GNRO-2021/00037, 2021 Annual Report of Changes and Errors to 10 CFR 50.46 Analysis Grand Gulf Nuclear Station, Unit 1
| ML21334A286 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 11/30/2021 |
| From: | Hardy J Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GNRO-2021/00037 | |
| Download: ML21334A286 (3) | |
Text
Entergy Operations, Inc.
P.O. Box 756 Port Gibson, Mississippi 39150 Jeffery A. Hardy Manager Regulatory Assurance Grand Gulf Nuclear Station Tel: 802-380-5124 10 CFR 50.46 GNRO-2021/00037 November 30, 2021 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUBJECT:
2021 Annual Report of Changes and Errors to 10 CFR 50.46 Analysis Grand Gulf Nuclear Station, Unit 1 NRC Docket No. 50-416 Renewed Facility Operating License No. NPF-29
REFERENCE:
- 1. Entergy letter to NRC, GNRO-2020/000, 2020 Report of Changes and Errors to 10CFR50.46, dated December 16, 2020 (ADAMS Accession No. ML20351A255).
In accordance with 10 CFR 50.46(a)(3)(ii), Grand Gulf Nuclear Station, Unit 1 (GGNS), is required to report to the Nuclear Regulatory Commission, at least annually, the estimated effect on the limiting Emergency Core Cooling System (ECCS) analysis caused by changes to, or errors discovered in, the accepted ECCS evaluation model.
Since the last 10 CFR 50.46(a)(3)(ii) report, dated December 16, 2020 [Reference 1], through December 1, 2021, there have been two errors identified. The table below summarizes the effects of the two recent notifications 2021-01 and 2021-02 to the GGNS ECCS analysis performed by General Electric-Hitachi Nuclear Energy (GEH) for the current reporting period.
The current Licensing Basis peak clad temperature (PCT) results in a projected current PCT approximately 1715°F. This is below the 2200°F acceptance criterion of 10 CFR 50.46.
GNRO-2021/00037 Page 2 of 3 Evaluation Model: SAFER/PRIME-LOCA Notification Nature of Change or Error to 10 CFR 50.46 Estimated PCT Effect (PCT) 2021-01 The fuel pellet to plenum spring conductance is an input to the fuel rod stress and perforation model in ECCS LOCA calculations. The error only affects the temperature and plenum gas pressure calculation in the plenum region, outside of the active fuel region. The error has an insignificant effect on the rod internal pressure calculation because the heat capacity of the spring is much smaller when compared to the fuel stored energy and decay heat. An assessment was performed for a span of representative plants with the SAFER evaluation model. Using the correct input value to SAFER for the fuel pellet to plenum spring conductance parameter, the results confirmed an insignificant PCT impact for affected fuel types.
0oF 2021-02 The inner cladding surface roughness is an input to the gap conductance model. An inconsistency was identified between the roughness value used in fuel performance model PRIME and the input to the SAFER and TRACG calculations. The inner cladding surface roughness affects the pellet-cladding contact heat transfer and therefore, the gap conductance.
The input inconsistency is small and should have an insignificant effect on the ECCS LOCA calculations. An assessment was performed for a span of representative plants with the SAFER and TRACG evaluation models. Using consistent values for the inner cladding surface roughness input to SAFER and TRACG, the results confirmed an insignificant PCT impact for affected fuel types.
0oF Sum of Absolute Magnitude of Error During this Period.
0oF This letter contains no new Regulatory Commitments. Should you have any questions concerning the content of this letter, please contact Jeff Hardy, Regulatory Assurance Manager at 802-380-5124.
Sincerely, Digitally signed by Jeff Hardy Date: 2021.11.30 10:03:55 -06'00' JAH/fas Attachments: None.
cc:
NRC Senior Resident Inspector Grand Gulf Nuclear Station Port Gibson, MS 39150 Jeff Hardy
GNRO-2021/00037 Page 3 of 3 U.S Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001