARs submitted; 16 accepted for NRC review; several audits conducted, more audits planned
- Industry anticipates most plants will submit LARs in the next several years
- Potential obstacles for of reviews
- LARs that follow industry template and have acceptable PRAs require less time and resources for NRC review
- These LARs are the first wide scope use of NUREG-1855 and specific, acceptable dispositions to identify non-key-assumptions need to be developed NRC Liaison Report Risk-Informed Activities 3
February 14, 2019
Risk-Managed Technical Specifications
- Risk insights can provide basis for modifying various aspects of TS
- Fixed extensions (e.g., extending TS completion times from 3 to 7 days)
- TSTF-505: risk-informed extended TS completion times program (RITSTF Initiative 4b)
- TSTF-425: risk-informed surveillance frequencies program (RITSTF Initiative 5b)
- Suspension on use of TSTF-505 lifted in late-2018 with issuance of NRCs final model safety evaluation approving TSTF-505, Revision 2 (ML18253A085)
- NRC continues to review implementation of the TSTF-425 surveillance frequency control program
- Adopted by ~75% of industry
- Inspection Procedure 71111.22, Surveillance Testing - Appendix A NRC Liaison Report Risk-Informed Activities 4
February 14, 2019
Newly Developed PRA Methods
- NRC staff participated in three small PWROG workshops from late-2018 to early-2019
- Workshops have been successful and efficient in addressing issues
- Developed definitions of terms including a formal definition for the term newly developed method
- Developed criteria for peer review of a newly developed PRA method
- The peer review criteria for a newly developed PRA method are requirements that belong in the PRA standard, not in a guidance document
- Process for NRC to accept newly developed methods for use in risk-informed changes to the licensing basis is under development NRC Liaison Report Risk-Informed Activities 5
February 14, 2019
Fire PRA Realism
- Industry expressed that improvements in fire PRA realism are necessary to support risk-informed regulatory applications
- NRC is supporting efforts to look for additional ways to improve the realism of fire PRA
- Evaluation of suitability for incorporating some FAQs into existing research program
- NRC continues to work with EPRI on a spectrum of projects in fire PRA under the joint MOU NRC Liaison Report Risk-Informed Activities 6
February 14, 2019
Crediting Mitigating Strategies in RIDM
- Licensees have requested credit for FLEX strategies in a number of areas beyond compliance with beyond design basis external events (e.g. SDP, LARs, NOEDs)
- Inclusion of FLEX into current risk-informed applications is inconsistent and unclear
- FLEX is being included contrary to the NRC guidance (e.g., use of current generic failure data)
- Several challenges exist requiring NRC and industry RISC engagement
- Numerous current activities to enable licensees to appropriately credit FLEX
- Draft report under development by NRR\RES on HRA for using FLEX to be made publicly available (1st Quarter 2019)
- Industry efforts:
- Industry is sharing FLEX operational experience with NRC staff
- To provide schedule for any industry guidance relating to HRA method development.
NRC Liaison Report Risk-Informed Activities 7
February 14, 2019
Tornado Missile Risk Evaluator
- Develop and demonstrate implementation of a risk-informed tornado missile protection evaluation model for licensees with non-conforming legacy design structures, systems, and components
- NEI 17-02, Revision 1, drafted for use by pilot plants
- Three pilot LARs have been submitted to NRC
- Staff issued safety evaluation for the first pilot application (ML18304A394)
- Post-pilot amendments could model pilot safety evaluations
- NRC reviews of the other pilots are in progress NRC Liaison Report Risk-Informed Activities 8
February 14, 2019
Realism in ROP
- Industry has expressed concerns about realism in the ROP and informed NRC that addressing their concerns relating to CCF is the highest priority
- Staff began review of the industry whitepaper on CCF (Revised whitepaper transmitted to NRC on January 12, 2018)
- NRC staff and management held public meeting to discuss (December 2018) NEIs CCF white paper
- NRC announced two-pronged approach during public meeting:
- NRC will release memo announcing a 1-year trial basis where licensees can submit info about defense strategies that might justify reducing CCF contribution to specific SDP findings
- Burden is on licensees to demonstrate why these defense strategies are not already baked into the existing alpha factors
- NRR and RES to explore viability of partial/causal alpha factor method NRC Liaison Report Risk-Informed Activities 9
February 14, 2019
PRA Acceptability NRC Regulatory Position (RP) (RG 1.200)
PRA Acceptability Consensus Standard Peer Review to demonstrate to demonstrate conformance with RP conformance with Standard All three elements must work together NRC Liaison Report Risk-Informed Activities 10 February 14, 2019
New Edition of the ASME/ANS PRA Standard (1 of 2)
- NRC considers it essential that the new edition of the Level 1 PRA standard be thoroughly reviewed
- Beyond consistency and technical correctness, the Level 1 PRA standard must work correctly across the various parts
- Key issues to be resolved in new edition of the Level 1 PRA standard:
- Definitions and implementation of risk-significance
- PRA Screening Criteria
- Table of hazards
- Criteria for peer review of a newly developed method
- NRC is participating in industry workshops to expeditiously resolve issues
- Public meetings to be held communicating status of issues NRC Liaison Report Risk-Informed Activities 11 February 14, 2019
New Edition of the ASME/ANS PRA Standard (2 of 2)
- Timeliness of the new edition of the Level 1 PRA standard and other PRA standards is becoming very important
- A stable version of the new edition of the Level 1 PRA standard is needed as soon as possible to support:
- numerous ongoing and increasing numbers of risk-informed activities for operating reactors
- the continued development and timely completion of multiple other standards.
