11 mai 2018
La centrale nucléaire de Grand Gulf préparait un test de surveillance d’un générateur diesel. Une erreur d’ouverture de fusible a entrainé la coupure d’une arrivée d’alimentation électrique, qui a elle même entrainé le démarrage du groupe diesel de secours d’urgence. Suite à cette manœuvre, le circuit de traitement des gaz a été perdu et démarré manuellement selon la procédure. Le groupe diesel de secours d’urgence a été arrêté manuellement depuis la salle de commande car la voie d’alimentation en eau qu’il alimentait était indisponible. La voie B qui assurait le retrait de la chaleur résiduelle du cœur - en mode de refroidissement à l’arrêt.- a été contrôlée opérationnelle.
Type : BWR Mark3 - Puissance : 3 898 MWth - Première divergence : 08 / 1982 -
Available in english only
Event Number : 53399
Facility : GRAND GULF - State : MS Unit : [1] - RX Type : [1] GE-6
Event Date : 5 / 11 / 2018 Event Time : [CDT] : 23 h 27
Unit SCRAM Code RX Crit Initial PWR Initial RX Mode Current PWR Current RX Mode 1 N N 0 Refueling 0 Refueling
Event Text
INADVERTENT ACTUATION OF THE EMERGENCY DIESEL GENERATOR
"On 5/11/2018, at 2327 hours CDT, with the plant in Mode 5, Grand Gulf Nuclear Station was making preparations for surveillance test 06-OP-1P75-R-0003, Standby Diesel Generator 1 Functional Test. The Grand Gulf Nuclear Station experienced an auto-start of the Division 1 [Emergency] Diesel Generator [EDG] when the 15AA Bus Potential Transformer (PT) fuse drawer was racked out instead of the line PT fuse drawer for Bus 15AA feeder breaker 152-1514. This resulted in the 15AA Incoming Feeder Breaker 152-1511 from Engineered Safety Features Transformer 12 opening, de-energizing the 15AA Bus. The Division 1 EDG started and energized Bus 15AA. The Division 1 LSS SYSTEM FAIL annunciator was received and Standby Service Water A failed to start due to the 15AA Bus PT fuse drawer being racked out. Standby Gas Treatment Train B was manually initiated per the Loss Of AC Power Off Normal Emergency Procedure. Station equipment operated as expected based on the PT fuse drawer that was racked out.
"The Division 1 EDG was manually tripped from the Control Room because cooling from the Standby Service Water A was not available.
"RHR [residual heat removal] B was in Shutdown Cooling [mode] and was verified not affected"
The licensee has notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180514en.html