05000498/LER-2024-006, Condition Prohibited by Technical Specifications and Potential Loss of Safety Function Due to Inoperable Pressurizer Power Operated Relief Valve
| ML24358A097 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 12/23/2024 |
| From: | Tomlinson J South Texas |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NOC-AE-24004083 LER 2024-006-00 | |
| Download: ML24358A097 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4982024006R00 - NRC Website | |
text
December 23, 2024 NOC-AE-24004083 10 CFR 50.73 STI: 35686095 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 South Texas Project Unit 1 Docket No. STN 50-498 Licensee Event Report 2024-006-00 Condition Prohibited by Technical Specifications and Potential Loss of Safety Function Due to Inoperable Pressurizer Power Operated Relief Valve Pursuant to reporting requirements in 10 CFR 50.73(a)(2)(i)(B) and 10 CFR 50.73(a)(s)(v)(D),
STP Nuclear Operating Company (STPNOC) hereby submits the attached Licensee Event Report 2024-006-00 for South Texas Project Unit 1.
The event did not have an adverse effect on the health and safety of the public.
There are no commitments in this submittal.
If there are any questions regarding this submittal, please contact Chris Warren at (361) 972-7293 or me at (361) 972-8945.
Jason R. Tomlinson Site Vice President Attachment: Unit 1 LER 2024-006-00, Condition Prohibited by Technical Specifications and Potential Loss of Safety Function Due to Inoperable Pressurizer Power Operated Relief Valve cc:
Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 E. Lamar Boulevard Arlington, TX 76011-4511 Jason Tomlinson Digitally signed by Jason Tomlinson Date: 2024.12.23 08:12:07 -06'00'
NOC-AE-24004083 Attachment Attachment Unit 1 LER 2024-006-00 Unit 1 LER 2024-006-00, Condition Prohibited by Technical Specifications and Potential Loss of Safety Function Due to Inoperable Pressurizer Power Operated Relief Valve
Abstract
South Texas Unit 1
00498 8
Condition Prohibited by Technical Specifications and Potential Loss of Safety Function Due to Inoperable Pressurizer Power Operated Relief Valve 10 22 2024 2024 006 00 12 23 2024 3
000
Chris Warren, Licensing Engineer 361-972-7293 B
AB PSV EMERSO Y
03 27 2025 On October 5, 2024, while in MODE 3, STP Unit 1 Pressurizer Power Operated Relief Valve (PORV) PCV-0656A failed to open from the Control Room hand switch and Auxiliary Shutdown Panel during performance of an operability test. Initial troubleshooting identified a partially disengaged fastener that is used to connect a wire from the PORV solenoid to its power source. The event was determined to have resulted in inoperability of the valve following installation of a replacement solenoid valve in November 2021. This resulted in a condition prohibited by Technical Specification 3.4.4, Actions 'b' and 'c' and a condition that could have prevented fulfillment of a safety function of the Pressurizers, specifically control of Reactor Coolant System pressure during a Small Break Loss of Cooling Accident, due to multiple occurrences of both Pressurizer PORVs being inoperable from November 2021 until October 2024. Corrective maintenance to restore PORV PCV-0656A to OPERABLE status has been completed. Extent of condition inspections to ensure the condition does not exist on the remaining Pressurizer PORV for the Unit 1 and spare PORVs have been completed. Unit 2 Pressurizer PORV inspections are planned for the next scheduled refueling outage. A causal investigation is scheduled to determine any additional causes of the event and corrective actions and will be provided in a supplement to this report.Page of
- 3. LER NUMBER YEAR SEQUENTIAL NUMBER REV NO.
052 050
- 4. Planned - Modify procedure 0PMP04-RC-0028, Pressurizer Power Operated Relief Valve Maintenance, to include instructions to test for loose wiring in the term block from the vendor as discovered in 1RE25. Ensure that the check is performed before the solenoid leak check.
A causal investigation is scheduled to determine if any additional corrective actions are needed and will be provided in a supplement to this report.
VI. Previous Similar Events
- 1. STP Unit 1 LER 2023-001-00, Unit 1 Pressurizer Power Operated Relief Valve Failed to Open, June 12, 2023, (NOC-AE-23003967)(ML2316A248) [PORV PCV-0656A]
- 2. STP Unit 1 LER 2023-001-01 supplement, Unit 1 Pressurizer Power Operated Relief Valve Failed to Open, July 26, 2023, (NOC-AE-23003977)(ML23207A220) [PORV PCV-0656A]
- 3. Condition Report (CR) 21-10369 - During performance of surveillance testing, Unit 1 Pressurizer PORV PCV-0656A did not stroke.
- 4. CR 24-2037 - Unit 1 Pressurizer PORV PCV-0656A failed to stroke from the Control Room handswitch and auxiliary shutdown panel during the performance of 0PSP03-RC-0010.
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South Texas Unit 1 00498 2024 006 00