ML24221A374
| ML24221A374 | |
| Person / Time | |
|---|---|
| Issue date: | 10/07/2024 |
| From: | David Williams NRC/NRR/DANU/UAL1 |
| To: | De Messieres C NRC/NRR/DANU/UTB2 |
| References | |
| RG-1.247 | |
| Download: ML24221A374 (1) | |
Text
October 7, 2024 MEMORANDUM TO:
Candace de Messieres, Chief Technical Branch 2 Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation FROM:
Donna Williams, Project Manager /RA/
Advanced Reactor Licensing Branch Division of Advanced Reactors and Non-Power Production and Utilization Facilities Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF THE JULY 30, 2024, PUBLIC MEETING BETWEEN THE U.S. NUCLEAR REGULATORY COMMISSION AND MULTIPLE STAKEHOLDERS TO DISCUSS COMMENTS ON THE TRIAL REGULATORY GUIDE 1.247, ACCEPTABILITY OF PROBABILISTIC RISK ASSESSMENT RESULTS FOR NON-LIGHT WATER REACTOR RISK-INFORMED ACTIVITIES Meeting Information:
Public Meeting Notice Agencywide Documents Access and Management System (ADAMS)
Accession No.: ML24190A044 Applicant Presentation Slides.: ML24218A183 and ML24218A185 NRC Staff Presentation Slides: ML24218A192 Meeting Attendees: See Enclosure 1 for list of meeting attendees.
Meeting Summary:
On July 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) held a public meeting with stakeholders. The announcement for this public meeting is available in ADAMS (ML24190A044). The purpose of this meeting was to communicate the NRC staff's (the staff) plan for finalizing Regulatory Guide (RG) 1.247 Acceptability of Probabilistic Risk Assessment Results for Advanced Non-Light Water Reactor Risk-Informed Activities for trial use, and to discuss comments from the Nuclear Energy Institute (NEI).
CONTACT: Donna Williams, NRR/DANU (301) 415-1322
Background:
RG 1.247, for trial use, describes one acceptable approach for determining whether a design-or plant-specific probabilistic risk assessment (PRA) used to support an application is sufficient to provide confidence in the results, such that the PRA can be used in regulatory decision-making for non-light water reactors (NLWRs). The trial use RG is intended to be consistent with the NRC's PRA Policy Statement (NRC, PRA Policy Statement, 60 FR 42622), and endorses, with staff exceptions, national consensus PRA standards provided by standards development organizations and nuclear industry organization guidance regarding the peer review process.
RG 1.247, for trial use, was issued on March 24, 2022, with a 60-day, post-promulgation public comment period (87 Federal Register (FR) 16770). The staff received comments from two organizations, Nuclear Energy Institute (NEI) and X-energy, during the comment period; a summary of these comments was included in the FR on October 17, 2022 (87 FR 62894).
The staff issued RG 1.247 as a trial use RG to give the staff the opportunity to revise the guidance based on insights from early implementation. Accordingly, in the FR notice announcing the trial RG issuance, the staff stated that the initial 60-day public comment period would be followed by a 2-year trial use period and at any time during the trial use period, a member of the public may submit suggestions on the NRC's public website at https://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.html. The staff also stated that the trial use period may be extended, as necessary, based on the experience obtained in the 2-year trial period. After the trial period, the staff indicated it would develop and issue a draft RG for public comment that will consider the stakeholder feedback and experience gained from the use of the trial RG.
The trial use period ended on May 23, 2024. The staff did not receive formal comments during the trial use period but was informed that NEI wanted to provide feedback consistent with its comments provided during the trial RG initial 60-day public comment period regarding the staffs qualification to HR-E4 in trial use RG 1.247. Specifically, in trial use RG 1.247, the staff took exceptions to the American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS) NLWR PRA standard regarding the treatment of errors of commission (EOCs) in a PRA.
In its comment, NEI disagreed with the inclusion of the qualification to HR-E4 indicating that it is not consistent with PRA state-of-practice and that broad consideration of EOCs for NLWRs is not consistent with EOC treatment for the current operating fleet.
During a public meeting in November 2022 (ML23025A411), the staff discussed its rationale for the exception regarding EOCs. The staff indicated that there is limited EOC-related operating experience for NLWRs and that the scope of the ASME/ANS NLWR PRA standard is broader than the scope of the ASME/ANS Level 1/LERF [large early release frequency] LWR [light-water reactor] PRA standard. Since EOCs may play a more important role in the NLWR PRA than in the LWR PRA, the staff highlighted the importance of EOC identification and consideration prior to elimination from consideration.
NRC staff presentation:
The staff communicated that, given the completion of the RG 1.247 trial use period, it intends to proceed with developing and finalizing RG 1.247. The trial use RG 1.247 will be withdrawn following publication of RG 1.247, Revision 0. The staff noted that RG finalization will occur over
an extended period to allow for continued consideration of near-term use of trial RG 1.247 in NLWR licensing activities. The staff communicated that it plans to issue draft RG 1.247, Revision 0 in March 2025 followed by a public comment period.
