05000353/LER-2025-001, HPCI Valve Isolated During a Surveillance Test Due to a Degraded Test Connector
| ML25122A139 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/02/2025 |
| From: | Gillin M Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LG-25-082 LER 2025-001-00 | |
| Download: ML25122A139 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3532025001R00 - NRC Website | |
text
Constellation 10 CFR 50.73 LG-25-082 May 2, 2025 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Limerick Generating Station, Unit 2 Renewed Facility Operating License No. NPF-85 NRC Docket No. 50-353 Subject: LER 2025-001-00 HPCI Valve Isolated During a Surveillance Test Due to a Degraded Test Connector In accordance with the requirements of 10 CFR 50.73(a)(2)(v)(D), Limerick Generating Station hereby submits the enclosed Licensee Event Report.
There are no commitments contained in this letter.
If you have any questions, please contact Jordan Rajan at (610) 718-3400.
Respectfully, Michael F. Gillin Vice President - Limerick Generating Station Constellation Energy Generation, LLC cc: Administrator Region I, USNRC USNRC Senior Resident Inspector, Limerick Generating Station
Abstract
On March 03, 2025, at 10:44 during planned surveillance testing, the High Pressure Coolant Injection (HPCI) system Turbine Exhaust Line Vacuum Breaker Outboard primary containment isolation valve (PCIV) closed. The valve closed due to a degraded cannon plug connector that caused a short within the Emergency Core Cooling System (ECCS) Contact Test Unit being used for the test. The test equipment was removed, and the valve was re-opened. This event is being reported because it resulted in an unplanned inoperability of a single train safety system that could have prevented fulfillment of a safety function.
An eight (8) hour ENS notification was completed on March 03, 2025, at 18:09 (ENS 57582).
Unit Condition Prior to the Event I
- 2. DOCKET NUMBER
- 3. LER NUMBER 353 r::::7 NUMBER NO.
I YEAR SEQUENTIAL REV
~-I 001 1-0 Prior to the event, Unit 2 was in Operational Condition (OPCON) 1 (Power Operation) at approximately 100% power. There were no other structures, systems, or components out of service that contributed to this event.
Description of the Event On March 03, 2025, a surveillance test was being conducted for Unit 2 High Pressure Coolant Injection (HPCI) System (BJ]
to verify that the HPCI logic circuit actuated on a simulated HPCI Steam Supply Pressure-Low signal. At 10:44, the HPCI Turbine Exhaust Line Vacuum Breaker Outboard primary containment isolation valve (PCIV) closed and the HPCI system was declared inoperable.
The test was aborted by removing the ECCS Contact Test Unit (test box), resetting the isolation, and restoring operability of the system. The HPCI System was returned to service on March 03, 2025, at 13:51. An eight (8) hour ENS notification (57582) was completed on March 03, 2025, at 18:09 hours.
Analysis of the Event
The HPCI System was operable during the performance of the instrument testing. The Limerick Technical Specifications allows the system to remain operable for up to eight hours during the instrument testing provided at least one operable channel in the same trip system is monitoring that parameter.
During the instrument testing, when the isolation signal was actuated (Low Steam Line Pressure) the HPCI Turbine Exhaust Line Vacuum Breaker Outboard PCIV closed rendering HPCI inoperable. Immediately following the isolation, the ECCS Contact Test Unit was removed from the HPCI System circuit by unplugging the cannon plug from the panel. Resistance checks were performed of the unit and one electrical short circuit was found. This electrical short circuit resulted in the closure of HPCI Turbine Exhaust Line Vacuum Breaker Outboard PCIV.
Safety Consequence
There was no actual safety consequences associated with this event and the potential safety consequences of this event were minimal. The Reactor Core Isolation {RCIC) System, Automatic Depressurization System (ADS), Residual Heat Removal (RHR) System, and Core Spray (CS) System remained operable during the period that HPCI was inoperable.
This condition resulted in a loss of safety function for the HPCI System and is reportable per 10 CFT 50. 73(a)(2)(v)(D).
Cause of the Event
The cannon plug connector was degraded resulting in a short within the ECCS Contact Test Unit.
Corrective Actions Completed
- 2. DOCKET NUMBER
- 3. LER NUMBER 353 C::7 NUMBER NO.
I YEAR SEQUENTIAL REV
~-, 001 1-0 The ECCS Contact Test Unit was immediately quarantined and the cannon plug connector was replaced.
Corrective Actions Planned
- - Replace cannon plug connectors on all ECCS Contact Test Units.
Previous Similar Occurrences LER 1-2022-001 Unit 1 HPCI Inoperable Due to Inadvertent Isolation Signal Component Data:
System: BJ High Pressure Coolant Injection System Page 3
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