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The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 0127 EDT on 9/17/2024, with Unit 3 in mode 1 at 100% power, the reactor automatically tripped due to the passive residual heat removal heat exchanger outlet flow control valve failing open. A manual safeguards actuation was initiated due to the lowering pressurizer water level resulting from the reactor coolant system cooldown that was caused by the passive residual heat removal heat exchanger outlet flow control valve failing open. The trip was not complex, with all safety systems responding normally post-trip.</br>Operations responded and stabilized the plant. Decay heat is being removed by the passive residual heat removal heat exchanger. Units 1, 2, and 4 are not affected.</br>Due to the core makeup tank actuation, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(A). The reactor protection system actuation while critical is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Additionally, this event is reportable per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid containment isolation actuation and a valid passive residual heat removal heat exchanger actuation.</br>There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.</br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The failure of the control valve does not inhibit the residual heat removal system from functioning as it is passive. The reactor coolant system maximum allowable cooldown rate was exceeded (Technical Specification 3.4.3). The limit is 100 degrees F per hour above 350 degrees F. The maximum observed cooldown rate was 226 degrees F per hour. At time 0458 EDT, reactor coolant system temperature is 369.1 degrees F, reactor pressure is 900 psig. Currently, the plant is cooling down and proceeding toward placing shutdown cooling online.ng toward placing shutdown cooling online.
05:27:00, 17 September 2024 +
57,326 +
04:48:00, 17 September 2024 +
05:27:00, 17 September 2024 +
The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 0127 EDT on 9/17/2024, with Unit 3 in mode 1 at 100% power, the reactor automatically tripped due to the passive residual heat removal heat exchanger outlet flow control valve failing open. A manual safeguards actuation was initiated due to the lowering pressurizer water level resulting from the reactor coolant system cooldown that was caused by the passive residual heat removal heat exchanger outlet flow control valve failing open. The trip was not complex, with all safety systems responding normally post-trip.</br>Operations responded and stabilized the plant. Decay heat is being removed by the passive residual heat removal heat exchanger. Units 1, 2, and 4 are not affected.</br>Due to the core makeup tank actuation, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(A). The reactor protection system actuation while critical is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). Additionally, this event is reportable per 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in a valid containment isolation actuation and a valid passive residual heat removal heat exchanger actuation.</br>There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.</br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The failure of the control valve does not inhibit the residual heat removal system from functioning as it is passive. The reactor coolant system maximum allowable cooldown rate was exceeded (Technical Specification 3.4.3). The limit is 100 degrees F per hour above 350 degrees F. The maximum observed cooldown rate was 226 degrees F per hour. At time 0458 EDT, reactor coolant system temperature is 369.1 degrees F, reactor pressure is 900 psig. Currently, the plant is cooling down and proceeding toward placing shutdown cooling online.ng toward placing shutdown cooling online.
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