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Etats-Unis : Browns Ferry : Circuit d’injection de liquide de refroidissement haute pression hors service




22 juillet 2015


C’est au cours du contrôle trimestriel de la vanne d’isolation de la ligne de vapeur que celle-ci n’a pas assuré sa fermeture dans les délais impartis. Ce problème a été déclaré au titre de l’indisponiblité d’un élément sans voie de contournement devant permettre d’assurer l’atténuation des conséquences de la survenue d’un accident.

Type : Fukushima 1 (BWR Mark1) - Puissance : 3 458 MWth - Première divergence : 08/1973

Available in english only.


Event Number : 51250

Facility : BROWNS FERRY - State : AL -

 Unit : [1] - RX Type : [1] GE-4

Event Date : 07/22/2015 - Event Time : 04:45

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

Initial PWR : 100 % - Current PWR : 100 % -

Event Text

HPCI DECLARED INOPERABLE

"During the performance of the Unit 1 quarterly surveillance 1-SR-3.6.1.3.5 (HPCI), HPCI [High Pressure Coolant Injection] System Motor Operated Valve Operability, the inboard steam isolation valve failed to close within the required time. The valve was subsequently declared inoperable and Technical Specification (TS) Limiting Condition for Operation (LCO) 3.6.1.3 (Primary Containment Isolation Valves (PCIVs)) was entered which required the HPCI steam line to be closed and de-activated. To comply with TS LCO 3.6.1.3 Condition A, the outboard steam isolation valve was closed and breaker opened. Due to the steam line being isolated, TS 3.5.1, ECCS Operating, Condition C was entered on July 22, 2015 at 0445 CDT as a result of the inoperable HPCI system. Troubleshooting and repair is in progress and during this inoperability, other systems are available to provide the required safety functions.

"This constitutes an unplanned HPCI system inoperability and requires an 8-hour ENS notification in accordance with 10 CFR 50.72(b)(3)(v)(D), due to the failure of a single train system affecting accident mitigation, and a 60-day written report in accordance with 10 CFR 50.73(a)(2)(v)(D).

"The NRC Resident Inspector has been notified."

http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150723en.html#en51250