The following information was provided by the licensee via phone and email:
At 0051 EDT on June 3, 2024, with Unit 3 in Mode 3 at 0 percent power, an actuation of the emergency feedwater system (EFW) occurred as main steam pressure was being lowered as part of reactor coolant system (RCS) cooldown for a planned shutdown. The reason for the EFW auto-start was lowering levels in the 3A and 3B steam generators following loss of the operating main feedwater pump. The main feedwater pump automatically tripped when main steam pressure was lowered below the automatic feedwater isolation system (AFIS) actuation setpoint before AFIS channels were taken to bypass. The 3A and 3B motor driven emergency feedwater pumps automatically started as designed when the low steam generator level signal was received for the 3A and 3B steam generators.
This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the EFW system.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.