05000498/LER-2023-004-01, Condition Prohibited by Technical Specifications Due to Inoperable Train of Essential Chilled Water
| ML24116A317 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/25/2024 |
| From: | Tomlinson J South Texas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NOC-AE-24004030, 35580872 LER 2023-004-01 | |
| Download: ML24116A317 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 4982023004R01 - NRC Website | |
text
Glrrr Hucleer Opercllng ortpany U
r April25,2024 NOC-AE-24004030 10 cFR 50.73 STI: 35580872 File No. G26 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Reference Attachment.
Regional Administrator, Region lV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 7601 1 -451 1 South Texas Project Unit 1 Docket No. STN 50498 Licensee Event Report 2023-004-01 Supplement to Condition Prohibited by Technical Specifications Due to lnooerable Train of Essential Chilled Water Letter; A. Capristo (STP) to Document Control Desk (NRC); "Licensee Event Report 2023-004-00 Condition Prohibited by Technical Specifications Due to lnoperable Train of Essential Chilled Water;" February 5,2024; (NOC-AE-24004012)
(M1240364352).
Pursuant to reporting requirements of 10 CFR 50.73(aX2)(iXB), STP Nuclear Operating Company (STPNOC) hereby submits the supplemented South Texas Project (STP) Unit 1 Licensee Event Report (LER) 2023-004-01.
The event did not have an adverse effect on the health and safety of the public.
There are no commitments in this submittal.
lf there are any questions on this submittal, please contact Walter Fulton al361-972-4349 or me al361-972-8945.
/7^
Jason R. Tomlinson Site Vice President LER 2023-004-01, Supplement to Condition Prohibited by Technical Specifications Due to lnoperable Train of Essential Chilled Water cc:
NOC-AE-24004030 Attachment Attachment LER 2023-004-01 Supplement to Condition Prohibited by Technical Specifications Due to Inoperable Train of Essential Chilled Water
Abstract
South Texas, Unit 1
00498 4
Condition Prohibited by Technical Specifications Due to Inoperable Train of Essential Chilled Water 11 27 2023 2023 004 01 04 25 2024 1
100
Walter Fulton / Specialist Engineer Consulting (361) 972-4349 A
KM CHU Y018 Yes
On 11/20/23 at 1530 Essential Chiller 12C was declared OPERABLE following maintenance. The following day at 1245, Train 'C' Essential Chilled Water System (EChWS) was declared inoperable due to excessive chilled water leakage. A subsequent Engineering evaluation determined that due to the leakage, Train 'C' EChWS should be considered inoperable from the date and time the 12C Essential Chiller was restored from maintenance and declared OPERABLE. With only two EChWS loops OPERABLE, Technical Specification (TS) 3.7.14 Action a requires restoration of the inoperable loop within 7 days or application of the Configuration Risk Management Program (CRMP), or to be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. The Engineering evaluation determined that Train 'C' EChWS was inoperable without any of the required TS actions taken from 1530 on 11/20/23 to 1245 on 11/28/23 when the CRMP was entered. This is a total of 189 hours0.00219 days <br />0.0525 hours <br />3.125e-4 weeks <br />7.19145e-5 months <br /> and 15 minutes which exceeds the 174 hours0.00201 days <br />0.0483 hours <br />2.876984e-4 weeks <br />6.6207e-5 months <br /> (7 days plus 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />) allowed by the TS. Therefore, this event is reportable under 10 CFR 50.73(a)(2)(i)(B) as a condition which is prohibited by the plant's TS.
Summary of the Event Timeline (Note: All times are Central Standard Time) 11/10/23 (1413) - Essential Chilled Water 'C' train declared inoperable due to exceeding the maximum compressor discharge pressure.
11/17/23 (0642) - Entered CRMP.
11/20/23 (1530) - Essential Chilled Water C train declared OPERABLE following completion of maintenance and successful post-maintenance testing. Technical Specification 3.7.14 and CRMP exited.
11/21/23 (1245) - Essential Chilled Water C train declared inoperable due to excessive chilled water leakage.
11/28/23 (1245) - Entered CRMP.
12/03/23 (2254) - Essential Chilled Water C train declared OPERABLE, Technical Specification 3.7.14 and CRMP exited.
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South Texas, Unit 1 00498 2023 004 01Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
C. Safety Consequences and Implications
A risk evaluation was performed to estimate the Incremental Core Damage Probability (ICDP) associated with this event.
The calculated ICDP is above the Non-Risk Significant threshold but below the Potentially Risk Significant threshold.
The event did not result in any offsite release of radioactivity or increase of offsite dose rates and there were no personnel injuries or damage to any other safety-related equipment associated with this event.
Therefore, there was no adverse effect on the health and safety of the public.
IV. Cause of Event
Station troubleshooting processes were not used to evaluate the inventory loss associated with Essential Chiller 12C.
V. Corrective Actions
- 1. Complete an evaluation on processes used by Operations, Engineering, and Maintenance to ensure the troubleshooting process is entered appropriately.
VI. Previous Similar Events
STP Nuclear Operating Company submitted two Licensee Event Reports in January 2024 associated with the Essential Chilled Water System. Unit 1 LER 2023-003-00 was submitted on 01/09/24 and Unit 2 LER 2023-001-00 was submitted on 01/15/24. Each event was reported under 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented fulfillment of a safety function which is a different reporting criteria than this event (10 CFR 50.73(a)(2)(i)(B)). STPNOC has performed additional evaluations to determine if any common causes exist between this event and the other two Essential Chilled Water System events.
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South Texas, Unit 1 00498 2023 004 01