Event Notification Report for June 04, 2024

STUCK SHUTTER

The following is a summary of information obtained from the licensee via phone:

The assistant radiation safety officer (ARSO) received a notification from their Tilden Mine site that a Ohmart Vega (model SH-F1B-0) containing 1 mCi of Cs-137 had a stuck open shutter. The ARSO is evaluating whether to contact Vega to schedule a technician to service the shutter or to amend their NRC license to allow them to service the shutter. The nuclear gauge is in a location inaccessible to personnel and there is no additional exposure risk to personnel or the public.

AUTOMATIC REACTOR TRIP

The following information was provided by the licensee via phone and email:

"Surry Unit 1 reactor automatically tripped at 1708 EDT on 6/2/24 due to a turbine trip [with the reactor operating at greater than 10 percent reactor power].

"The turbine control system is currently under investigation. Reactor coolant temperature is being maintained via main steam dumps with main feedwater supplying the steam generators.

"All systems operated as required. The trip was uncomplicated and all control rods fully inserted into the core. There was no emergency core cooling system (ECCS) or auxiliary feedwater system actuation. Offsite power remains available. There is no impact to Surry Unit 2.

"This notification is being made pursuant to 10 CFR 50.72(b)(2)(iv)(B) for 4-hour notification of reactor protection system activation. The NRC Resident Inspector has been notified.

"There were no radiation releases, personnel injuries, or contamination events due to this event."

AUTOMATIC ACTUATION OF EMERGENCY FEEDWATER SYSTEM

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."