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Etats-Unis : Watts Bar : démarrage automatique de la pompe d’alimentation en eau auxiliaire




13 août 2016


Ce démarrage est lié au problème de niveau d’eau trop bas dans les générateurs de vapeur. Le niveau d’eau aurait été rétabli à son niveau normal mais le délais nécessaire à ce rétablissement n’est pas précisé.

Type : PWR - Puissance : 3 459 MWth - Première divergence : 01 / 01 / 1996 -

Available in english only


Event Number : 52177

Facility : WATTS BAR - State : TN

Unit : [2] RX Type : [2] W-4-LP

Event Date : 08/13/2016 - Event Time : 03:36 [EDT]

Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION

Initial PWR : 0 % Current PWR : 0 %

Event Text

AUTOMATIC START OF TURBINE DRIVEN AUXILIARY FEED WATER PUMP

"On August 13, 2016 at 0330 EDT, Watts Bar Nuclear Plant Unit 2 (WBN2) was being stabilized following a pre-planned reactor trip. Both motor driven auxiliary feed water pumps and the turbine driven auxiliary feed water pump (TDAFW pump) were in operation maintaining steam generator water level 6 - 50 percent in accordance with the Reactor Trip Response Procedure.

"At 0333 EDT the TDAFW pump was secured by procedure and steam generator water level lowered to the Low Low Alarm setpoint (17 percent). The trip time delay at 0 percent power is three (3) minutes. At 0336 EDT, the TDAFW pump automatically started with steam generator water levels less than the Low Low alarm setpoint (lowest level reached was 15 percent).

"Steam generator water level was restored to the normal shutdown control band (38 percent).

"Unit 1 remains in Mode 1 at 85 percent.

"Unit 2 is stable in Mode 3 with normal shutdown power alignment. The reactor coolant system is being cooled down to 400 degrees F for a planned maintenance period, with decay heat removal via the Main Condenser Steam dumps and the AFW system.

"This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A).

"TVA has notified the NRC Resident Inspector."

http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2016/20160815en.html