ML24137A229
| ML24137A229 | |
| Person / Time | |
|---|---|
| Issue date: | 05/13/2024 |
| From: | Lundy Pressley NRC/NRR/DRA/APOB |
| To: | Antonios Zoulis NRC/NRR/DRA/APOB |
| References | |
| Download: ML24137A229 (9) | |
Text
May 13, 2024 MEMORANDUM TO:
Antonios Zoulis, Chief PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation FROM:
Lundy Pressley, Reliability and Risk Analyst /RA/
PRA Oversight Branch Division of Risk Assessment Office of Nuclear Reactor Regulation
SUBJECT:
SUMMARY
OF APRIL 18, 2024, PROBABILISTIC RISK ASSESSMENT CONFIGURATION CONTROL SIGNIFICANCE DETERMINATION PROCESS PUBLIC MEETING WITH THE NUCLEAR ENERGY INSTITUTE AND OTHER INDUSTRY STAKEHOLDERS On April 18, 2024, the U.S. Nuclear Regulatory Commission (NRC) staff held an observation public meeting with the Nuclear Energy Institute (NEI) and industry, to continue the discussions between the NRC staff, industry stakeholders, and the public regarding enhancing the NRCs oversight of the licensees implementation of its Probabilistic Risk Assessment (PRA)
Configuration Control (PCC) process. This meeting offered an opportunity for the industry and public to gain familiarity and to provide feedback on the staffs PCC Significance Determination Process (SDP) proposal and was a follow-up meeting held at the request of Industry. Initial discussions on this topic began with a meeting held on March 21, 2024. Details related to the March 21st meeting may be found in the public meeting summary, available in ADAMS under the following Accession Number No.: (ML24109A046). Both the March 21st and April 18th meetings discussed SDP specifics as they relate to PCC issues. NRC staff and Industry presented approaches to how PCC issues would be processed through the screening process.
Most of the discussion focused on performance deficiencies, minor and more-than-minor and green and greater than green findings criteria.
The presentation for this public meeting is available (ADAMS Accession No. ML24108A174),
along with the NRC Draft PCC SDP Examples which were presented during the earlier March 21st meeting (ADAMS Accession No. ML24074A270). The presentation provided by NEI is included within the NRC presentation. The public meeting announcement is available (ADAMS Accession No. ML24109A023) and is associated in the Public Meeting Notification System as meeting number 20240467. A list of attendees (total 83) is included in Enclosure 1. The details of the meeting and discussion points are contained in Enclosure 2.
CONTACT: Lundy Pressley, NRR/DRA 404-997-4621
As of the date of this summary, the Public Meeting Feedback System had not received any feedback. No regulatory decisions or commitments were made at the meeting.
Enclosures:
- 1. List of Attendees
- 2. Meeting Details
- by e-mail OFFICE NRR/DRA/APOB NRR/DRA/APOB: BC NAME LPressley AZoulis DATE 4/10/2024 4/10/2024
LIST OF ATTENDEES Total number of attendees - 83 MARCH 21, 2024, PROBABILISTIC RISK ASSESSMENT CONFIGURATION CONTROL SIGNIFICANCE DETERMINATION PROCESS PUBLIC MEETING WITH NUCLEAR ENERGY INSTITUTE AND OTHER INDUSTRY STAKEHOLDERS Lundy Pressley NRC Antonios Zoulis NRC Doug Bollock NRC Pat Finney NRC Alex Garmoe NRC John Hanna NRC John Hughey NRC Meena Khanna NRC Philip McKenna NRC Qin Pan NRC Jeff Rady NRC Reinaldo Rodriguez NRC Andy Rosebrook NRC Gabe Taylor NRC Matthew Degonish AMEREN Justin Hiller AMEREN Isaac Mulhern AMEREN Michelle Carr Arizona Public Service (APS)
Michael Cymbor APS Mark Hulet APS Enrique Meléndez Consejo de Seguridad Nuclear (Spain)
Xavier Haro CONSTELLATION Fred Hazboun CONSTELLATION William Jameson CONSTELLATION Roy Linthicum CONSTELLATION Suzanne Loyd CONSTELLATION Jeff Stone CONSTELLATION Philip Tarpinian CONSTELLATION Jana Bergman CURTIS WRIGHT Robin Ritzman CURTIS WRIGHT Mary Miller DOMINION ENERGY Robert Rishel DUKE-ENERGY Heather Szews DUKE-ENERGY Byron Croker ENTERGY Wes Johnson ENTERGY Paul Sicard ENTERGY Rob Burg EPM Mark Schairer EPM Fernando Ferrante Electric Power Research Institute (EPRI)
John Richards EPRI David Alford EVERGY Lu Huang EVERGY David Vu EVERGY Luke Karten FPL Jadie Palenzuela FPL Keith Vincent FPL Brad Tyers GENERAL ELECTRIC Frank Hope JENSENHUGHES Edward Parsley JENSENHUGHES Andy Ratchford JENSENHUGHES Charles Standridge JENSENHUGHES Hunter Young JENSENHUGHES Victoria Anderson Nuclear Energy Institute Thomas Basso NEI Tony Brown NEI Gary DeMoss Public Service Energy Group (PSEG)
