ML25177B722
| ML25177B722 | |
| Person / Time | |
|---|---|
| Issue date: | 07/07/2025 |
| From: | Delosreyes J Licensing Processes Branch |
| To: | Jennivine Rankin Licensing Processes Branch |
| Shared Package | |
| ML25177B920 | List: |
| References | |
| Download: ML25177B722 (6) | |
Text
July 7, 2025 MEMORANDUM TO:
Jennivine K. Rankin, Acting Branch Chief Licensing Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
James Delosreyes, Project Manager /RA/
Licensing Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
MEETING
SUMMARY
OF THE MAY 20-21, 2025, U.S. NUCLEAR REGULATORY COMMISSIONS ASSESSING THE RADIOLOGICAL CONSEQUENCES AND RISK OF A 50.46 LOSS-OF-COOLANT ACCIDENT WORKSHOP On May 20-21, 2025, the U.S. Nuclear Regulatory Commission (NRC) staff held a public workshop with representatives of industry to discuss topics related to Fuel Fragmentation, Relocation, and Dispersal (FFRD) including a proposed white paper submittal from the Nuclear Energy Institute (NEI). The meeting was held in a hybrid format (i.e., attendance in-person, virtual, and teleconference) and conducted over two days. The meeting notice is available in the Agencywide Documents Access and Management System (ADAMS) under Accession No. ML25139A581. The presentation slides are available in ADAMS under Accession No. ML25139A489. The list of attendees for this meeting is enclosed with this memorandum.
The NRC staff began the public meeting with an introduction and explanation of logistical information. Jen Whitman, NRCs Director of the Division of Safety Systems, and Al Csontos, NEIs Director of Fuels, provided opening and closing remarks. The topics discussed during the meeting are summarized below.
No regulatory decisions were made during this meeting.
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Background===
This workshop is intended as the first in a series of workshops to discuss topics related to FFRD to take place over the next several months. Most, if not all, of these workshops will also serve as a venue to discuss draft submittals from industry for white papers related to the topics of discussion.
CONTACT:
James Delosreyes, NRR/DORL 301-415-4141 An Approach to Address Fuel Dispersal During a Loss-of-Coolant Accident (LOCA) Using Dose Consequences and Risk Insights The NRC staff presented updates on the technical basis development for a potential approach to evaluating dose of fuel dispersal and using risk insights to disposition other fuel dispersal consequences. The presentation began with a background on FFRD including perspectives on consequences, risk, and dose with relation to regulatory requirements. This included an overview of the approach of how guidance and other work could potentially be used to meet the regulations and how ongoing research may be leveraged. This was followed by a detailed discussion on the topics of technical basis development for recriticality and coolability. Future work by the NRC staff includes further calculations and modeling to support this development.
Risk Significance of LOCAs and Justification for a Risk-Informed Transition Break Size (TBS)
The industry representatives presented on their draft white paper submittal which could potentially be used to support alternative licensing pathways for future power uprate and high burnup fuel applications. Among their stated objectives was to provide for regulatory flexibility, stability and predictability in the near and long-term future. The presentation began with chronology of risk modeling and programs and the specific risk from LOCA events for various combinations of plant type and leak size. They asserted that the risk significance is generally quite low with some granularity among the different leak sizes. Similarly, the industry representatives stated that the risk consequences would not be limiting from a health perspective. Using this background, industry representatives described three potential licensing pathways to allow for a risk-informed approach to FFRD.
Discussion Following the presentations, an open discussion period was conducted with a focus on the NRC staff asking clarifying questions on the draft white paper and providing feedback. The discussion topics were grouped into five broad categories.
- 1. Balance of Risk and Deterministic Information The NRC staff asked how this approach would apply to new reactors lacking in operating experience. The industry representatives responded that the risk-informed TBS approach described in the white paper would be generically applicable to new reactors which are required to have probabilistic risk assessment programs per regulations. The licensee would have to demonstrate applicability during its design certification or other established processes.
- 2. Acceptance Criteria for Approach The NRC staff asked about the criteria for determining the Core Damage Frequency (CDF) threshold and if other risk metrics, such as Large Early Release Frequency (LERF) would be included. The industry representatives explained that this would be addressed in an upcoming workshop and discussed whether to combine the risk-informed TBS approach and CDF methodology into one or two white papers. The discussion highlighted the connection between different regulatory pathways and the need for a clear framework. Concerns were raised about the timelines and the need for a structured approach to address technical issues fairly. The NRC staff acknowledged the complexity of the regulatory framework and emphasized the importance of developing a solid technical basis before finalizing the regulatory implementation.
- 3. Implementation of Approach The NRC staff asked about the time frame needed for regulatory decisions to support industry plans. The industry representatives indicated that to support a 2029 startup date for high burn-up, high enrichment cores, regulatory decisions are needed by 2027 to allow time to develop and submit License Amendment Requests. The discussion emphasized the importance of regulatory efficiencies and the need for a clear path to meet strategic goals. Concerns were raised about the varying implementation times for different pathways and the necessity of vendor methodology approvals. The NRC staff acknowledged the tight timelines and the need for continued collaboration to ensure efficient processing of submittals.
