ML18331A370
| ML18331A370 | |
| Person / Time | |
|---|---|
| Site: | Nuclear Energy Institute |
| Issue date: | 12/03/2018 |
| From: | Blake Purnell Plant Licensing Branch III |
| To: | David Wrona Plant Licensing Branch III |
| Purnell B, 415-1380 | |
| References | |
| Download: ML18331A370 (6) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 3, 2018 MEMORANDUM TO: David J. Wrona, Chief Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
( ., '
FROM: Blake Purnell, Project Manager J Plant Licensing Branch Ill Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF NOVEMBER 14, 2018, MEETING WITH THE NUCLEAR ENERGY INSTITUTE AND OTHER INDUSTRY REPRESENTATIVES REGARDING USE OF NEW PROBABILISTIC RISK ASSESSMENT METHODS On November 14, 2018, a Category 2 public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) staff and industry representatives for power reactors. The purpose of the meeting was to discuss proposals to use newly-developed methods in probabilistic risk assessment (PRA) models following implementation of a risk-informed process.
The proposals are based on the use of the peer-review process, complemented by an enhanced reactor oversight process (ROP) for risk-informed initiatives. The meeting notice and agenda, dated October 30, 2018, are available in the Agencywide Documents Access and Management System (ADAMS) at Accession No. ML18303A392. Presentations were made by the NRC staff, the Nuclear Energy Institute (NEI), and the Pressurized Water Reactor Owners Group (PWROG). Other industry representatives participated in the discussions. A list of attendees is enclosed.
Use of New PRA Methods The NEI representative presented slides (ADAMS Accession No. ML18312A352) on the
- treatment of PRA methods for use by licensees that are adopting Technical Specifications Task Force (TSTF) traveler TSTF-505, "Provide Risk-Informed Extended Completion Times -
RITSTF Initiative 4b" (ADAMS Package Accession No. ML17290A003). NEI proposed milestones that, in their view, need to be met to support TSTF-505 implementation. The NRC staff acknowledged NEl's need for expediency on the subject, and committed to propose alternate schedules that considers the relative priority of this task to numerous other risk-informed priorities that involve the NRC's risk-assessment staff.
As a follow-up to a commitment made during the public meeting on September 6, 2018, NEI provided a survey of the results regarding planned use of newly-developed methods. NEI reported that the scope is small, and primary consists of methods that will emanate from Electric Power Research Institute fire research to be conducted from 2018-2020 and one or two other methods. This estimate depends upon the final definition of newly-developed methods.
NEI also noted that there are two utilities interested in piloting the process for reviewing newly-developed methods, but no specific plant has been selected. The NRC staff noted that the pilot would need to provide the staff confidence in the peer-review process for the staff to consider the pilot successful.
The NRC staff gave presentations on the use of newly-developed methods in PRA models and a status update on the planned enhancement to the ROP associated with risk-informed initiatives (ADAMS Accession No. ML18317A050 and ML18331A390, respectively). The staff discussed the desired endpoints and challenges on the path forward. Staff re-emphasized that peer-reviewers do not approve newly-developed methods on behalf of the staff. The staff identified five tasks that must be completed to achieve the desired end point:
(1) Update NRC Regulatory Guide (RG) 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities" (ADAMS Accession No. ML090410014);
(2) Enhance the ROP to support risk-informed initiatives; (3) Endorse NEI 17-07, "Performance of PRA Peer Review Using the ASME/ANS [American Society of Mechanical Engineers/American Nuclear Society] PRA Standard";
(4) Endorse the near-term products of the PWROG work to develop definitions and review criteria for newly-developed methods; and (5) Develop or enhance NRC processes to accommodate NEl's proposal.
The NRC staff stated that its goal is to complete the last three items during fiscal year 2019.
Feedback on NEI Guidance On November 9, 2018 (ADAMS Accession No. ML18313A246), the NRC provided detailed comments to NEI on the draft NEI 17-07, Revision A (ADAMS Accession No. ML17341A548) by e-mail. The NRC presentation (ADAMS Accession No. ML18317A050) at the meeting focused on high-level feedback on the draft NEI 17-07. The staff noted that it compared the NEI 17-07 guidance to previous guidance documents. The staff encouraged the consolidation of peer-review guidance, since there are currently multiple guidance documents on the topic. The NRC staff and NEI agreed to set up public teleconferences in the near term to go over the comments in detail.
The major NRC staff comments on NEI 17-07 included the following:
- Every supporting requirement has to be peer reviewed for a full-scope review, but not for a focused scope review. However, NEI 17-07 infers that the peer review does not need to consider every supporting requirement. The industry noted that some peer reviews can identify supporting requirements that are not applicable.
- NEI 17-07 does not address internal flooding.
- NEI 17-07 states that consensus requires all to agree with the final assignment. NEI stated it will revise the guidance to address this issue.
