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Etats-Unis : Grand Gulf : groupes électrogènes d’urgence hors service




18 février 2018


Sur les deux diesels en panne, un était en maintenance et l’autre avait sa température d’eau qui dépassait les seuils limites autorisés. Le réacteur a continué de fonctionner à 97 % de sa puissance nominale durant 3 h 49 sans disposer diesel d’urgence de secours !

Type : BWR Mark3 - Puissance : 3 898 MWth - Première divergence : 08 1982 -

Available in english only


Event Number : 53227

Facility : GRAND GULF - State : MS

Unit : [1] - RX Type : [1] GE-6

Event Date : 02/18/2018 - Event Time : 00:06 [CST]

Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION

Initial PWR  : 97 % Current PWR  : 97 %

Event Text

EMERGENCY DIESEL GENERATORS INOPERABLE

"On February 18, 2018, Grand Gulf Nuclear Station experienced the concurrent inoperability of two Emergency Diesel Generators [DG]. This event is being reported as a late 8-hour non-emergency notification per 10 CFR 50.72(b)(3)(v)(D) as an ’Event or Condition that Could Have Prevented Fulfillment of a Safety Function (Accident Mitigation).’

"On February 14, 2018 at 0100 [CST], the Division 2 Diesel Generator was declared inoperable, and subsequently removed from service for maintenance. On February 18, 2018 at 0006 [CST], the Division 3 Diesel Generator Jacket Water temperature exceeded the trip setpoint and Division 3 Diesel Generator was declared inoperable. The Division 2 Diesel Generator was restored and declared operable on February 18, 2018 at 0355 [CST], and the Division 3 Diesel Generator was restored and declared operable on February 18, 2018 at 1240 [CST]. As a result, Technical Specification Condition 3.8.1.E was entered at 0006 [CST] on February 18, 2018 and exited at 0355 [CST] on February 18, 2018.

"Technical Specification Bases 3.8.1.E.1 states ’With two DGs inoperable, there is one remaining standby AC source. Thus, with an assumed loss of offsite electrical power, insufficient standby AC sources are available to power the minimum required ESF functions.’

"Offsite power was available throughout this event and there was no impact to the health and safety of the public or plant personnel.

"The NRC Resident Inspector has been notified."

https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2018/20180226en.html