ML25014A311
| ML25014A311 | |
| Person / Time | |
|---|---|
| Site: | Electric Power Research Institute |
| Issue date: | 02/03/2025 |
| From: | Lois James Licensing Processes Branch |
| To: | Kucuk A Electric Power Research Institute |
| Shared Package | |
| ML25014A287 | List: |
| References | |
| EPRI TR 3002028674, EPRI TR 3002028675, EPID L-2024-TOP-0015 pre-fee, EPID L-2024-NTR-0003 post-fee | |
| Download: ML25014A311 (1) | |
Text
OFFICIAL USE ONLY PROPRIETARY INFORMATION OFFICIAL USE ONLY PROPRIETARY INFORMATION REGULATORY AUDIT PLAN BY THE OFFICE OF NUCLEAR REACTOR REGULATION IN SUPPORT OF THE REVIEW TECHNICAL REPORT 3002028674/5, LOCA ANALYSIS OF FUEL FRAGMENTATION, RELOCATION, AND DISPERSAL FOR WESTINGHOUSE 2-LOOP, 3-LOOP, AND 4-LOOP PLANTS REVISION 0 ELECTRIC POWER RESEARCH DOCKET NO. 99902021
1.0 BACKGROUND
By letter dated April 26, 2024 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML24121A203), Electric Power Research Institute (EPRI) submitted (1) EPRI Report 3002028673, Loss-of-Coolant-Accident-Induced Fuel Fragmentation, Relocation, and Dispersal with Leak-Before-Break Credit - Alternative Licensing Strategy
[ALS], (2) EPRI Report 3002028675 (NP)/3002028674 (P), LOCA[Loss of Coolant Accident]
Analysis of Fuel Fragmentation, Relocation, and Dispersal [FFRD] for Westinghouse 2-Loop, 3-Loop and 4-Loop Plants - Proprietary, Evaluation of Cladding Rupture in High Burnup Fuel Rods Susceptible to Fine Fragmentation (collectively called ALS for LOCA Analysis of FFRD),
and (3) EPRI Report 3002023895, Materials Reliability Program: xLPR [Extremely Low Probability of Rupture] Estimation of PWR Loss-of-Coolant Accident Frequencies (MRP-480) to the U.S. Nuclear Regulatory Commission (NRC) for review and approval.
By email dated June 25, 2024 (ADAMS Accession No. ML24170A812), the NRC accepted the EPRI topical reports (TRs) for review and approval. The NRC acceptance package includes completion forms and schedules for three TRs, and the withholding determination for the proprietary TR.
The NRC staff has performed an initial review of EPRI Report 3002028675 (NP)/
3002028674 (P) and determined that a regulatory audit of the items in the Information Requests and Audit Topics sections of this audit plan would facilitate the timely completion of our review.
The NRC staff is continuing to review other aspects of the topical report and may identify the need to audit additional subjects by separate correspondence or during audit discussions. The regulatory audit will be conducted in accordance with the Office of Nuclear Regulatory Reactor Office Instruction (OI) LIC-111, Regulatory Audits, Revision 1, dated October 2019 (ADAMS Accession No. ML19226A274).
OFFICIAL USE ONLY PROPRIETARY INFORMATION OFFICIAL USE ONLY PROPRIETARY INFORMATION A regulatory audit is a planned license or regulation-related activity that includes the examination and evaluation of primarily non-docketed information. The audit is conducted with the intent to gain understanding, to verify information, and to identify information that will require docketing to support the basis of a licensing or regulatory decision. Performing a regulatory audit is expected to assist the NRC staff in efficiently conducting its review and gaining insights to the vendors processes and procedures. Information that the NRC staff relies upon to make the safety determination must be submitted on the docket.
2.0 REGULATORY AUDIT BASES NRC current regulations at Title 10 of the Code of Federal Regulation (10 CFR) Section 50.46, Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors, limits peak cladding temperature and maximum cladding oxidation to satisfy General Design Criterion (GDC) No. 35 of Appendix A to Part 50, Emergency core cooling, which requires, in part, that The system safety function shall be to transfer heat from the reactor core following any loss of reactor coolant at a rate such thatclad metal-water reaction is limited to negligible amounts.
In other words, FFRD can challenge core coolability, so the simplest approach to demonstrate that GDC 35 is met is to demonstrate that no fuel dispersal occurs..
Nuclear power plant (NPP) licensees have informed the NRC that NPPS are considering the use of higher burnup fuel designs to meet operational objectives. However, FFRD is a technical challenge to the use of higher burnup fuel designs. EPRI has developed an alternative licensing approach for utilization of higher burnup fuel rods in PWRs which has been submitted to the NRC for review and approval (ADAMS Package Accession No. ML24121A203).
EPRI Report 3002028675 (NP)/3002028674 (P) presents the results of cladding rupture calculations for small-break and intermediate-break LOCA, which indicate that cladding rupture would likely not occur in high burnup fuel rods susceptible to fine fragmentation for specific Westinghouse fuel designs utilized in 2-Loop, 3-Loop, and 4-Loop Westinghouse PWRs. If cladding rupture would not occur, finely fragmented fuel would not disperse from the high burnup fuel rods into the reactor coolant during a LOCA.
