31 octobre 2012
Un problème sur le séquenceur du réacteur n° 1 a entraîné le démarage de la turbine d’alimentation en eau ainsi que le démarrage du groupe électrogène. La puissance du réacteur a baissé de 3 % avec une baisse de charge de 50 MW.
Available in english only.
Le séquenceur est toujours en cours de restauration. Un défaut a été trouvé sur son alimentation en 15 v et les investigations continuent pour déterminer si d’autres éléments ont participé à ce problème.
Facility : COMANCHE PEAK - Region : TX - Unit : [1]
Event Date : 10/31/2012 - Event Time : 06:15
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION Person (Organization) : RICK DEESE (R4DO)
1 N Y 100 Power Operation 97 Power Operation
Event Text
SEQUENCER FAULT RESULTING IN SYSTEM ACTUATIONS
"On October 31, 2012 at 0615 hours CDT, Unit 1 Train ’B’ Safety Injection/Blackout Sequencer faulted resulting in a start of the Turbine Driven Auxiliary Feed Water (TDAFW) Pump and Train ’B’ Emergency Diesel Generator (EDG). Reactor power was reduced to 97% rated thermal power (RTP) by an immediate load reduction of 50 MWe due to the resulting cooler Auxiliary Feed Water being injected into the Steam Generators ; reactor power did not exceed 100% RTP. Train ’A’ equipment was not affected by the event.
"The TDAFW Pump was secured at 0628 hours by closing the Train ’B’ steam supply valve from the main control board and the steam supply valve was declared operable at 0916 hours when the hand switch was returned to ’Auto’ and the control switch lineup surveillance was completed. The Train ’B’ EDG was loaded to 100% capacity in accordance with the operating procedure and secured at 1032 hours. The EDG is available but remains inoperable until the Sequencer is declared operable.
"Efforts continue to restore the Sequencer at this time. A faulted 15 Volt power supply was identified and further investigation/calibration will determine if other conditions contributed to the fault. A final surveillance test will determine Sequencer operability. The most limiting Shutdown Technical Specification action statement is 24 hours in accordance with Safety Injection Sequencer TS 3.8.1 F. Current projections for Sequencer operability, and thus Train ’B’ EDG operability, are 1800 hours.
"This action appears to be an invalid actuation. However, this will be confirmed after a cause analysis and an update to this event will be provided at that time."
The licensee has notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2012/20121101en.html
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