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The following information was provided by … The following information was provided by the licensee via phone and email:</br>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). </br>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.</br>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.</br>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).</br>There was no impact on the health and safety of the public or plant personnel.</br>The following information is provided as specified in NUREG-1022: </br>(a) Containment Isolation Valves RWCU-V-4 and RCIC-V-8 isolated.</br>(b) All expected isolations based on the as-found condition of the leak detection monitor were completed.</br>(c) The isolation of RWCU-V-4 and RCIC-V-8 completed successfully.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified. +
19:59:00, 8 June 2026 +
58,388 +
11:30:00, 30 July 2026 +
19:59:00, 8 June 2026 +
The following information was provided by … The following information was provided by the licensee via phone and email:</br>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). </br>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.</br>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.</br>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).</br>There was no impact on the health and safety of the public or plant personnel.</br>The following information is provided as specified in NUREG-1022: </br>(a) Containment Isolation Valves RWCU-V-4 and RCIC-V-8 isolated.</br>(b) All expected isolations based on the as-found condition of the leak detection monitor were completed.</br>(c) The isolation of RWCU-V-4 and RCIC-V-8 completed successfully.</br>The NRC Resident Inspector has been notified. NRC Resident Inspector has been notified. +
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00:00:00, 30 July 2026 +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
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51.647 d (1,239.52 hours, 7.378 weeks, 1.698 months) +
19:59:00, 8 June 2026 +
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