3.0 REGULATORY AUDIT SCOPE The NRC staff will conduct a virtual audit which will include technical discussion pertaining to potential request for additional information questions as well as comprehension questions on the TR itself. The purpose of this audit is to gain a more detailed understanding of the information supporting EPRIs proposed topical report methodology.
The areas of focus for the regulatory audit are the information contained in the submitted topical report, the enclosed audit information needs, and all associated and relevant supporting documentation (e.g., methodology, process information, calculations, etc.) identified below.
OFFICIAL USE ONLY PROPRIETARY INFORMATION OFFICIAL USE ONLY PROPRIETARY INFORMATION
- 6. Discussion related to the atmospheric dump valve, safety relief valve, and Mass Flow and Energy Release Treatment described in Section 3.1.7 with particular interest in the impact on the type of steam generator.
- 7. A discussion related to the parameters in Section 3.1.8 and any potential parameters that should be included in the composite design envelope.
- 8. The phenomenon labeled, Non-Condensable Effects, as it related to the cold leg / safety injection section in Table 2-1 of WCAP-16696 indicates an ((
)). According to the proposed methodology this phenomenon should be accounted for in the design envelope but does not appear be discussed in the TR.
- 9. Discussion related to fuel rod average burnup as described in Section 3.3.
- 10. Discussion related to the PCTs presented in Figures 3.5-1 through 3.5-3 and how they compare to the PCTs calculated in Sections 4.0. The staff is particularly interested in the following:
- a. Why do the values in the Tables in Section 3.5 not agree with the values estimated from the Figures in Section 4.0?
- b. Some of the PCTs in Tables 3.5-1 through 3.5-3 are in excess of the expected cladding rupture temperature.
- 11. Discussion related to the concurrent review of WCAP-18850 and the impacts to the review of EPRI Report 3002028674/5.
- 12. Discussion related to the implementation of EPRI Report 3002028674/5.
- 13. Discussion related to the treatment of parameters described in Section 3.0 of the TR.
5.0 TEAM AND R EVIEW ASSIGNMENTS The audit team will consist of the following NRC staff:
NAME ASSIGNMENT DIVISION BRANCH Lois James Senior Project Manager Division of Operating Reactor Licensing (DORL)
Licensing Projects Branch (LPLB)
James Delosreyes Project Manager DORL LLPB Brandon Wise Reactor Systems Engineer Division of Safety Systems (DSS)
Nuclear Methods and Fuel Analysis Branch (SFNB)
John Lehning Senior Nuclear Engineer DSS SFNB Seung Min Materials Engineer Division of New and Renewed Licenses (DNRL)
Piping and Head Penetrations Branch (NPHP)
OFFICIAL USE ONLY PROPRIETARY INFORMATION OFFICIAL USE ONLY PROPRIETARY INFORMATION David Rudland Senior Level Advisor for Nuclear Power Plant Materials DNRL Matthew Leech Reliability and Risk Analyst Division of Risk Assessment (DRA)
PRA Licensing Branch A (APLA) 6.0 LOGISTICS The audit will be conducted from November 26, 2024, to January 31, 2025, through an online portal (also known as electronic portal, ePortal, or electronic reading room) established by EPRI.
The audit team will conduct a TEAMS-based entrance meeting with the vendor on November 26, 2024, for the purposes of introducing the team, discussing the scope of the audit, and describing the information to be made available on the portal. Through the audit period between November 26, 2024, to January 31, 2025, the NRC staff will hold breakout sessions with representatives of EPRI to answer audit team questions and to have technical discussions.
An exit meeting/call will be held at the conclusion of the audit on January 31, 2025.
The NRC staff does not foresee the need for an onsite visit or in-person discussions between the NRC and vendor staff to discuss information to be provided on the portal at this time.
However, if the need for a such a meeting is identified in the future, the audit plan will be revised, and the schedule for the audit will be adjusted accordingly. The NRC project manager (PM) will coordinate any changes to the audit schedule and location with the vendor.
7.0 SPECIAL REQUESTS The audit team would like access to the documents listed in Section 4.0 above through an online portal that allows the audit team to access documents via the internet. The following conditions associated with the online portal must be maintained throughout the duration that the audit team has access to the online portal:
The online portal will be password-protected, and separate passwords will be assigned to the NRC staff who are participating in the audit.
The online portal will be sufficiently secure to prevent the NRC staff from printing, saving, downloading, or collecting any information on the online portal.
Conditions of use of the online portal will be displayed on the login screen and will require acknowledgement by each user.
Username and password information should be provided directly to the NRC staff. The NRC PM will provide to EPRI the names and contact information of the NRC staff who will be participating in the audit. All other communications should be coordinated through the NRC PM.
8.0 DELIVERABLES
OFFICIAL USE ONLY PROPRIETARY INFORMATION OFFICIAL USE ONLY PROPRIETARY INFORMATION An audit summary report will be prepared within 90 days of the completion of the audit. If the NRC staff identifies information during the audit that is needed to support its regulatory decision, the NRC staff will issue RAI(s) to the vendor.