15 juin 2014
Suite à l’analyse de différentes procédures, ce dissipateur n’avait pas été pris en compte et des pompes avaient été ignorées. Cette ignorance faisait tomber la réserve de dissipation de chaleur de 30 jours à environ 4 jours. Des mesures pour sécuriser les pompes ont été immédiatement prises, ainsi que des révisions de procédures.
Type : PWR - Puissance : 3 586 MWth - Première divergence n° 1 : 05/1987 ; n° 2 : 03/1988
Available in english only.
Event Number : 50227 - Facility : BRAIDWOOD - State : IL -
Unit : [1] [2] - RX Type : [1] W-4-LP,[2] W-4-LP -
Event Date : 06/25/2014 - Event Time : 15:55
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(ii)(B) - UNANALYZED CONDITION
Unit SCRAM Code RX CRIT Initial PWR Initial RX Mode Current PWR Current RX Mode 1 N Y 100 Power Operation 100 Power Operation 2 N Y 100 Power Operation 100 Power Operation
Event Text
POTENTIAL LOSS OF ULTIMATE HEAT SINK CAPACITY DUE TO LOW LEVEL
"At approximately 1555 CDT on Wednesday, June 25, 2014, during a review of several station abnormal operating procedures for actions related to low ultimate heat sink (UHS) level, it was discovered that the procedures do not incorporate design assumptions for shutting down the non-essential service water (WS) pumps following a loss of cooling lake dike. The pumps that take suction from the UHS include the WS, circulating water (CW) and fire protection (FP) pumps. Based on current procedural guidance, the only pumps that are secured due to a low ultimate heat sink level are the circulating water (CW) pumps based on low net positive suction (NPSH)
"Failing to secure the non-essential pumps on a loss of cooling lake dike failure significantly reduces the 30 day design basis UHS volume to approximately 4 days.
"This event is being reported in accordance with 10CFR50.72(b)(3)(ii)(B) for ’any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety.’
"Immediate actions taken included issuance of an operations standing order providing direction to secure non-essential pumps on the failure of the cooling lake dike. Proposed corrective actions include procedure revisions.
"The licensee has notified the NRC Resident Inspector."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140626en.html#en50227