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# | {{Adams | ||
| number = ML21340A257 | |||
| issue date = 12/06/2021 | |||
| title = 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes | |||
| author name = Georgeson C | |||
| author affiliation = South Texas Project Nuclear Operating Co | |||
| addressee name = | |||
| addressee affiliation = NRC/Document Control Desk, NRC/NRR | |||
| docket = 05000498 | |||
| license number = | |||
| contact person = | |||
| case reference number = NOC-AE-21003858 | |||
| document type = Letter | |||
| page count = 2 | |||
}} | |||
=Text= | |||
{{#Wiki_filter:December 6, 2021 NOC-AE-21003858 10 CFR 50.46 (a)(3)(i) 10 CFR 50.46 (a)(3)(ii) | |||
STI: 35252800 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 South Texas Project Unit 1 Docket No. STN 50-498 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes | |||
==References:== | |||
: 1. Letter from M. Page to NRC Document Control Desk, South Texas Project Units 1 & 2 10 CFR 50.46 Annual Report of ECCS Model Revisions, March 4, 2019, NOC-AE-19003627, ML19063D875. | |||
: 2. Letter from D. Roland to NRC Document Control Desk, South Texas Project Unit 1 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes, June 17, 2020, NOC-AE-20003738, ML20169A859. | |||
: 3. Letter from Dennis J. Galvin (NRC) to G.T. Powell, "South Texas Project, Unit 1 - | |||
Issuance of Amendment No. 219 to Revise Technical Specifications to Reduce Safety Injection Accumulators Minimum Pressures (Exigent Circumstances) | |||
(EPID L-2020-LLA-0108)," May 28, 2020, AE-NOC-20003255, ML20141L612. | |||
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. | |||
In Unit 1 Cycle 23, South Texas Project Unit 1 had reduced the Technical Specification minimum accumulator cover gas pressure to 500 psig to mitigate the effects of check valve leakage into the Low Head Safety Injection / Residual Heat Removal Header. This resulted in an estimated 3°F increase in Peak Clad Temperature (PCT) to the previous value of 2123°F as reported in Reference 1 for the limiting Emergency Core Cooling System (ECCS) analysis for the large break loss-of-coolant-accident (LBLOCA). The PCT value for Unit 1 Cycle 23 was 2126°F as stated in References 2 and 3. | |||
For Unit 1 Cycle 24, the check valve leakage issue was remedied and the Technical Specification minimum nitrogen cover-pressure limit of all three Safety Injection Accumulators has been changed back to 590 psig. As a result, the PCT value for Unit 1 Cycle 24 is restored to 2123°F. The sum of the absolute magnitudes of all the individual changes is 93°F as listed in the enclosed table (Delta PCT column). Since the sum of the absolute magnitudes of the PCT changes from the analysis of record for Unit 1 Cycle 23 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 24 PCT remains below the 10 CFR 50.46(b)(1) limit of 2200°F. | |||
NOC-AE-21003858 Page 2 of 2 There are no commitments in this letter. | |||
If there are any questions regarding this information, please contact Tim Hammons at 361-972-7347 or me at 361-972-7806. | |||
(!£! | |||
General Manager, Engineering th | |||
==Enclosure:== | |||
Unit 1 Cycle 24 Westinghouse LOCA Peak Clad Temperature Summary cc: | |||
Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511 | |||
Enclosure NOC-AE-21003858 Page 1 of 1 Unit 1 Cycle 24 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 24 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 | |||
: 4. PWROG TCD Evaluation - Rebaseline of AOR 5 | |||
: 5. PWROG TCD Evaluation - Effect of TCD and 0 Assembly Power/Peaking Factor Burndown | |||
: 6. Effect of Containment Purge 6 | |||
: 7. Rebaseline of AOR 46 AOR + ASSESSMENTS PCT = 2123 °F}} |
Latest revision as of 23:14, 1 March 2022
ML21340A257 | |
Person / Time | |
---|---|
Site: | South Texas |
Issue date: | 12/06/2021 |
From: | Georgeson C South Texas |
To: | Document Control Desk, Office of Nuclear Reactor Regulation |
References | |
NOC-AE-21003858 | |
Download: ML21340A257 (2) | |
Text
December 6, 2021 NOC-AE-21003858 10 CFR 50.46 (a)(3)(i) 10 CFR 50.46 (a)(3)(ii)
STI: 35252800 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 South Texas Project Unit 1 Docket No. STN 50-498 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes
References:
- 1. Letter from M. Page to NRC Document Control Desk, South Texas Project Units 1 & 2 10 CFR 50.46 Annual Report of ECCS Model Revisions, March 4, 2019, NOC-AE-19003627, ML19063D875.
- 2. Letter from D. Roland to NRC Document Control Desk, South Texas Project Unit 1 10 CFR 50.46 Thirty-Day Report of Significant ECCS Model Changes, June 17, 2020, NOC-AE-20003738, ML20169A859.
- 3. Letter from Dennis J. Galvin (NRC) to G.T. Powell, "South Texas Project, Unit 1 -
Issuance of Amendment No. 219 to Revise Technical Specifications to Reduce Safety Injection Accumulators Minimum Pressures (Exigent Circumstances)
(EPID L-2020-LLA-0108)," May 28, 2020, AE-NOC-20003255, ML20141L612.
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.
In Unit 1 Cycle 23, South Texas Project Unit 1 had reduced the Technical Specification minimum accumulator cover gas pressure to 500 psig to mitigate the effects of check valve leakage into the Low Head Safety Injection / Residual Heat Removal Header. This resulted in an estimated 3°F increase in Peak Clad Temperature (PCT) to the previous value of 2123°F as reported in Reference 1 for the limiting Emergency Core Cooling System (ECCS) analysis for the large break loss-of-coolant-accident (LBLOCA). The PCT value for Unit 1 Cycle 23 was 2126°F as stated in References 2 and 3.
For Unit 1 Cycle 24, the check valve leakage issue was remedied and the Technical Specification minimum nitrogen cover-pressure limit of all three Safety Injection Accumulators has been changed back to 590 psig. As a result, the PCT value for Unit 1 Cycle 24 is restored to 2123°F. The sum of the absolute magnitudes of all the individual changes is 93°F as listed in the enclosed table (Delta PCT column). Since the sum of the absolute magnitudes of the PCT changes from the analysis of record for Unit 1 Cycle 23 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 24 PCT remains below the 10 CFR 50.46(b)(1) limit of 2200°F.
NOC-AE-21003858 Page 2 of 2 There are no commitments in this letter.
If there are any questions regarding this information, please contact Tim Hammons at 361-972-7347 or me at 361-972-7806.
(!£!
General Manager, Engineering th
Enclosure:
Unit 1 Cycle 24 Westinghouse LOCA Peak Clad Temperature Summary cc:
Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511
Enclosure NOC-AE-21003858 Page 1 of 1 Unit 1 Cycle 24 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 24 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