24 juillet 2015
Le système de refroidissement auxiliaire a pris le relais et l’arrêt se serait passé sans problème. L’origine du problème est en cours de recherche.
Type : PWR - Puissance : 3 455 MWth - Première divergence : 07/1980
Available in english only.
Event Number : 51259
Facility : SEQUOYAH - State : TN
Unit :  - RX Type :  W-4-LP
Event Date : 07/24/2015 - Event Time : 13:51
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
Initial PWR : 100 % - Current PWR : 0 %
AUTOMATIC REACTOR TRIP DUE TO TURBINE TRIP ON MAIN GENERATOR LOCKOUT
"At 1351 EDT on 7/24/2015, Sequoyah Unit 1 reactor/turbine automatically tripped.
"Following the reactor trip, all safety-related equipment operated as designed. Auxiliary Feedwater automatically initiated as expected from the Feedwater Isolation Signal.
"Unit 1 is currently being maintained in Mode 3 at NOT/NOP, approximately 548 F and 2235 psig, with auxiliary feedwater supplying the steam generators and decay heat removal via the condenser steam dumps. The immediate cause of the trip was an electrically-induced turbine trip. There was no associated work in progress related to this and all systems were normally aligned.
"There is no indication of any primary/secondary leakage. All rods fully inserted on the reactor trip and remain inserted. The electrical alignment is normal with shutdown power supplied from off-site power. The 2B-B Emergency Diesel Generator is currently in service for the performance of an unrelated surveillance. There is no operational impact to Unit 2. Unit 2 continues to operate in Mode 1 at 100%.
"There was no impact on public health and safety. Post-trip investigation is in progress and planned restart timeline has not yet been determined.
"The licensee notified the NRC Resident Inspector."