U-604855, Special Report: Inoperable Drywell High Range Gamma Radiation Monitor
| ML25323A254 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 11/17/2025 |
| From: | Sterio A Constellation Energy Generation |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| U-604855 | |
| Download: ML25323A254 (1) | |
Text
Clinton Power Station 8401 Power Road Clinton, IL 61727 Constellation1 U-604855 November 17, 2025 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D.C. 20555-0001 Clinton Power Station, Unit 1 Facility Operating License No. NPF-62 NRC Docket No. 50-461
Subject:
Special Report: Inoperable Drywell High Range Gamma Radiation Monitor
References:
Letter U-604787 - Special Report: Drywell High Range Gamma Radiation Monitor," dated November 21, 2023.
In accordance with Clinton Power Station (CPS) Technical Specification (TS) 3.3.3.1, Post Accident Monitoring (PAM) Instrumentation, Required Action 8.1, Constellation Energy Generation, LLC (CEG) is submitting the following Special Report concerning the inoperability of Drywell High Range Gamma Radiation Monitor, 1 RIX-CM060.
Description of Event On October 2, 2025, at 0804 hours0.00931 days <br />0.223 hours <br />0.00133 weeks <br />3.05922e-4 months <br />, 1 RIX-CM060 DRYWELL HIGH RANGE GAMMA RADIATION MONITOR was inoperable upon entry into Mode 2 from Mode 4 for plant startup from refuel outage C1 R22 (Fall 2025). Due to this condition, LCO 3.0.4.a was utilized to allow for the mode change and TS 3.3.3.1 required action A.1 was entered at that time. The 30-day completion time for TS 3.3.3.1 required action A.1 was exceeded on November 1, 2025 at 0804, requiring entry into TS 3.3.3.1 required action 8.1 which states, "Initiate action to prepare and submit a Special Report" immediately. Per TS 3.3.3.1 required action 8.1 bases, "This Special Report shall be submitted in accordance with 10 CFR 50.4 within 14 days of entering Condition 8."
1 RIX-CM060 had been previously declared inoperable during refuel outage C1 R21 (Fall 2023) with TS 3.3.3.1 required actions A.1 and 8.1 entered on October 08, 2023 and November 7, 2023 respectively.
Action Taken Troubleshooting over multiple days during refuel outage C1 R21 determined an issue existed with the detector for 1 RIX-CM060. IMO was unable to obtain a new detector prior to Drywell closeout and startup from C 1 R21, and the decision was made to back out of the maintenance and correct in the next available station outage due to having 1 RIX-CM059 in service. Additional troubleshooting and restoration was to be performed during the next forced outage or refueling outage C 1 R22 due to radiation considerations.
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Page 2 U-604855 During refuel outage C1 R22, work order 5415532 was improperly assessed for Technical Specification impacts prior to removing it from outage scope. Contributing to this, the station missed an opportunity to code the corrective maintenance as regulatory following the special report submitted to the NRC in 2023.
Currently, an adequate alternate method of monitoring drywell gamma radiation exists with 1 RIX-CM059 remaining operable. Corrective Action Program AR 4914716 will drive to make the necessary repairs to 1 RIX-CM060 at the next reasonable opportunity.
Cause of lnoperability Trouble shooting has determined that the most likely cause of inoperability is due to an issue with the detector for 1 RIX-CM060.
There are no regulatory commitments contained in this letter. Should you have any questions concerning this report, please contact Mr. Derek Hillinger, Regulatory Assurance Manager, at (217) 937-2800.
Respectfully,
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Alexander Sterio Acting Site Vice President Clinton Power Station cc:
Regional Administrator-NRC Region Ill NRC Senior Resident Inspector - Clinton Power Station Office of Nuclear Facility Safety -