22 mai 2015
Ce démarrage a eu lieu suite à la perte de l’alimentation vitale de 1 600 volts. Le diesel a été arrêté par les opérateurs et l’alimentation rétablie par le 115 000 v des lignes extérieures via un transformateur de secours. La baisse de tension intempestive est survenue suite au branchement de matériel de mesure pour la réalisation de tests sur le diesel et sur la perte de puissance sur un circuit de test. La voie de secours en cours de maintenance était indisponible durant ce test et ne permettait pas d’assurer le refroidissement du cœur.
Type : BWR Mark 2 - Puissance : 3 486 MWth - Première divergence : 01/1984
Available in english only.
Event Number : 51086
Facility : COLUMBIA GENERATING STATION - 4 State : WA -
Unit : [2] - Type : [2] GE-5
Event Date : 05/22/2015 - Event Time : 00:14
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Initial PWR : 0 % - Current : 0 %
Event Text
EMERGENCY DIESEL GENERATOR START DUE TO ACTUATION OF UNDERVOLTAGE CIRCUITRY
"At 0014 PDT on 05/22/2015, Columbia experienced an unexpected momentary loss of SM-7, a Division 1 4.16 kV vital bus, resulting in a start of Emergency Diesel DG-1 . Additionally, under voltage circuitry prevented Standby Service Water pump 1A from starting to support DG-1 in response to the valid under voltage condition, and operators tripped the diesel at 0016 PDT. The SM-7 bus was reenergized by a 115 kV offsite source through backup transformer TR-B.
"The cause of this event was an inadvertent trip of under voltage circuitry while connecting test equipment in preparation for Diesel and Loss of Power logic testing. Division 1 was inoperable due to ongoing maintenance during the current refueling outage and was not being relied upon for decay heat removal or core circulation.
"Columbia is in Mode 5 with a coolant temperature of 96 degrees F, water level is at the normal refueling flooded level with fuel pool cooling gates removed. Division 2 is providing required electrical power and supporting components required for decay heat removal and inventory control. There was no impact to Shutdown Safety Assessment."
The NRC Resident Inspector has been notified.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150526en.html#en51086