ML24278A134
| ML24278A134 | |
| Person / Time | |
|---|---|
| Site: | Westinghouse |
| Issue date: | 10/17/2024 |
| From: | Gerond George Licensing Processes Branch |
| To: | Zozula C Westinghouse |
| References | |
| EPID L-2023-TOP-0054 | |
| Download: ML24278A134 (5) | |
Text
October 17, 2024 Camille Zozula Manager, Infrastructure & Facilities Licensing Westinghouse Electric Company 1000 Westinghouse Drive, Building 1 Cranberry Township PA 16066
SUBJECT:
REPORT FOR THE U.S. NUCLEAR REGULATORY COMMISSION CLOSED REGULATORY AUDIT CONDUCTED ON JUNE 10-14, 2024, FOR THE REVIEW OF WESTINGHOUSE ELECTRIC COMPANY TOPICAL REPORT WCAP-18904-P/NP, REVISION 0, CRITICAL POWER EXPERIMENTS AND D6 CPR CORRELATION FOR TRITON11 FUEL (EPID L-2023-TOP-0054)
Dear Camille Zozula:
By the letter dated November 3, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23307A183), Westinghouse Electric Company (Westinghouse) submitted Topical Report (TR) WCAP-18904-P/NP, Revision 0, Critical Power Experiments and D6 CPR Correlation for TRITON11 Fuel, to the U.S. Nuclear Regulatory Commission (NRC) for review and approval.
The NRC staff conducted a hybrid (in-person and virtual) closed regulatory audit on June 10 through 14, 2024, to discuss major topics of the TR review. The non-proprietary audit report is enclosed. Nathaniel Mackereth, Westinghouse, confirmed via email dated October 15, 2024, that the enclosed audit report does not contain any proprietary information.
If you have any questions, please contact Ekaterina Lenning via phone at 301-415-3151 or via email at Ekaterina.Lenning@nrc.gov.
Sincerely,
/RA/
Gerond A. George, Chief Licensing Projects Branch Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 99902038
Enclosure:
Audit Report
Enclosure U. S. NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION AUDIT REPORT FOR THE CLOSED REGULATORY AUDIT WESTINGHOUSE ELECTRIC COMPANY TOPICAL REPORT WCAP-18904-P/NP, REVISION 0 CRITICAL POWER EXPERIMENTS AND D6 CPR CORRELATION FOR TRITON11 FUEL DOCKET NO. 99902038 EPID: L-2023-TOP-0054
1.0 BACKGROUND
By letter dated November 3, 2023 (Ref. 1), Westinghouse Electric Company (Westinghouse) submitted to the U.S. Nuclear Regulatory Commission (NRC) a request for review and approval of Topical Report (TR) WCAP-18904-P/NP, Revision 0, Critical Power Experiments and D6 CPR Correlation for TRITON11 Fuel (Ref. 2). This TR describes the critical power correlation for TRITON11 fuel. The proposed TR would allow Westinghouse to use the D6 critical power ratio (CPR) correlation on TRITON11 fuel. The NRC staff conducted a regulatory audit to increase efficiency in the review and the development of the NRC staffs safety evaluation (SE).
The scope of this audit included ensuring understanding of the material presented within the TR and discussing draft open items and potential requests for additional information (RAIs).
2.0 REGULATORY AUDIT BASES The regulations at Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A provide general design criteria (GDC) for nuclear power reactors. GDC 10 requires:
The reactor core and associated coolant, control, and protection systems shall be designed with appropriate margin to assure that specified acceptable fuel design limits (SAFDLs) are not exceeded during any condition of normal operation, including the effects of anticipated operational occurrences.
The regulatory guidance provided in NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants (SRP), Section 4.4, Thermal Hydraulic Design (Ref. 3), provides one method commonly used to demonstrate adherence to GDC 10.
SRP 4.4 defines the CPR as the SAFDL and states:
The limiting (minimum) value of DNBR (departure from nucleate boiling ratio),
CHFR (critical heat flux ratio), or CPR correlations is to be established such that at least 99.9 percent of the fuel rods in the core will not experience a DNB (departure from nucleate boiling) or boiling transition during normal operation or AOOs (anticipated operational occurrence).
In summary, 10 CFR Part 50, Appendix A, GDC requires that SAFDLs are used to protect the fuel, and one SAFDL commonly used in boiling water reactors is CPR which demonstrates that 99.9 percent of the fuel rods in the core will not experience a dryout during normal operation or AOOs.
3.0 AUDIT RESULTS The NRC staff conducted a hybrid closed audit of TR WCAP-18904-P/NP, Revision 0, between June 10 and June 14, 2024, virtually and at the Westinghouse facilities in Cranberry, PA, based on the audit plan (Ref. 4).
Discussion of the Topical Report The audit consisted of a detailed walkthrough of TR WCAP-18904-P, Revision 0. The NRC staff used personal notes as well as the TR itself to practice three-way communication, explaining to Westinghouse representatives the NRC staffs understanding of what was stated in the TR. The NRC staff used this opportunity to discuss each of the approximately 30 comprehension questions that were developed from an earlier read-through of the TR. These questions spanned multiple subject matter areas, such as similarity of the D6 correlation to that of the D5, the experimental setup at the FRIGG facility and how CPR data was collected, the general form of the D6 correlation and how this form is consistent with the behavior of thermal-hydraulic phenomena as critical power conditions manifest, and statistical analysis of the collected data when determining predictive uncertainties and ensuring the absence of nonconservative subregions.
