Event Notification Report for December 04, 2023

U.S. Nuclear Regulatory Commission
Operations Center

12/01/2023 - 12/04/2023

Power Reactor
Event Number: 56877
Facility: South Texas
Region: 4     State: TX
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Mark Hamilton
HQ OPS Officer: Adam Koziol
Notification Date: 12/02/2023
Notification Time: 12:47 [ET]
Event Date: 12/02/2023
Event Time: 06:10 [CST]
Last Update Date: 12/02/2023
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
Taylor, Nick (R4DO)
Power Reactor Unit Info
Unit SCRAM Code RX Crit Initial PWR Initial RX Mode Current PWR Current RX Mode
2 N Y 100 Power Operation 100 Power Operation
Event Text

The following information was provided by the licensee via email:

"At 0610 CST on 12/2/2023, with Unit 2 in Mode 1 at 100 percent power, the South Texas Project switchyard south electrical bus was de-energized. Emergency diesel generator (EDG) '22' automatically started in response to the loss of offsite power on the train 'B' engineered safety feature (ESF) electrical bus.

"This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in the valid actuation of an emergency AC electrical power system (50.72(b)(3)(iv)(B)(8)).

"All required loads were successfully started. There was no impact on the health and safety of the public or plant personnel.

"The NRC Resident Inspector has been notified."

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

The initial loss of the south electrical bus, partial loss of off-site power, put the plant in a 24 hour limiting condition for operation (LCO) in accordance with (IAW) technical specification (TS) Power was restored to the train 'B' ESF bus via an alternate offsite power source and the EDG was returned to its automatic standby condition. Currently, the plant is in a 72 hour LCO IAW TS