2 février 2014
Durant un orage, la foudre s’est abattue sur une des phases d’alimentation électrique du réacteur. Le système de protection a arrêté le réacteur suite à l’enclenchement du relais différentiel sur le 2,5 kV. Les trois pompes auxiliaires ont été enclenchées. Le cœur étant critique, les systèmes de protection du réacteur se sont enclenchés. Les opérations d’arrêt se seraient effectuées correctement.
Type : PWR - Puissance thermique : 3 411 MWTh - Première divergence : 08/1985
Available in english only.
Event Number : 49786
Facility : DIABLO CANYON - 4 State : CA - Unit : [2] - RX Type : [1] W-4-LP,[2] W-4-LP -
Event Date : 02/02/2014 - Event Time : 11:29
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(2)(xi) - OFFSITE NOTIFICATION 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Initial PWR : 100 % Current PWR : 0 %
Event Text
UNIT 2 AUTOMATIC REACTOR TRIP
"On February 2, 2014, at 11:29 PST, Diablo Canyon Power Plant Unit 2 500kV line differential relay actuated. This action tripped the turbine and opened the generator output breakers to isolate the generator. With the turbine tripped and Unit 2 operating above the P-9 50% power permissive, a reactor trip was initiated from the reactor protection system. All systems operated as designed with no problems observed. All three Unit 2 Auxiliary Feedwater pumps started, the Containment Fan Cooling units started and ran in slow speed, and the standby Auxiliary Saltwater train started, all as expected.
"Unit 2 is stable at normal operating temperature and pressure. All power transferred to the plant startup source without incident. Condenser vacuum was maintained.
"The preliminary cause of the differential relay actuation was a flashover of Phase B 500 kV to ground across the Phase B lightning arrestor during a rainstorm.
"Decay heat is being removed by steam dumps to the condenser. No relief valves lifted during the transient. The steam generators are being supplied by the auxiliary feedwater pumps. There were no injuries to personnel. Unit 1 was not affected.
"NRC Senior Resident Inspector and Region Branch Chief have been informed of this event.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140203en.html#en49786