- The findings and observations of the peer review should identify new methods, similar to the identification of best practices. The industry representatives stated that a new method should not be considered as a finding or observation, and were concerned about how this item would be closed. The staff noted that best practices and other items do not require closure.
- There should be limitations on when a licensee can request a review to Capability Category I (CC I). RG 1.200 states that CC II is the acceptable target. The industry noted that new reactors may only be able to review to CC I. The staff stated that review to CC II can improve efficiency, but the staff does not want to create unintended consequences for new reactors.
The NRC staff stated that it plans to eventually endorse NEI 17-07 in Revision 3 to RG 1.200.
The staff discussed the status of the revision to RG 1.200, and noted that it is dependent on the completion of the new edition to ASME/ANS PRA standard. The staff is considering interim approval of NEI 17-07. The staff noted that the revision to RG 1.200 would apply to new peer reviews, but that licensees would not be expected to redo peer reviews done under previous revisions to RG 1.200.
Working Meeting on PRA Upgrade Definition The PWROG representative presented slides (ADAMS Accession No. ML18317A054) on a November working meeting to revise the PRA upgrade definition in the ASME/ANS PRA standard. The representative described proposed definitions for PRA upgrade, PRA maintenance, PRA method, PRA, and newly developed methods. The NRC staff stated it would likely take exception to clarify that the NRC would consider a method to be newly developed if it has not been reviewed by the NRC. The staff noted that the standard could not include such NRG-specific wording.
The PWROG representative also discussed proposed guidance for determining when a peer review is required. The industry proposed to maintain a list of examples, rather than including them in the ASME/ANS PRA standard. The industry stated that it would provide the NRC access to the list, but the list would not be public.
The industry representatives also stated that as the risk profile for the plant has changed, the 95 percent threshold in the PRA standard for summed contribution of sequences is resulting in more items being flagged as risk-significant. The industry is considering looking into alternatives. The PWROG representative also discussed external hazards screening.
The PWROG stated it was looking to develop a tiered peer-review process. The concept would be to reduce the review requirements for upgrades that have a small scope or where the licensee has previously demonstrated it can correctly apply the method.
The industry stated that the definitions related to PRA upgrade was the only item discussed during the PWROG presentation that is needed for TSTF-505. The other items discussed would be included in the ASME/ANS PRA standard and can wait for the revision to RG 1.200.
Conclusion The NRC staff concluded with the following items:
- The NRC plan to endorse NEI 17-07 needs to be formalized, with a goal of completing within about 1 year.
- The NRC needs to develop a plan for issuing a letter (within about 1 year) that documents the issues important to addressing new methods that will be included in the revision to RG 1.200.
- The finalization of the plan to enhance the ROP to support risk-informed initiatives is a longer term item.
- The NRC and industry need to align on the content of reports to the NRC on newly-developed PRA methods. This is needed to support the NRC staff development of the oversight processes for newly-developed methods.
- The inspection process needs to be considered as the industry transitions from licensing to oversight of risk-informed initiatives.
Public meeting feedback forms were not received. Please direct any inquiries to me at 301-415-1380, or Blake.Purnell@nrc.gov.
Project No. 0689
Enclosure:
List of Attendees cc: Listserv
LIST OF ATTENDEES NOVEMBER 14, 2018, MEETING WITH INDUSTRY Name Affiliation Blake Purnell NRC Mary Drouin NRC Sunil Weerakkody NRC Antonios Zoulis NRC Stephen Dinsmore NRC JS Hyslop NRC Mike Markley NRC Mike Franovich NRC Mehdi Reisi Fard NRC Candace de Messieres NRC Dale Yielding NRC De Wesley Wu NRC Jonathan Evans NRC Gregory Suber NRC Mike Cheok NRC Mihaela Biro NRC Mark Thaggard NRC Donald Helton NRC John Schrage Enterav Jana Bergman Curits-Wright Roy Lithicum PWROG Victoria Anderson NEI Greg Krueger NEI Jeff Stone Exelon Owen Scott Southern Nuclear Co.
Faramarz Pournia Southern Nuclear Co.
E. E. Luenqas Luminant Barry Sloane Jensen Hughes Travis Weber Engineerinq PlanninQ and Manaqement, Inc. (EPM)
James Liming ABS Consulting Bruce Morgen EPM Jamie McCrory Duke Energy Fatma Yilmaz South Texas Project Nuclear Operating Company Bruce Huhmann Ameren Stanley Levinson Framatome Deepak Rao Enterav Thomas Morgan ENERCON Services, Inc.
Matt Denman Sandia Jeff LeClair Xcel Enerav Jim Lechner Jensen Hughes Jayne Ritter Xcel Enerav Enclosure
ML18331A370 OFFICE NRR/DORL/LPL3/PM NRR/DORL/LPL3/LA NRR/DORL/LPL3/BC NRR/DORL/LPL3/PM NAME BPurnell SRohrer DWrona BPurnell DATE 11 /28/18 11/28/18 12/3/18 12/3/18