The fan trip did not involve a condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident under 10 CFR 50.72(b)(3)(v)(D). HPCI remained operable and there was no loss of safety function. "No other concerns were noted during the event. Based on the initial conditions at the time of the indication loss, specifically HPCI room and suppression pool temperature, it was determined that the resulting worst case post-accident room temperature was sufficiently low enough to provide margin to HPCI operability without the room cooler in service for the required mission time. "Following the initial EN, further analysis of the condition was performed utilizing a previously performed gothic analysis model (to perform HPCI room heat-up calculations) which bounded this condition. At 0429 EDT on June 14, 2023, the vibration switch was replaced, the MDCT fan "D" was tested satisfactory for operability, and the UHS, emergency diesel generator 13/14, and MDCT were declared operable. "The cause of the fan trip was a failed vibration switch. "The purpose of this notification is to retract a previous event notification (EN) 56570 reported on June 13, 2023, at 0602 EDT. * * * RETRACTION AT 1540 EDT ON FROM WHITNEY HEMINGWAY TO BILL GOTT * * * "The NRC Senior Resident Inspector has been notified." This report is being made pursuant to 10 CFR 50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. The cause of MDCT Fan `D' trip is currently unknown with trouble shooting being developed for remediation of the condition. An unplanned HPCI inoperability occurred based on a loss of the HPCI room cooler. The EECW system cools various safety related components, including the High-Pressure Coolant Injection (HPCI) system room cooler. The UHS is required to support operability of the division 2 Emergency Equipment Cooling Water (EECW) system. The MDCT fans are required to support operability of the Ultimate Heat Sink (UHS). "At 2333 EDT on June 12, 2023, the division 2 Mechanical Draft Cooling Tower (MDCT) Fan `D' was declared inoperable due to a trip of the fan while running in high speed. The following information was provided by the licensee via email: EN Revision Text: ACCIDENT MITIGATION - HIGH PRESSURE COOLANT INJECTION DECLARED INOPERABLE
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