13 décembre 2013
En cas d’accident, le système de filtration d’urgence de l’air de la salle de contrôle était incapable d’assurer sa fonction de maintien de cette salle en surpression par rapport aux bâtiments qui la jouxtent. L’instrumentation de mesure de pression des salles n’a pas été installé à Columbia ! Le 25 novembre, a été identifié le non respect des limites prescrites pour l’étanchéité entre les bâtiments. Le 13 décembre, la découverte d’un trou de passage de câbles entre la salle de commande et une salle adjacente constitue un viol supplémentaire de la règlementation, empêchant d’assurer les fonctions de sécurité en cas d’accident.
Type : BWR - Puissance : 3486 MWTh - Première divergence : 01/1984
Available in english only.
Event Number : 49631
Facility : COLUMBIA GENERATING STATION - State : WA
Unit : [2] - RX Type : [2] GE-5
Event Date : 11/25/2013 - Event Time : 15:00
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(D) - ACCIDENT MITIGATION
Initial PWR : 100 % Current PWR : 100 %
Event Text
BREACH SIZES EXCEEDED FOR CONTROL ROOM ENVELOPE
"On December 13, 2013 it was determined that a reportable condition has existed at Columbia Generating Station since 1500 hours [PST] on November 25, 2013.
"At 1500 hours on November 25, 2013, the Control Room Envelope (CRE) was declared inoperable based on the inability to ensure that the Control Room Emergency Filtration (CREF) System would be able to maintain a positive differential pressure with all areas surrounding the CRE boundary. Columbia does not have the installed instrumentation to directly monitor the differential pressure between the Main Control Room (MCR) and certain areas adjacent to the MCR. The pressure in the adjacent areas is controlled by placing conservative limits on allowed breach size for these adjacent areas.
"On November 25, 2013, it was identified that the combined breach size associated with several doors in these adjacent spaces resulted in exceeding the allowed limit. Based on exceeding the allowed breach size limit to the adjacent areas, the Control Room Envelope was declared inoperable, and Technical Specification Action Statement 3.7.3.B.1 was entered.
"An additional breach was discovered on 12/05/13 from a hole in ductwork passing through the cable spreading room, which is one of the adjacent areas to the CRE boundary, and that condition was added to the existing action statement 3.7.3.B.1. These are conditions that could have prevented fulfillment of a safety function of structures that are needed to mitigate the consequences of an accident and are reportable under 10 CFR 50.72(b)(3)(v)(D)."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2013/20131216en.html
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