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Etats-Unis : Surry : démarrage automatique du groupe électrique diesel suite à la déconnection intempestive de fusibles




17 janvier 2018


Cette ouverture par inadvertance de support fusibles s’est produite sur un circuit d’alimentation d’un bus d’urgence du réacteur n°1 qui était à 100 % de sa puissance. Le bus d’urgence a été réalimenté par le groupe diesel de secours qui a démarré automatiquement suite au problème. Après reconnection des fusibles, il y a eu réalimentation du bus par les sources extérieures.

 Type : PWR - Puissance : 2 857 MWth - Première divergence : 1 / 07 / 1972 -

Available in english only


Event Number : 53170

Facility : SURRY - State : VA

Unit : [1] - RX Type : [1] W-3-LP

Event Date : 01/17/2018 - Event Time : 09:52 [EST]

Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION

Initial PWR  : 100 % Current PWR  : 100 %

Event Text

AUTO-START OF EMERGENCY DIESEL GENERATOR DUE TO TRANSFORMER FUSES BEING DISCONNECTED

"At 0952 EST on 01/17/2018 with Unit 1 and Unit 2 operating at 100 percent, the normal supply breaker to the Unit 1J Emergency Bus tripped open due to an under-voltage condition when the potential transformer fuses were inadvertently disconnected. This resulted in a loss of power to the Unit 1J Emergency Bus from its normal off-site power supply. Number 3 Emergency Diesel Generator automatically started on an under-voltage signal and loaded onto the Unit 1J Emergency Bus, as designed.

"All equipment performed as expected during the event and there were no unexplained occurrences. Maintenance has verified the fuses have been reconnected and at 1221 EST, off-site power was restored to Unit 1J Emergency Bus. At 1254 EST Number 3 Emergency Diesel Generator was secured in accordance with Station Operating procedures.

"All Electrical distribution systems have been restored to a normal alignment.

"There were no radiation releases due to this event, nor were there any personnel injuries or contamination events.

"This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) due to the auto start of Number 3 Emergency Diesel Generator."

The licensee notified the NRC Resident Inspector.

https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180118en.html