Nuclear Event – Automatic Reactor Trip: Watts Bar Nuclear Plant, Unit 2
North America – USA | State of Tennessee, Rhea County, Spring City, Watts Bar Nuclear Plant
Location: 35°36’10.0″N 84°47’22.0″W
Site Operational Age: ~31 years
Event: RPS ACTUATION – CRITICAL/AUTOMATIC REACTOR TRIP
Nuclear Event in USA on Monday, 20 June, 2016 at 15:40 [EDT].
AUTOMATIC REACTOR TRIP
“On June 20, 2016 at 1540 EDT, Watts Bar Nuclear Plant Unit 2 reactor tripped due to [reaching the] automatic Lo-Lo steam generator trip [setpoint] on [the] #4 steam generator. Concurrent with the reactor trip the Auxiliary Feedwater system actuated as designed.
“All control and shutdown rods fully inserted. All safety systems responded as designed. The unit is currently stable in Mode 3, with decay heat removal via Auxiliary Feedwater and main steam dump systems. The station is in a normal shutdown electrical alignment.
“The cause is currently under investigation.
“This is being reported under 10 CFR 50.72(b)(3)(iv)(A) and 10 CFR 50.72 (b)(2)(iv)(B).
“The NRC Senior Resident has been notified.”
There was no effect on Unit 1.
Nuclear Event in USA on Sunday, 05 June, 2016 at 12:27 [EDT]. REACTOR TRIP AND ECCS ACTUATION CAUSED BY TURBINE GOVERNOR VALVE FAILURE
Nuclear Event in USA on Tuesday, 22 March, 2016 at 11:31 [EDT]. WATTS BAR AUTOMATIC REACTOR TRIP UNIT 1 [due to the actuation of the Over Temperature Delta Temperature bistables.]
Nuclear Event in USA on Thursday, 17 March, 2016 at 01:15 [EDT]. LOSS OF EMERGENCY AND AUXILIARY GAS TREATMENT SYSTEMS – UNIT 1
Nuclear Event in USA on Wednesday, 09 March, 2016 at 03:42 [EST]. UNUSUAL EVENT DECLARED DUE TO A FIRE GREATER THAN 15 MINUTES – UNIT 2