ENS Event | |
|---|---|
19:59 Jun 8, 2026 | |
| Title | Invalid Specified System Actuation |
| Event Description | The following information was provided by the licensee via phone and email:
On June 8, 2026, at 1259 PDT, Columbia Generating Station's leak detection monitor '1A' (LD-MON-1A) caused an isolation of RWCU-V-4 (reactor water cleanup outboard isolation valve) and RCIC-V-8 (reactor core isolation cooling outboard steam supply isolation valve). Based on a review of available information by engineering, the actuations were determined to be invalid and likely the result of an intermittent nuclear measurement analysis and control (NUMAC) bus communication fault as plant conditions for a valid actuation did not exist. The actuation was not initiated in response to actual plant conditions, this was not an intentional manual initiation, and there were no parameters satisfying the requirements for initiation. Therefore, this event has been determined to be an invalid actuation. As indicated in 10 CFR 50.73(a)(1), in the case of an invalid actuation reported under 10 CFR 50.73(a)(2)(iv)(A), the licensee may, at its option, provide a telephonic notification to the NRC Operations Center within 60 days of discovery of the event instead of submitting a written licensee event report. This 60-day telephone notification is being made in accordance with 10 CFR 50.73(a)(1) for invalid actuations reported under 10 CFR 50.73 (a)(2)(iv)(A). There was no impact on the health and safety of the public or plant personnel. The following information is provided as specified in NUREG-1022: (a) Containment Isolation Valves RWCU-V-4 and RCIC-V-8 isolated. (b) All expected isolations based on the as-found condition of the leak detection monitor were completed. (c) The isolation of RWCU-V-4 and RCIC-V-8 completed successfully. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
Columbia  Washington (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation | |
| Time - Person (Reporting Time:+1239.52 h51.647 days <br />7.378 weeks <br />1.698 months <br />) | |
| Opened: | Jerry Ainsworth 11:30 Jul 30, 2026 |
| NRC Officer: | Karen Cotton |
| Last Updated: | Jul 30, 2026 |
| 58388 - NRC Website
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Unit 2 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |
WEEKMONTHYEARENS 583882026-06-08T19:59:0008 June 2026 19:59:00
[Table view]10 CFR 50.73(a)(1), Submit an LER Invalid Specified System Actuation ENS 566252023-05-17T10:39:00017 May 2023 10:39:00 10 CFR 50.73(a)(1), Submit an LER 60-DAY Optional Telephonic Notification for an Invalid Actuation of an Emergency AC Electrical Power System ENS 528692017-05-25T23:47:00025 May 2017 23:47:00 10 CFR 50.73(a)(1), Submit an LER Invalid High Pressure Core Spray (Hpcs) System Actuation in Mode 5 ENS 494602013-08-23T14:54:00023 August 2013 14:54:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Primary Containment Isolation Valve Actuation ENS 481392012-05-31T12:35:00031 May 2012 12:35:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Optional Telephonic Notification for an Invalid Primary Containment Isolation Valve Actuation ENS 469772011-04-23T15:14:00023 April 2011 15:14:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation Due to Unrecognized Design Conflict ENS 469722011-04-21T20:10:00021 April 2011 20:10:00 10 CFR 50.73(a)(1), Submit an LER Invalid Primary Containment Isolation System Actuation Due to Conflicting Work Activities ENS 468972011-04-01T04:28:0001 April 2011 04:28:00 10 CFR 50.73(a)(1), Submit an LER 60-Day Telephonic Notification of Invalid Specified System Actuation 2026-06-08T19:59:00 | |