13 juillet 2014
Le réacteur n° 1 a été arrêté manuellement suite à l’isolement automatique de tous les réchauffeurs. Les premiers constats montreraient que le switch défaillant d’un réchauffeur a conduit au déclenchement des pompes du réservoir et lorsque le niveau haut a été atteint, le système de refroidissement a été isolé.
Type : PWR - Puissance : 3 459 MWth - Première divergence : 01/1996
Available in english only.
Event Number : 50278
Facility : WATTS BAR - State : TN - Unit : [1] - RX Type : [1] W-4-LP
Event Date : 07/13/2014 - Event Time : 19:37
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Initial PWR : 100 % - Current PWR : 0 %
Event Text
MANUAL REACTOR TRIP DUE TO AUTOMATIC FEEDWATER HEATER ISOLATION
"On July 13, 2014 at 1937 [EDT], Watts Bar Nuclear Plant Unit 1 reactor was manually tripped due to automatic isolation of all low pressure feedwater heaters. Concurrent with the reactor trip the Auxiliary Feedwater system actuated as designed.
"All Control and Shutdown rods fully inserted. All safety systems responded as designed. The unit is currently stable in Mode 3, with decay heat removal via Auxiliary Feedwater, steam dumps and the main condenser. The station is in a normal shutdown electrical alignment.
"The cause is currently under investigation.
"This is being reported under 10CFR 50.72(b)(3)(iv)(A) and 10CFR 50.72 (b)(2)(iv)(B).
"The NRC Senior Resident [Inspector] has been notified."
Initial indications are that a level switch failed on the #7 heater drain tank which caused the heater drain tank pumps to trip. When the high level tank setpoint was reached, the feedwater system isolated.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20140714en.html
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