16 septembre 2016
Lors de ce démarrage, deux bus étaient alimentés par le transformateur d’arrêt alors qu’ils auraient du l’être par celui de démarrage... avec la perte de ces bus, le réacteur perdait des fonctions de sécurité essentielles. 36 minutes après la découverte de l’erreur, les lignes d’alimentation des bus ont été rétablies.
Type : PWR - Puissance : 2 817 MWth - première divergence : 08 / 1977 -
Available in english only
Event Number : 52247
Facility : DAVIS BESSE
State : OH - Unit : [1] - RX Type : [1] B&W-R-LP
Event Date : 09/16/2016 - Event Time : 16:57 [EDT]
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(A) - POT UNABLE TO SAFE SD 50.72(b)(3)(v)(B) - POT RHR INOP 50.72(b)(3)(v)(C) - POT UNCNTRL RAD REL 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 0 % Current PWR : 0 %
Event Text
ESSENTIAL BUSSES NOT ALIGNED TO POWER TRANSFORMERS DURING PLANT STARTUP
"At 1657 Eastern Daylight Time (EDT) the plant entered Mode 4 (from Mode 5), and subsequently, at 1710 EDT, it was discovered that 480V AC essential busses E1 and F1 were being supplied from the shutdown operations transformers. The essential busses E1 and F1 are required to be aligned to the power operations transformers in Mode 4 for operability in accordance with TS 3.8.9.
"With both E1 and F1 essential busses aligned to the shutdown operations transformers with the plant in Mode 4, both trains of the essential electrical power distribution system were inoperable, resulting in a loss of safety function. At 1733 EDT both E1 and F1 essential busses were aligned to the power operations transformers as required by TS 3.8.9.
"This issue is being reported as a loss of safety function of the essential electrical busses.
"The NRC Resident Inspector has been notified of the event."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2016/20160919en.html#en52247
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