28 août 2014
Après avoir déclaré les deux voies des générateurs diesels d’urgence hors service le 21 novembre 2013, la NRC a retiré ce problème de la liste des incidents au motif que la voie 2 restait disponible malgré une visualisation défaillante.
Type : Fukushima 1 (BWR Mark I) - Puissance : 1 912 MWth - Première divergence : 03/1974 (soit 40 ans)
Available in english only.
Note : Cette offensive de déclassement de problèmes de la part de la NRC permettra de présenter des chiffres rassurants, mais ne changera rien au fond. En effet, en cas de survenue de problèmes graves, qui peut prédire la réaction du pilote du réacteur qui verra ses deux diesels d’urgence hors service ?
Event Number : 49566
Facility : DUANE ARNOLD - 3 State : IA -
Unit : [1] - RX Type : [1] GE-4 - Event Date : 11/21/2013 - Event Time : 02:29
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100 %
Event Text
DIESEL GENERATOR INOPERABILITY
"Following preplanned maintenance on the inoperable ’A’ Standby Diesel Generator (SBDG), the operability surveillance (STP-3.8.1-04A Slow Start from Normal Air) was in progress. While securing the ’A’ SBDG, the ’B’ SBDG control power failure annunciator was received.
"The ’B’ Standby Diesel Generator was declared inoperable and Technical Specification 3.8.1.B was entered for the ’B’ SBDG. Additionally, Technical Specification 3.8.1.D was entered for two Standby Diesel Generators inoperable. Technical Specification 3.8.1.D allows 2 hours to restore 1 SBDG to operable.
"At 0343 [CST], the ’A’ SBDG was restored to operable and Technical Specification 3.8.1.D was exited.
"This condition is reported under 50.72(b)(3)(v)(D), any event or condition 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.
"The NRC Resident Inspector was informed."
* * * RETRACTION FROM BOB MURRELL TO DONALD NORWOOD AT 1348 EDT ON 8/28/2014 * * *
"The purpose of this notification is to retract a previous report made on 11/21/2013 at 1038 EST (EN 49566). Notification of the event to the NRC was initially made as a result of declaring both trains of the Emergency Diesel Generator (EDG) System inoperable due to receiving the ’B’ EDG control power failure annunciator while the ’A’ EDG was inoperable for pre-planned maintenance.
"Subsequent to the initial report, NextEra Energy Duane Arnold (NextEra) has determined that the ’B’ EDG system was capable of performing its safety function and was fully operable, but degraded during the period that the ’A’ EDG was inoperable for pre-planned maintenance. The cause of the annunciator was from an open fuse in the control power circuit that affected the annunciator system logic and did not affect the actual EDG control logic.
"This event is not considered a Safety System Functional Failure and is not reportable to the NRC as a Licensee Event Report (LER) per 10 CFR 50.73.
"The NRC Senior Resident Inspector has been notified."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140829en.html#en49566
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