ML24305A174
| ML24305A174 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 10/31/2024 |
| From: | Georgeson C South Texas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NOC-AE-24004078, STI: 35662300 | |
| Download: ML24305A174 (1) | |
Text
~
Nuclear Operating Company ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 October 31, 2024 NOC-AE-24004078 10 CFR 50.46 STI: 35662300 South Texas Project Unit 1 Docket No. STN 50-498 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes In accordance with the requirements of 10 CFR 50.46(a)(3)(ii), STP Nuclear Operating Company (STPNOC) is submitting a 30-day report for a significant change in the South Texas Unit 1 Emergency Core Cooling Model.
For Unit 1 Cycle 26, there is a large break loss-of-coolant-accident (LBLOCA) Peak Clad Temperature (PCT) penalty of 8°F due to the gamma energy deposition model (GEOM). The total PCT for Unit 1 LBLOCA is 2131°F. See enclosure for the detailed PCT Summary.
Since the absolute value of the PCT changes from the analysis of record for Unit 1 Cycle 26 exceeds 50°F, the change is considered significant in accordance with 10 CFR 50.46(a)(3)(i).
No schedule for reanalysis is proposed, since the Unit 1 Cycle 26 PCT remains below the 10 CFR 50.46(b)(1) limit of 2200°F.
There are no commitments in this letter.
If there are any questions regarding this information, please contact Zachary Dibbern at 361-972-4336 or me at 361-972-7806.
~JI.
Chris eorgeso General Manager, Strategic Projects and Engineering Design
Enclosure:
Evaluation of the South Texas Project Unit 1 Cycle 26 LOCA RSAC GEOM Violation cc:
Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511
Enclosure NOC-AE-24004078 Page 1 of 2 EVALUATION OF THE SOUTH TEXAS PROJECT UNIT 1 CYCLE 26 LOCA RSAC GEDM VIOLATION
Background
The South Texas Project Unit 1 Cycle 26 reload core design resulted in a violation of the gamma energy deposition model (GEDM) loss-of-coolant accident (LOCA) reload safety analysis checklist (RSAC) limit used in the large-break LOCA analysis. This violation was evaluated for South Texas Project Unit 1 Cycle 26 and represents a change in a plant configuration or associated set point(s), distinguished from an evaluation model change in Section 4 of WCAP-13451.
Affected Evaluation Models(s) 1981 Westinghouse Large Break LOCA Evaluation Model with BASH Estimated Effect The impact of the Cycle 26 GEDM violation was estimated to result in an 8°F increase to the calculated large-break LOCA peak cladding temperature (PCT) for South Texas Project Unit 1.
Enclosure NOC-AE-24004078 Page 2 of 2 Westinghouse LOCA Peak Clad Temperature Summary Plant Name:
SOUTH TEXAS 1 Utility Name:
STPNOC EM:
BASH AOR
Description:
Appendix K Large Break Summary Sheet Status Cycle 26 PCT (°F)
ANALYSIS-OF-RECORD 2090 ASSESSMENTS Delta PCT
(°F)
- 1. IMP Database Error Corrections 0
- 2. PAD Version 4.0 Implementation
-30
- 3. LOCBART Pellet Volumetric Heat Generation Rate 6
- 6. Effect of Containment Purge 6
- 7. Rebaseline of AOR 46
- 8. GEDM Violation Evaluation 8