Cheryl Ann Gayheart SOUTHERN Vish Patel SOUTHERN Taeyong Sung SOUTHERN Russell Jones STPEGS Kristin Kaspar STPEGS Eric Browne Tennessee Valley Authority (TVA)
Monica Chlastosz TVA Bradley Dolan TVA Hongbing Jiang TVA Daniel Kearnaghan TVA Gerry Kindred TVA Mark Nicholson TVA Walter Boatwright WESTINGHOUSE Sinnathurai Gajanetharan XCEL ENERGY Adam Stein XCEL ENERGY Phil Couture Unaffiliated Jeff Bradley Unaffiliated Edwin Lyman Unaffiliated Paul Sicard Unaffiliated 6 unidentified callers Unaffiliated
MEETING DETAILS APRIL 18, 2024, PROBABILISTIC RISK ASSESSMENT CONFIGURATION CONTROL SIGNIFICANCE DETERMINATION PROCESS PUBLIC MEETING WITH THE NUCLEAR ENERGY INSTITUTE AND OTHER INDUSTRY STAKEHOLDERS PURPOSE To continue discussions between the U.S. Nuclear Regulatory Commission (NRC) staff, industry stakeholders and the public regarding enhancing the NRCs oversight of the licensees implementation of its Probabilistic Risk Assessment Configuration Control (PCC) process.
Specifically, the staff discussed proposals related to the Significance Determination Process (SDP) with respect to PCC issues. This meeting offered a second opportunity for the industry and public to provide feedback on the effort and on the staffs recommendation to enhance the oversight efforts associated with PCC.
BACKGROUND The objective is to develop a balanced approach for PCC oversight, closing an existing oversight gap in the reactor oversight process (ROP); and to develop the necessary guidance training and qualifications to support inspections in this area.
The current near-term oversight recommendation for PCC includes the use of an operating experience smart sample (OpESS) to be used as an additional tool by inspectors as part of ROP baseline inspection preparation. The information and trends identified from OpESS inspections will provide insight into the long-term oversight recommendations. The OpESS was issued and is publicly available (ADAMS Accession No. ML23255A006).
MEETING DETAILS Mr. Lundy Pressley of the NRC opened the workshop with a presentation (ADAMS Accession No. ML24108A174), which included information on PCC key messages, OpESS background and how the OpESS would be implemented, along with key points of the SDP proposal. NRC staff presented background information on the NRCs existing SDP process and how it would be applied for PCC and the OpESS. Details regarding cross regional panels, internal reviews, and controls for SDPs, including timelines and guidance from the NRC Enforcement policy concerning dispositioning multiple examples of findings were also discussed.
NRC staff then fielded questions from stakeholders related to the SDP proposal.
Industry asked how PCC findings would be quantified. NRC staff stated that Inspection Manual Chapter (IMC) 0609, App. K would be used as guidance, specifically using from App. K the difference or delta between the actual risk and the risk error.
Industry expressed concerns and asked about the technical basis for IMC 0609, App. K, which is IMC 0308, Att. 3 and how it will be revised. NRC staff replied that both IMCs will likely be revised in the future, as needed, based upon results from the OpESS.
Industry asked what model would be used for the quantification process. NRC staff replied the most likely a nominal model would be utilized for long term exposure times, however for risk informed completion time (RICT) scenarios a zero-maintenance model would possibly be applied. However, NRC staff stated that the application would generally be issue specific and that modeling and exposure times would be consistent with those utilized within IMC 0609, App. K.
Industry asked if there is a possibility to use IMC 0609 App. M, and NRC replied that staff do not intend to utilize App. M for this application.
Industry asked a question on best available information and how to resolve differences between licensee and NRC quantification results. NRC staff responded that the intent is to use the licensees results as the primary source and that NRC results would be used if there is uncertainty in modeling or to perform general independent assessments.
Industry asked about what potentially significant means regarding PCC. NRC staff responded that the term significant is not an NRC defined term, however NRC staff did refer to guidance contained within IMC 0612, specifically App. B to aid inspectors on an interpretation. Additionally, NRC staff added that inspectors should focus on important or significant issues by sample selection.
