22 août 2013
Arrêt d’urgence du réacteur n° 1 qui était à 98 % de sa puissance suite à une baisse de niveau d’eau de refroidissement. L’arrêt se serait correctement effectué. Le cœur étant critique, les systèmes de protection du réacteur se sont enclenchés. La baisse de niveau est due à l’arrêt des trois pompes de refroidissement dont la cause d’arrêt est en cours de recherche.
1ère divergence juin 1972 - Type BWR-MARK 1 - P : 685 MW
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Event Number : 49296 Facility : PILGRIM - State : MA - Unit : [1] - RX Type : [1] GE-3
Event Date : 08/22/2013 - Event Time : 07:55 -
Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(iv)(A) - ECCS INJECTION 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Initial PWR 89 % - Current PWR 0 %
Event Text
REACTOR PROTECTION ACTUATION (SCRAM)
"On Thursday, August 22, 2013 at 0755 hours [EDT], with the reactor critical at approximately 98% core thermal power, and the mode switch in RUN, a manual reactor scram was inserted due to lowering reactor water level. The cause of the lowering reactor water level was due to the trip of all three Feedwater Pumps. The cause of the Feedwater Pump trip event is currently under investigation.
"Following the reactor scram, all control rods were verified to be fully inserted. All 4kV busses transferred to the Startup Transformer as designed. Following the scram the reactor water level lowered to +12 inches initiating the Primary Containment Isolation System (Group II, Reactor Building Isolation System (RBIS) ; and Group VI - Reactor Water Cleanup System) automatically as per design.
"Reactor water level lowered to -46 inches initiating Primary Containment Isolation System Group I - Main Steam Isolation Valves (MSIVs) ; Emergency Core Cooling Systems (ECCS) actuated which included automatic start and injection of the High Pressure Coolant Injection (HPCI) System and the Reactor Core Isolation Cooling (RCIC) System and an automatic start of the Emergency Diesel Generators as designed. Reactor water level was promptly restored to normal level.
"Currently a cooldown is in progress with reactor pressure is being maintained by the HPCI System operating in the pressure control mode and reactor water level is being maintained by the RCIC System. Reactor Water Clean-up System and normal reactor building ventilation have been restored. Off-site power is being supplied to the station by the Start-up Transformer (normal power supply for shutdown operations).
"This event had no impact on the health and/or safety of the public. The USNRC Senior Resident Inspector has been notified. This 4-hour notification is being made in accordance with 10 CFR 50.72 (b)(2)(iv)(A) and (B)."
The plant is transferring from decay heat removal to the torus to decay heat removal to the main condenser. Reactor pressure is 371 psig.
Initial indications are that a main feedwater power supply breaker tripped.
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