23 avril 2015
Suite à l’indisponibilité d’un bus électrique, l’injection de liquide de refroidissement basse pression était indisponible. Il restait cependant disponible dans la configuration planifiée au moment de la panne. Le circuit de refroidissement du cœur a également été rendu indisponible par la perte de ce bus, mais la voie B est restée disponible. Cette défaillance aurait été rapidement résolue.
Type : Fukushima I (BWR Mark I ) - Puissance : 1 912 MWTh - Première divergence : 03/1974
Available in english only.
Event Number : 51006
Facility : DUANE ARNOLD - State : IA - Unit : [1] - RX Type : [1] GE-4
Event Date : 04/23/2015 Event Time : 10:50
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100 %
Event Text
SAFETY SYSTEMS DECLARED INOPERABLE DUE TO EQUIPMENT MALFUNCTION
"At 1050 [CDT] on 4/23/2015, an equipment malfunction resulted in DAEC [Duane Arnold Energy Center] declaring the Division 1 Essential Electrical Bus inoperable. The LPCI [ Low Pressure Coolant Injection] system was inoperable but available as part of a planned evolution at the time of the malfunction. Declaring the Essential Electrical Bus inoperable caused the ’A’ Core Spray System to be considered inoperable. LPCI and ’A’ Core Spray being inoperable simultaneously constituted a loss of safety function. The ’B’ Core Spray system remained operable and available. The equipment malfunction was resolved promptly, allowing the Division 1 Essential Electrical Bus to be returned to an operable status.
"The notification is being made pursuant to 10 CFR 50.72(b)(3)(v)(D).
"The [NRC] Resident Inspector has been notified."
The licensee entered and exited TS LCO 3.5.1 condition B.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150424en.html
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