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At 0634 EDT on August 11, 2021 (high pressure coolant injection) HPCI was declared inoperable due to a pump flow controller problem. The cause of the controller problem is unknown at this time and is under investigation. (Reactor core isolation cooling) RCIC was verified operable per Tech Spec 3.5.1 E.1. This report is being made pursuant to 10CFR50.72(b)(3)(v)(D) based on an unplanned HPCI inoperability. There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.

• * * RETRACTION FROM WHITNEY HEMMINGWAY TO KAREN COTTON ON 10/6/2021 AT 1036 EDT * * *

The purpose of this notification is to retract a previous report made on August 11, 2021 (EN 55403). At 0634 EDT on August 11, 2021, an unplanned inoperability of the High Pressure Coolant Injection system (HPCI) was reported pursuant to 10 CFR 50.72(b)(3)(v)(D) by EN 55403. HPCI was declared inoperable due to receipt of an alarm associated with the pump flow controller. The HPCI system operating procedure states that HPCI should be declared inoperable when this alarm is received. The cause of the alarm, a loose transmitter connection, was identified and corrected. Following clearance of the alarm, HPCI was declared operable at approximately 1930 EDT on August 11, 2021. This alarm indicated a fault in the signal from the transmitter to the HPCI flow controller; in this case, the HPCI flow controller would have continuously called for maximum HPCI flow. The controller is configured with a high limiter to prevent an overspeed trip. An engineering evaluation of the event identified that HPCI was capable of performing its required safety functions while this alarm was present. The condition was that the HPCI flow controller would have continuously called for maximum HPCI flow upon HPCI initiation, however operators would be able to manually control HPCI flow upon HPCI initiation. Additionally HPCI would have run until Reactor Pressure Vessel (RPV) level reached Level 8 where it would trip until RPV level decreased to Level 2 then automatically restart. The licensee notified the NRC Resident Inspector. Notified R3DO (Peterson).