NEI remarks on RG schedule:
NEI noted that the industry has not completed a peer review following the guidance in trial use RG 1.247 and that certain comments submitted regarding trial RG 1.247 (i.e., comments related to EOC) were not adequately addressed. NEI noted that three NEI members are targeting peer reviews against the ASME/ANS NLWR PRA standard in 2025. NEI proposed a revised schedule for finalizing the RG that would delay publication of the draft RG to August 2025 so that it can be informed by two of these peer reviews, an NEI white paper on EOC (planned for issuance in fall 2024), and the near-term use of trial RG 1.247.
Staff response:
The staff asked for more information regarding the planned peer reviews and discussed how insights from the peer reviews may impact the positions in trial use RG 1.247. Following the public meeting, the staff considered NEIs proposal for extending the schedule for finalizing RG 1.247. The staff acknowledges that it may be constructive to consider insights from the first two peer reviews in the development of the draft RG. However, the staff needs additional information about the conduct of the peer reviews and the planned level of engagement with the staff during the peer review process to help inform whether such insights would substantively impact staff positions, which could in turn influence the current publication schedule for RG 1.247. As such, the staff plans to keep the current schedule of issuing the draft RG for comment in March 2025, but remains open to considering an extension to the schedule at a later date, if it determines that the RG will benefit from the peer review results as determined through additional discussions with the industry on the peer review schedules, process, and level of involvement by the staff (in public meetings or other format).
EOCs in Human Reliability Analysis (HRA) and PRA of Advanced Reactors Paul Amico, representing Jensen Hughes, provided a presentation titled Evaluating Aggravating Errors of Commission (EOC) in HRA/PRA of Advanced Reactors (ML24218A185).
He discussed the basis for excluding aggravating EOCs in the HRA and PRA for advanced reactors, potential approaches to limited consideration of EOCs for advanced reactors, and various technical HRA approaches on EOCs to support advanced reactor vendors. He noted that, based on the review of requirements, practices and methods related to modeling of aggravating EOCs, there are justifications for both excluding and including the aggravating EOCs.
Regarding limited operating experience for NLWRs, NEI noted its position that advanced reactor operators will have more time (hours or days) to correct an EOC so there would be limited instances in which a plant could not recover from an EOC. NEI stated that the industry has learned a lot from the operating fleet, and that advanced reactors have addressed potential EOCs in their designs.
NEI noted that for the operating fleet, consideration of EOCs is a best practice rather than a requirement and EOCs are less important for advanced reactors. NEI indicated that EOCs have been shown to be insignificant for the current generation of plants but acknowledged that it makes sense to do a limited qualitative screening to see where an EOC can occur.
The staff indicated that there is a lot of agreement between staff and industry on this topic, but highlighted there are significant variations in new designs and differences in how designers are addressing EOC-related lessons learned from the operating fleet.
NEI acknowledged the importance of performing research in the area of EOCs and emphasized that efforts should focus on recoverability of EOCs, not quantification of the EOC.
The staff shared background information on EOC-related insights from shutdown PRAs and on its endorsement of the NLWR PRA standard. The staff highlighted the importance for NLWR applicants to engage with the staff regarding design-specific impacts of EOCs. The staff also emphasized that RGs provide one acceptable approach to meet applicable regulations and that it will continue to consider stakeholder feedback in this area.
Next Steps:
NEI stated that they plan to submit a white paper on EOC in September 2024, after it has been shared with NEI members and approved by NEI management. NEI will submit the white paper as comments on the trial use RG. The staff clarified that comments will continue to be accepted on the trial use RG until a draft RG is issued.
The staff will consider the NEI white paper and determine if any changes to the qualification to HR-E4 in trial use RG 1.247 are warranted.
The staff will begin the process of finalizing the RG which may include additional public meetings to discuss stakeholder comments.
Enclosure:
As stated
ML24221A374 NRR-106 OFFICE NRR/DANU/UAL1:PM RES/DRA/PRB NRR/DANU/UTB2:BC NRR/DANU/UAL1:PM NAME DWilliams JLane CdeMesseires DWilliams DATE 8/12/2024 8/12/2024 10/05/2024 10/06/2024
Enclosure List of Attendees Public Meeting between the U.S. Nuclear Regulatory Commission and Multiple Stakeholders to Discuss Public Comments on the Trial Regulatory Guide 1.247 July 30, 2024 Name Organization Michelle Gonzales U.S. Nuclear Regulatory Commission (NRC)
Harriet Karagiannis NRC Hanh Phan NRC Anders Gilbertson NRC Christian Araguas NRC Marie Pohida NRC Erick Ball NRC James Chang NRC Latonia Enos-Sylla NRC Marty Stutzke NRC Nanette Valliere NRC Jesse Seymour NRC Virgel Furr NRC Niav Hughes Green NRC Jonathan DeJesus NRC Matthew Humberstone NRC Jonathan Evans NRC Gerardo Martinez-Guridi NRC Alan Kuritzky NRC Susan Cooper NRC Mehdi Reisi Fard NRC Kevin Coyne NRC Paul Amico Jensen Hughes Victoria Andersen NEI Jon Facemire NEI Ian Lynch NEI Raymond Burski ARC Clean Technology Edwin Lyman Jonathan Li GE Verona
Name Organization Bradley Dolan TVA Kyle Hope Burg, Rob EPM Cindy Williams NuScale Leigh Lloveras Breakthrough Institute Joy Jiang Ewa Muzikova Deann Raleigh Valerie Gorden