26 juillet 2014
Parmi ces systèmes activés intempestivement, on note diverses fermetures comme : une vanne de confinement du refroidissement du réacteur, une vanne du retour de refroidissement de la piscine et de son système de confinement, un robinet isolant l’eau de refroidissement du réacteur, une vanne du circuit de mesure, etc. Toutes ces opérations ont été effectuées sans justification de la situation réelle du réacteur. Un condensateur défectueux a été à l’origine du problème.
Type : BWR Mark III - Puissance : 3 758 MWth - Première divergence : 06/1986
Available in english only.
Event Number : 50450
Facility : PERRY - 3 State : OH -
Unit : [1] - RX Type : [1] GE-6 -
Event Date : 07/26/2014 - Event Time : 13:13
Emergency Class : NON EMERGENCY 10 CFR Section : 50.73(a)(1) - INVALID SPECIF SYSTEM ACTUATION
Initial PWR : 100 %
Current PWR : 100 %
Event Text
ELECTRICAL TRANSIENT CAUSES AN INVALID SYSTEM ACTUATION
"At 1313 [EDT] on 7/26/14, the plant experienced an electrical transient on bus EK-1-B1 (safety-related 120 volt AC distribution panel) that resulted in partial Balance of Plant Division 2 isolation signals and alarms received in the Control Room.
"The following component actuations occurred : valve 1P50F140 closed, resulting in a trip of Containment Vessel Chilled Water C ; valve 1G41F140 closed, isolating the Fuel Pool Cooling and Clean-up return from the containment building upper pools ; valve 1B33F019 closed, isolating Reactor Water sampling ; valve 1D17F071B closed, isolating the Drywell Atmosphere Radiation Monitor ; valve 1D17F081B closed, isolating the Containment Atmosphere Radiation Monitor ; valves 1G61-F030, 1G61-F150, 1G61-F075, and 1G61-F165 closed, isolating the Containment and Drywell Floor and Equipment drain sumps ; valve 1G50-F272 closed isolating the Reactor Water Cleanup Backwash Receiving Tank : 1M25F020B, Control Room HVAC Inboard supply damper, closed and Division 2 indicated an auto initiation (M25-S12, Auto Initiate Active amber light was on).
"This event is considered an invalid system actuation reportable under 10 CFR 50.73(a)(2)(iv)(A).
"The isolation was not initiated in response to actual plant conditions or parameters, and was not a manual initiation. Therefore, this notification is provided via a 60 day optional phone call in accordance with 10 CFR 50.73(a)(1) instead of submitting a written Licensee Event Report.
"The event meets reporting criteria specified in 10 CFR 50.73(a)(2)(iv)(B)(2) as a general containment isolation valve signal affecting containment isolation valves in more than one system. All affected systems functioned as expected in response to the electrical transient on bus EK-1-B1 that resulted in the partial Balance of Plant Division 2 isolation signals. The valves were reopened in accordance with plant procedures. The failure mechanism that caused the electrical transient was a failed capacitor in regulating transformer EFB1B2. The capacitor was replaced and tested with satisfactory results.
"The NRC Resident Inspector has been notified."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140915en.html#en50450
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