Westinghouse representatives provided explanations for each of the comprehension questions in these subject matter areas, enabling the NRC staff to focus on verifying its understanding of material in the TR outside the scope of the comprehension questions. To address this material, the NRC staff and Westinghouse representatives engaged in a methodical, page-by-page progression through the TR contents, identifying material and discussing it as needed. In part, the material the NRC staff discussed with Westinghouse representatives consisted of the justification that the D6 correlation can conservatively estimate critical power values for mass fluxes outside the range of data collected for its development, the transient application of the D6 correlation and why the approach towards implementing it in the BISON-SLAVE channel model is sufficient, and justification the behavior of part length rods is captured. Westinghouse representatives indicated the justifications in these areas are provided within the TR, and the justifications become readily identifiable when consideration is given to the data collection process for CPR correlation development and some inherent principles of thermal-hydraulic behavior. Westinghouse identified the areas within the TR where justification and applicable data was provided.
During the audit, Westinghouse representatives answered all the NRC staffs comprehension and discussion questions. As a result, no open items were identified and no RAIs were developed. Additionally, the justifications and data provided within the TR were pertinent to all the NRC staffs questions. Thus, it was not necessary for the staff to audit any documentation.
The efficiency of this effort afforded the NRC staff additional time during the audit, during which the staff was able to write approximately 75 percent of the draft SE while on site.
During the exit briefing, the NRC staff discussed with Westinghouse representatives the material that was covered in the audit and how it answered all the NRC staffs present questions. The NRC staff indicated that no potential RAIs had been identified, and that a substantial portion of the draft SE had been written. The NRC staff also pointed out that, while no potential RAIs had been identified, a portion of the draft SE remained to be written, during which time some RAIs may be identified. Westinghouse representatives affirmed their understanding and indicated a willingness to support additional audits or clarification telephone calls, as needed.
4.0 PARTICIPANTS Team Member Division Area of Responsibility Kevin Heller NRR1/DSS/SFNB2 Technical Lead Joshua Kaizer NRR/DSS/SFNB Technical Reviewer Jack Vande Polder NRR/DSS/SFNB Technical Reviewer Ekaterina Lenning NRR/DORL/LLPB3 Project Management
5.0 REFERENCES
- 1. Letter from Zachary S. Harper (Westinghouse) to NRC, Submittal of Westinghouse Topical Report WCAP-18904-P/NP, Revision 0, Critical Power Experiments and D6 CPR Correlation for TRITON11 Fuel, LTR-NRC-23-30 dated November 3, 2023 (ADAMS Accession No. ML23307A183 (Publicly Available)).
- 2. Westinghouse, Submittal of WCAP-18904-P/NP, Revision 0, Critical Power Experiments and D6 CPR Correlation for TRITON11 Fuel, dated November 2023 (ADAMS Accession Nos. ML23307A184/ML23307A185 (Proprietary, Non-Publicly Available/Non-proprietary, Publicly Available).
- 3. NRC, NUREG-0800, Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants, Section 4.4, Thermal and Hydraulic Design, Revision 2 dated March 2007 (ADAMS Accession No. ML070550060 (Publicly Available)).
- 4. Letter from Gerond A. George (NRC), to Camille Zozula (Westinghouse), Regulatory Audit Plan for U.S. Nuclear Regulatory Commission Regulatory Audit on June 10-14, 2024, for Review of Westinghouse Topical Report WCAP-18904-P/NP, Revision 0, Critical Power Experiments and D6 CPR Correlation for TRITON11 Fuel (EPID L-2023-TOP-0054), dated May 28, 2024 (ADAMS Accession No. ML24144A225 (Publicly Available)).
1 Office of Nuclear Reactor Regulation (NRR) 2 Division of Safety Systems (DSS)/Nuclear Methods and Fuels Branch (SFNB) 3 Division of Operating Licensees (DORL)/Licensing Projects Branch (LLPB)
SUBJECT:
REPORT FOR THE U.S. NUCLEAR REGULATORY COMMISSION CLOSED REGULATORY AUDIT CONDUCTED ON JUNE 10-14, 2024, FOR THE REVIEW OF WESTINGHOUSE ELECTRIC COMPANY TOPICAL REPORT WCAP-18904-P/NP, REVISION 0, CRITICAL POWER EXPERIMENTS AND D6 CPR CORRELATION FOR TRITON11 FUEL (EPID L-2023-TOP-0054)
DATED OCTOBER 17, 2024 DISTRIBUTION:
PUBLIC RidsNrrDorlLlpb RidsNrrLADHarrison RidsOgcMailCenter RidsACRS_MailCTR RidsNrrDss GGeorge, NRR SKrepel, NRR KHeller, NRR JKaizer, NRR ELenning, NRR RidsNrrDorl RidsResOd RidsNrrDssSfnb ADAMS Accession No.:
ML24278A134 (Cover letter with Enclosed Audit Report)
OFFICE NRR/DORL/LLPB/PM NRR/DORL/LLPB/LA NRR/DSS/SFNB/BC NRR/DORL/LLPB/BC NAME ELenning DHarrison SKrepel GGeorge DATE 10/11/2024 10/16/2024 10/16/2024 10/17/2024 FFICIAL RECORD COPY