Event Notification Report for March 18, 2021

U.S. Nuclear Regulatory Commission
Operations Center

03/17/2021 - 03/18/2021

Power Reactor
Event Number: 55143
Facility: Watts Bar
Region: 2     State: TN
Unit: [2] [] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Robert Collins
HQ OPS Officer: Thomas Kendzia
Notification Date: 03/17/2021
Notification Time: 12:59 [ET]
Event Date: 03/17/2021
Event Time: 10:04 [EST]
Last Update Date: 03/17/2021
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(2)(iv)(B) - RPS Actuation - Critical
50.72(b)(3)(iv)(A) - Valid Specif Sys Actuation
Person (Organization):
Power Reactor Unit Info
Unit SCRAM Code RX Crit Initial PWR Initial RX Mode Current PWR Current RX Mode
2 A/R Y 90 Power Operation 0 Hot Standby
Event Text

"At 1004 EDT on March 17, 2021, with Unit 2 in Mode 1 at 90 percent power, the reactor automatically tripped due to a main turbine trip. The trip was not complex, with all systems responding normally post-trip.

"Operations responded and stabilized the plant. Decay heat is being removed by the Auxiliary Feedwater and Steam Dump Systems. Unit 1 is not affected.

"Due to the Reactor Protection System actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). The expected actuation of the Auxiliary Feedwater System (an engineered safety feature) is being reported as an eight hour report under 10 CFR 50.72 (b)(3)(iv)(A).

"There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified."

All controls rods fully inserted and the electrical system is in normal shutdown alignment. The cause of the turbine trip is being investigated.

Page Last Reviewed/Updated Thursday, March 18, 2021