ML18361A583
| ML18361A583 | |
| Person / Time | |
|---|---|
| Site: | Westinghouse |
| Issue date: | 01/09/2019 |
| From: | Ekaterina Lenning NRC/NRR/DLP/PLPB |
| To: | |
| Lenning E, NRR/DLP 415-3151 | |
| Shared Package | |
| ML18318A051 Pkg. | List: |
| References | |
| TAC MF3368 WCAP-17794-NP, WCAP-17794-P | |
| Download: ML18361A583 (5) | |
Text
U.S. NUCLEAR REGULATORY COMMISSION CLOSED AUDIT FOR TOPICAL REPORT WCAP-17794-P, REVISION 0, AND WCAP-17794-NP, REVISION 0, "10X10 SVEA FUEL CRITICAL POWER EXPERIMENTS AND NEW CPR CORRELATIONS: D5 FOR SVEA-96 OPTIMA3" (TAC NO. MF3368)
WESTINGHOUSE ELECTRIC COMPANY BACKGROUND By letter dated November 22, 2013 (Ref. 1), Westinghouse Electric company (Westinghouse) submitted to the U.S. Nuclear Regulatory Commission (NRC) a request for review and approval of WCAP-17794-P, Revision 0, 10x10 SVEA Fuel Critical Power Experiments and New CPR Correlation: D5 for SVEA-96 Optima3 (Ref. 2) a topical report (TR) which describes the critical power correlation for SVEA-96 Optima3 fuel. The proposed TR would allow Westinghouse to use the D5 critical power ratio (CPR) correlation on SVEA-96 Optima3 fuel. The NRC staff has proposed to conduct an audit to discuss Westinghouses response to the NRC request for additional information (RAI) which addresses [
]
The regulations at Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Appendix A provides 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 regulations at SRP 4.4 provides one method commonly used by BWRs to meet 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 (BWRs) 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.
Enclosure 1
The ability to confirm the SAFDL of 99.9 percent was questioned in the review of the D5 model.
[
]
The NRC staff has performed a review of WCAP-17794-P, Revision 0, and all RAI responses, has drafted the safety evaluation, and is in the process of finalizing that safety evaluation. The regulatory audit will be held in accordance with the NRR procedure as described in LIC-111.
REGULATORY AUDIT SCOPE The scope of this audit is to discuss the RAI response [ ] and the draft conditions and limitations which have been previously shared with Westinghouse. Additionally, the NRC staff may discuss questions on the review of WCAP-18032, Calculation of Mixed Core Safety Limit Minimum Critical Power Ratio, if time permits.
The NRC staff would like Westinghouse to make available the appropriate engineer(s) with intimate knowledge of WCAP-17794-P, Revision 0, [ ]
the work Westinghouse has performed to determine the root cause [ ] and can address any comprehension questions by the NRC staff as well as any appropriate references.
TEAM AND REVIEW ASSIGNMENTS The regulatory audit will be held at the Westinghouse facilities in Rockville, MD.
Joshua Kaizer, DSS/SNPB Reed Anzalone, DSS/SNPB Josh Whitman, DSS/SNPB John Lehning, DSS/SNPB Kate Lenning, DLP/PLPB LOGISTICS Audit Dates: Tuesday, December 4, 2018, thru Wednesday, December 5, 2018, and additional follow-up telephone calls as needed.
Westinghouse should provide a conference room for discussions.
DELIVERABLES A regulatory audit summary will be provided within 90 days of the completion of the audit.
REFERENCES
- 1. Letter from James A. Gresham (W) to U.S. NRC, Submittal of WCAP-17794-P, Revision 0 and WCAP-17794-NP, Revision 0, 10x10 SVEA Fuel Critical Power Experiments and New CPR Correlation: D5 for SVEA-96 Optima3, November 22, 2013 (ADAMS Accession No. ML13333A274).
- 2. Bergmann, U., Hemlin, M., Bergman, K., and LeCorre, J.M., 10x10 SVEA Fuel Critical Power Experiments and New CPR Correlation: D5 for SVEA-96 Optima3, WCAP-17794-P/NP, November 2013 (ADAMS Accession No. ML13333A276 /
ML13333A275 (Non-Publicly Available/Publicly Available)).
Appendix A - Technical Issues The audit will focus on the following 4 main topics:
(1) Definition of [
]
(2) Occurrence of [
]
(3) Restricted domain of D5. From both technical and regulatory perspective, restrictions on [
]
(4) Other applicable data. What is the applicability of inspection data [
] It does not seem like there would be any additional experimental data in that domain or operation data in that domain. Is Westinghouse aware of any additional data for that domain?
Enclosure 1
Additional topics/questions:
- Discussion on proprietary information withholding for SE. What can NRC staff discuss with other vendors?
- Provide an indication of where the recirculation headers are located relative to Figure 4-14 from the July 2018 RAI response.
- Discussion of whether tests that show flow equalization between SVEA sub-bundles apply to a condition where [ ] are applied to the sub-bundles.
- How thick are the thin and thick films discussed in RAI response?
- How thick are the films expected to be in the upper portion of the bundle prior to reaching the spacer grid elevation?
- Discussion of phenomenon occurring at the fuel rod surface on [
] and how it is similar to and different from dryout as modeled in D5.
- Discussion of details regarding the [
]
- To what extent does the evidence from [
]