26 octobre 2017
Ce système qui est prévu pour empêcher le confinement primaire de dépasser la pression de conception de 0,137 bars a été découvert en panne lors d’une surveillance mensuelle. Suite à ce problème sur deux voies du réacteur, celui-ci est entré en phase de limitation d’opération avec arrêt sous 72 heures.
Type : BWR Mark 3 - Puissance : 3 898 MWth - Première divergence : 8 / 1982 -
Available in english only
Event Number : 53038
Facility : GRAND GULF - State : MS
Unit : [1] - RX Type : [1] GE-6
Event Date : 10/26/2017 - Event Time : 14:45 [CDT]
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100 %
Event Text BOTH DIVISIONS OF DRYWELL VACUUM RELIEF DECLARED INOPERABLE
"At 1055 [CDT], drywell purge supply/initial vacuum relief 1E61F003B was declared INOPERABLE for Drywell Vacuum Relief System while performing a monthly surveillance. 1E61F003B is a Division II powered valve. Division 1 Emergency Diesel Generator is INOPERABLE due to a tagout. At 1455, under LCO 3.8.1.B.2 the station declared both divisions of Drywell Vacuum Relief INOPERABLE. GGNS [Grand Gulf Nuclear Station] identified that a loss of Safety Function occurred due to a loss of two 10-inch vacuum relief lines from the Drywell required by Technical Specification 3.6.5.6 and therefore could have prevented fulfillment of its safety function. That event is being reported under 10CFR50.72(b)(3)(v)(D), as any event or condition that, at the time of discovery, could have prevented the fulfillment of the safety function of structures or systems that are needed to mitigate the consequences of an accident. "
Both divisions inoperable has placed the plant in a 72-hr. LCO shutdown action statement.
The licensee has notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2017/20171027en.html