Industry expressed concern with the time involved to make the PRA model changes and that SDP has its own timeline. NRC staff responded that the NRC is sensitive to the time required to make in-process changes and will take that into account. Generally, if changes and model updates are being tracked within the licensees processes and managed with reasonable justification then that is most likely sufficient.
Industry asked how the SDP process would be approached if licensees were implementing multiple risk-informed programs (RIPs). NRC staff responded that the process would focus on the specific error and then determine the most applicable RIP that is affected or has the most impact and apply the focus there. This is consistent with NRC Enforcement Manual (ADAMS Accession No. ML23360A760) guidance contained in Part 1, Sections 1.3.4 and 1.3.5, related to documenting multiple examples of a violation.
The meeting then transitioned to a presentation from the Nuclear Energy Institute (NEI). The NEI presentation is contained with the NRC presentation and begins on slide 21, labeled Industry Presentation. The NEI presentation ends on slide 28.
The main points from the Industry/NEI presentation were noted as follows:
Key criteria for determining findings and violations and minor, more-than-minor.
Inspections should be examining what has happened, not what could have happened.
Assessments are against actual impacts on licensing applications (NFPA 805, 50.69, SFCP, RICT).
Need to ensure NRC and industry resources will not expend significant effort on issues that have little to no safety significance.
Performance deficiencies (PD) should have only one finding.
Additionally, NEI shared thoughts on what would constitute a minor violation, more-than-minor violation and a general flowchart on this topic was included in the presentation.
NRC staff expressed disagreements with some interpretations of NRC processes on the NEI flowchart, specifically with how some issues of concerns would not be considered as PDs.
Additionally, NRC staff expressed disagreement with the thresholds between minor and more-than-minor. NEI and NRC staff also debated the engineering calculation approach to screening issues as more-than-minor, and how a loss of margin is essentially considered an increased risk to the public. This approach is an existing method NRC uses to interpret reasonable doubt.
Industry expressed concern with NRCs interpretation of timeliness regarding reasonable doubt.
NRC staff responded that the timeliness approach was a means of controlling effort and expense on dispositioning issues between industry and the NRC staff. This concluded discussion on NEIs presentation.
NRC staff then offered to opportunity to discuss previously presented NRC draft SDP examples.
The draft examples are publicly available (ADAMS Accession No. ML24074A270) and are also contained within the NRC presentation beginning on slide 29.
NEI provided feedback on Example 1 and recommended that the description be rewritten to some form of data not updated in accordance with licensee procedures. NRC staff responded by referencing document NEI 06-09A, Risk-Informed Technical Specification Initiative 4b, Risk-Managed Technical Specifications Guidelines, (ADAMS Accession No. ML71200238), which was endorsed by the NRC. Industry and NEI agreed that while the requirement is to perform maintenance on the PRA, that may not necessarily include updating data during every two refueling outages.
Industry expressed concern with quantification of an issue if it was determined that the PD was more-than-minor and expressly stated that they were concerned about greater than green findings. NRC staff responded that staff are currently speculating that most issues would most likely not be greater than green, however at this point it could not be ruled out.
Therefore, NRC would keep the current SDP process in place and perhaps later determine that all PCC issues would screen to green, however, more data is needed on the types of issues that are encountered before drawing any further conclusions. NRC staff also expressed that RICT issues are likely the exception, to considering all issues green or less, given the risk and very short timelines encountered for the risk exposure.
Industry questioned the reference to mitigation system performance indicators in Example 1 and stated that the PRA model that is approved at the end of the quarter is what is used for the next quarter, and that licensees cannot go back and change that. NRC staff responded that the reference would be reconsidered and that it was likely included as a point of reference for possible failure updates.
Industry questioned referencing any violations back to the PRA Standard given that the Standard is vague on PRA model maintenance and recommended referring instead for licensee maintenance and update process procedures. NRC replied that the PRA Standard is the regulatory requirement and that it is generally understood that licensee procedures should meet the minimum requirements contained within the PRA Standard.
Industry expressed concern with Example 4 and use of the term error, adding that every PRA model contains errors and that these errors being subject to a violation does not make sense, especially given that most of these errors would likely have no impact on safety. NRC staff responded that a better term could be a PD as opposed to an error.
NRC staff and NEI/Industry agreed to conclude the meeting early given there were no additional questions. This concluded the business section of the meeting.
NRC staff opened the meeting to comments from any members of the public and there were no comments. Ms. Meena Khanna, Deputy Director of the Division of Risk Assessment, provided the closing remarks, and the meeting was concluded.