21 mai 2010
Les causes de l’arrêt de la turbine sont en cours de recherche. Le réacteur a été arrêté correctement, à une exception près : un moteur de vanne sur le circuit d’alimentation en eau n’a pas fonctionné, mais le débit d’eau aurait été suffisant pour assurer un refroidissement des générateurs de vapeur. Le cœur étant critique, les systèmes de protection du réacteur se sont enclenchés.
Type : PWR - Puissance thermique : 3 459 MWTh - Première divergence : 01/1996
Available in english only.
Event Number : 45944
Facility : WATTS BAR - State : TN - Unit : [1] - RX Type : [1] W-4-LP
Event Date : 05/21/2010 - 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
AUTOMATIC REACTOR TRIP ON TURBINE TRIP
"At 1937 Eastern Daylight Saving Time (EDT), Watts Bar Nuclear Power Plant Unit 1 experienced a reactor trip due to a turbine trip. This caused an automatic AFW Pump start from P-4 coincident with Lo Tave signal. The cause of the turbine trip has not yet been identified, and is under investigation.
"The plant is stable and is being maintained in Mode 3, at normal operating pressure and temperature, with steam generator and pressurizer levels normal.
"Plant systems responded to return the plant to a stable condition without complication, and all systems performed as expected with one exception :
"The ’B’ Motor Driven Auxiliary Feedwater Backpressure Control Valve failed closed, but the Steam Driven Auxiliary Feedwater Pump provided sufficient feedwater so that all Steam Generators were provided sufficient feedwater to maintain cooling and normal steam generator level.
"Plans for plant restart are pending awaiting the cause investigation.
"All control rods inserted into the core. Plant decay heat removal is through the steam dumps to the main condenser. Offsite power is available and lined up to plant system loads.
"Watts Bar [NRC] Resident Inspector has been notified of this event."