18 juillet 2015
C’est lors de tests de surveillance que ces deux pompes ont été découvertes en panne. La perte de ces éléments de sécurité constituent une défaillance dans le système chargé d’atténuer la contamination radioactive en cas de survenue d’un accident.
Type Fukushima 1 (BWR Mark 1 ) - Puissance 2 419 MWth - Première divergence : 02/1974
Available in english only.
Event Number : 51240
Facility : COOPER - State : NE
Unit : [1] - RX Type : [1] GE-4
Event Date : 07/18/2015 - Event Time : 12:14
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(C) - POT UNCNTRL RAD REL 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100% - Current PWR : 100 % -
Event Text
STANDBY GAS TREATMENT SYSTEM DECLARED INOPERABLE DUE TO INOPERABLE SUMP PUMPS
"At 1214 CDT on 7/18/2015, during normal surveillance testing of Z sump, Z2 sump pump run time was found to exceed its upper Augmented IST limit, rendering it non-functional. Operators continued with the surveillance, opening the power supply breaker to Z1 sump pump, rendering it non-functional also. When this was identified, station personnel backed out of testing and restored power to Z1 sump pump. Z sump functions to limit condensation buildup in the common Standby Gas Treatment System (SGT) discharge line to support SGT operability. One sump pump is required to be functional to support SGT operability. With both Z sump pumps non-functional, operability of both trains of SGT is not assured. Loss of both trains of SGT constitutes a loss of safety function for control of rad release and accident mitigation per 10 CFR 50.72(b)(3)(v) functions (C) and (D).
"The breaker for Z1 sump pump was reclosed at 1225 CDT, restoring functionality to Z1 sump pump and operability to both trains of SGT. Both Z sump pumps were considered non-functional and unable to support SGT operability for a period of 11 minutes."
The licensee notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150720en.html#en51240