31 octobre 2012
Au cours de la révision de la centrale de Browns Ferry par l’Association nationale de protection contre l’incendie, il a été découvert que, en cas d’incendie, il était potentiellement impossible d’assurer une alimentation électrique pour mettre les trois réacteurs en arrêt sûr.
Available in english only.
Des dommages, suite à un feu sur une baie d’alimentation en 480 V, sont susceptibles de poser des problèmes au niveau des sectionneurs de sécurité dont les fusibles de protection sont inadaptés. Les câbles eux-mêmes peuvent être détruits par le feu.
Des mesures compensatoires sont mises en place pour prendre en compte les remarques de l’Association nationale de protection contre l’incendie.
Facility : BROWNS FERRY - Region : AL - Unit : [1] [2] [3] - RX Type : [1] GE-4,[2] GE-4,[3] GE-4
Event Date : 10/31/2012 - Event Time : 12:53 [CDT]
Emergency Class : NON EMERGENCY
50.72(b)(3)(ii)(B) - UNANALYZED CONDITION 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
RX Mode 1 N N 0 Refueling 0 Refueling 2 N Y 100 Power Operation 100 Power Operation 3 N Y 100 Power Operation 100 Power Operation
Event Text
POTENTIALLY UNABLE TO PROVIDE POWER TO SAFE SHUTDOWN EQUIPMENT DURING APPENDIX R FIRE
"During BFNP [Browns Ferry Nuclear Plant] NFPA [National Fire Protection Association] 805 transition review, it was determined in the event of an Appendix R fire, the ability to provide power to equipment needed to achieve and maintain safe shutdown may be adversely impacted. In certain fire zones/areas, feeder breakers for the 480V Shutdown Boards are credited for backup control operation using the 43 emergency switches, which isolate the breaker controls from circuits going to the control bay, and allow for local operation of the breaker. Fire damage to Main Control Room 480V Shutdown Board transfer switch cables could cause the control circuit fuses for the credited breaker to clear prior to the use of the 43 emergency switch. In addition, cable fire damage in the same fire areas could also cause the normal and/or alternate feeder breakers to spuriously trip. These breakers do not have separate emergency fuses like other BFNP breakers equipped with backup controls. Therefore, Safe Shutdown Instruction (SSI) procedure steps to use 43 switches to perform local breaker operation to supply power to safe shutdown equipment may not work as written where this cable fire damage can occur.
"Compensatory actions in the form of fire watches to mitigate this condition are in place in accordance with the BFNP Fire Protection Report.
La boutique
Informez vous