- 4. Policy Implications The NRC staff raised concerns about the policy implications of establishing a CDF threshold for LOCAs and how it compares to other events. The industry representatives emphasized that LOCAs have lower risk significance due to robust design and are not advocating for changes to existing design criteria. The discussion highlighted the potential for a broader policy shift if the same logic is applied to other events, raising concerns about consistency and precedent. The industry representatives reiterated their focus on risk-informed decision-making to allocate resources effectively, while acknowledging the need for careful consideration of the broader implications.
- 5. Future White Paper and Discussion Plans The industry representatives outlined the progression and prioritization of upcoming workshops.
The next workshop will focus on coolability evaluations and reporting requirements, aiming to streamline the reporting requirements and align those requirements with current PRA standards.
The third workshop, likely to occur by the end of August 2025, will delve deeper into the topics discussed, including the risk-informed TBS concept and a graded approach for LOCAs. The fourth workshop, expected around September 2025, will address in-service inspections and materials degradation research.
Public Comments One member of the public made one comment during this meeting. The person expressed concern that industry has been attempting to dismiss the risk and consequences of FFRD without adequate support. The person stated that FFRD is a poorly understood phenomenon and diminishing its level of risk should not allow for accepting more risk elsewhere. The person then asked a question to the NRC staff regarding station blackouts contribution to CDF and whether FFRD will have any material impact on the progression of a station blackout accident and any technical basis.
The NRC staff responded that the FFRD phenomenon should not occur during a station blackout accident, which is expected to progress at system pressure, unless the reactor also suffered depressurization during the event to allow for the ballooning and bursting of the fuel cladding.
Enclosure:
List of Attendees
Enclosure LIST OF ATTENDEES U.S. Nuclear Regulatory Commission Assessing the Radiological Consequences and Risk of a 50.46 LOCA Workshop May 20-21, 2025 9:00 am - 12:00 pm U.S. Nuclear Regulatory Commission (NRC)
First Name Last Name Marissa Bailey Ronald Ballinger Philip Benavides Ankur Bhattacharya Andrew Bielen Christopher Brown Mike Call Alice Chung James Corson Vic Cusumano James Delosreyes Elijah Dickson David Dijamco Dan Frumkin David Garmon Kevin Heller Kevin Hsueh Joshua Kaizer Meena Khanna Michelle Kichline Daniel King Scott Krepel John Lehning Ekaterina Lenning Sean Meighan Joseph Messina Seung Min Steven Muller Jared Nadel John Parillo Jennie Rankin Patrick Raynaud Aida Rivera-Varona David Rudland Edward Stutzcage Robert Tregoning Chris Van Wert Shilp Vasavada Weidong Wang Sunil Weerakkody Jen Whitman Josh Whitman Non-NRC First Name Last Name Organization (if provided)
Don Algama Department of Energy Victoria Anderson Nuclear Energy Institute (NEI)
Kevin Barber Westinghouse Electric Company (Westinghouse)
Dwayne Blaylock Enercon Michael Boone Westinghouse Greg Broadbent Entergy Damon Bryson Duke Paul Clifford Framatome Price Alexander Collins Duke Aladar Csontos NEI Brad Dolan Tennessee Valley Authority Dennis Earp Jr.
Duke Jerrod Ewing Westinghouse Ferando Ferrante Electric Power Research Institute (EPRI)
Keith Gregory Fox Idaho National Laboratory Lisa Gerken Framatome Mark Conrad Handrick Duke Zeses Karoutas Westinghouse Tom Kindred Southern Nuclear Company (SNC)
Jeffrey Kobelak Westinghouse Samuel Lafountain SNC Guangjun Li General Electric (GE)
Christopher Logan American Electric Power (AEP)
Edwin Lyman Union of Concerned Scientists Alex Markivich Dominion Tara Elizabeth Matheny Duke Brian Mount Dominion Kurshad Muftuoglu EPRI Jane-Erika Murphy Constellation Matthew Nudi EPRI Stephen O'Hearn Dominion Frances Pimentel NEI Steven Pope Information Systems Laboratories Ian Porter GE Baris Sarikaya Constellation Raymond Schneider Westinghouse Fred Smith EPRI Charles Stroupe Duke Dallas Swihart Duke Yoshinori Takechi Nuclear Regulation Authority Japan Milan Tesinsky Westinghouse Daniel Vincent AEP Lewis Wells Constellation Gordo Wissinger Framatome Zefeng Yu Westinghouse
Package: ML25177B920 Meeting Summary: ML25177B722 Meeting Notice: ML25139A581 Meeting Slides: ML25139A489 OFFICE NRR/DORL/LLPB/PM NRR/DORL/LLPB/LA NRR/DORL/LLPB/BC NRR/DORL/LLPB/PM NAME JDelosreyes DHarrison JRankin JDelosreyes DATE 6/27/2025 7/1/2025 7/7/2025 7/7/2025