- It is also critical to maintain the quality of the new edition of the Level 1 PRA standard.
- NRC issued a letter to the ASME and ANS Standards Boards (ML19031C904) describing the importance and priority of the PRA standards NRC Liaison Report Risk-Informed Activities 12 February 14, 2019
Non-LWR and Advanced LWR Activities (1 of 2)
- Continued progress on the ALWR and NLWR PRA standards is reliant on a stable version of new edition of the Level 1 PRA standard
- Proper vetting of the NLWR PRA standard is very important
- For example, a thorough comparison needs to be made between the NLWR PRA standard and the LWR standards
- The Nuclear Energy Innovation and Modernization Act recently became law on 1/14/2019 (Law No. 115-439)
- Section 103 specifically addresses advanced nuclear reactors
- Accelerates schedules for the expected use of the ALWR and NLWR PRA standards
- PRA standards need to be ready for potential applications
- Guidance on NLWR PRA peer review is needed, which could be developed by JCNRM or industry.
- The peer review team will need to understand the scope of the application and review the PRA accordingly NRC Liaison Report Risk-Informed Activities 13 February 14, 2019
Non-LWR and Advanced LWR Activities (2 of 2)
- NRC is developing an action plan for the review and endorsement of the NLWR PRA standard
- NRC endorsement of the NLWR PRA standard is expected to be provided in a new regulatory guide separate from RG 1.200
- Endorsement of the NLWR PRA standard is expected to be different and more complicated than in RG 1.200.
- Endorsement of the ALWR PRA standard is expected to be provided in RG 1.200, Revision 4 NRC Liaison Report Risk-Informed Activities 14 February 14, 2019
- RG 1.200, Revision 3 Draft guide tentatively scheduled for public review and comment late-2019 to early-2020 (dependent on schedule for the new edition)
Final RG with staff endorsement tentatively scheduled for late-2020/early-2021 Expected to endorse New Edition of Level 1 and the Level 2 PRA standards and NEI 17-07
- RG 1.200, Revision 4 Expected to endorse appendix to New Edition of the Level 1 PRA standard on advanced LWRs for design certification
- Interim NRC approval letters issued for:
NEI Appendix X to NEI 05-04, NEI 07-12, and NEI 12-13 Part 5 Code Case NEI 12-13 NRC Liaison Report Risk-Informed Activities 15 February 14, 2019
- NRC staff provided comments to NEI on NEI 17-07 in December 2018.
- NEI is piloting peer review of newly developed methods using NEI 17-07 in spring/summer 2019
- NRCs understanding is that NEI 17-07 will subsequently be updated based on lessons learned from the pilots and NRC comments
- NRC plans to issue interim approval letter for NEI 17-07 in the near-term and provide endorsement in RG 1.200, Revision 3 NRC Liaison Report Risk-Informed Activities 16 February 14, 2019
Acronyms ALWR advanced light-water reactor NEI Nuclear Energy Institute ANS American Nuclear Society NFPA National Fire Protection Association ASME American Society of Mechanical NLWR non-light-water reactor Engineers NOED Notice of Enforcement Discretion CC Capability Category NRC U.S. Nuclear Regulatory Commission CCF common-cause failure NRR Office of Nuclear Reactor Regulation CDF core damage frequency PRA probabilistic risk assessment CFR Code of Federal Regulations PWROG Pressurized-Water Reactor Owners Group CT completion time RES Office of Nuclear Regulatory Research EPRI Electric Power Research Institute RG Regulatory Guide FAQ Frequency Asked Question RISC Risk-Informed Steering Committee HRA Human Reliability Analysis RITSTF Risk-Informed TSTF JCNRM Joint Committee on Nuclear Risk ROP Reactor Oversite Process Management SDP Significance Determination Process LAR license amendment request SERP Significance and Enforcement Review LERF large early release frequency Panel LPSD low power and shutdown TS technical specification MOU memorandum of understanding TSTF Technical Specification Task Force NRC Liaison Report Risk-Informed Activities 17 February 14, 2019