ML25219A177
| ML25219A177 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 08/07/2025 |
| From: | Gillin M Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| G-25-119, TS 3.3.7.5 | |
| Download: ML25219A177 (1) | |
Text
Constellation..
LG-25-119 August 7, 2025 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Wilmington, DC, 20555-0001 Limerick Generating Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353 TS 3.3.7.5
Subject:
Special Report - Accident Monitoring Instrumentation lnoperability This Special Report is being submitted pursuant to the requirements of Limerick Generating Station (LGS), Unit 1 and Unit 2 Technical Specification 6.9.2, and Technical Specification 3.3.7.5, table 3.3.7.5-1, Action 81. Action 81 states the following:
ACTION 81 - With the number of OPERABLE accident monitoring instrumentation channels less than required by the Minimum Channels OPERABLE requirement, initiate the preplanned alternate method of monitoring the appropriate parameters within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, and
- a. Either restore the inoperable channel(s) to OPERABLE status within 7 days of the event, or
- b. Prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within 14 days following the event outlining the action taken, the cause of the inoperability and the plans and schedule for restoring the system to OPERABLE status.
On July 24, 2025, at 10:41 hours, the Wide Range Accident Monitor (WRAM) was declared inoperable due to the Mid-Range channel failing the source check.
Actions taken:
Operations verified the affected system isolation valves were closed as required by TS 3.3.2 Isolation Actuation Instrumentation, Table 3.3.2-1, Action 23.
Operations also initiated the preplanned alternate method of monitoring required by TS 3.3.7.5 Accident Monitoring Instrumentation, Table 3.3.7.5-1, Action 81.
Maintenance troubleshooting identified a defective line amplifier and pre-amplifier board for the mid-range detector.
The line amplifier and pre-amplifier board were replaced and successfully tested.
Cause of the lnoperability:
Initial troubleshooting identified intermittent issues with a line amplifier and a pre-amplifier board located in the Power Supply Shielded Enclosure. During post-maintenance testing, the Main Control Room Hi and Hi-Hi alarms failed to annunciate.
The likely cause of the malfunction is either the signal conditioner card or the RM-80 computer is degraded.
Plans and schedule for restoring the system to operable:
Test the output signal conditioner and the RM-80 computer.
Assess annunciator and light circuit integrity.
Identify and perform additional troubleshooting actions.
Complete the surveillance test that failed.
Return the system to service by August 14, 2025.
There are no regulatory commitments contained in this letter.
If you have any questions, please contact Jordan Rajan at (610) 718-3400.
Respectfully, Michael Gillin Site Vice President - Limerick Generating Station Constellation Energy Generation, LLC cc: Administrator Region I, USNRC USNRC Senior Resident Inspector, Limerick Generating Station