24 juin 2016
C’est la tombée d’un disjoncteur qui est à l’origine des problèmes parmi lesquels on peut noter :
la perte de ventilation ainsi que la surpression de l’enceinte de confinement du bâtiment réacteur,
la perte d’une voie de recirculation qui a entrainée la tombée de 50 % de la puissance du réacteur et la montée en température de l’autre voie.
Un arrêt à froid est en cours suite à la perte du système de refroidissement du bâtiment réacteur (RBCLCS) ainsi que du refroidissement de la piscine combustible.
Type : Fukushima 1 (BWR Mark 1) - Puissance : 2 536 MWth - Première divergence 11 / 1974
Available in English only
Event Number : 52042
Facility : FITZPATRICK
State : NY - Unit :  - RX Type :  GE-4 -
Event Date : 06/24/2016 - Event Time : 12:15
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 %
MANUAL REACTOR SCRAM DUE TO REACTOR RECIRCULATION PUMPS DEGRADATION
"At 1215 [EDT] on 6/24/2016, James A. FitzPatrick (JAF) was at 100% power when Breaker 710340 tripped and power was lost to L-gears L13, L23, L33, and L43. These provide non-vital power to Reactor Building Ventilation (RBV), portions of Reactor Building Closed Loop Cooling (RBCLC), and ’A’ Recirculation pump lube oil systems. Off-site AC power remains available to vital systems and Emergency Diesel Generators (EDG) are available.
"Due to the loss of RBV, Secondary Containment differential pressure increased. At 1215 [EDT], Secondary Containment differential pressure exceeded the Technical Specifications (TS) Surveillance Requirement SR-188.8.131.52.1 of greater than or equal to 0.25 inches of vacuum water gauge. The Standby Gas Treatment (SBGT) system was manually initiated and Secondary Containment differential pressure was restored by 1219 [EDT].
"The ’A’ Recirculation pump tripped at 1215 [EDT] and reactor power decreased to approximately 50%. ’B’ Recirculation pump temperature began to rise due to the degraded RBCLC system. At 1236 [EDT], a manual scram was initiated. Reactor Pressure Vessel (RPV) water level shrink during the scram resulted in a successful Group 2 isolation. All control rods have been inserted. The RPV water level is being maintained with the Feedwater System and pressure is being maintained by main steam line bypass valves. A cooldown is in progress and JAF will proceed to cold shutdown (Mode 4). Due to complete loss of RBCLC system, the Spent Fuel Pool (SFP) cooling capability is degraded but the Decay Heat Removal system remains available. SFP temperature is slowly rising and it is being monitored. The time [duration] to 200 degrees is approximately 117 hours.
"The initiation of reactor protection systems (RPS) due to the manual scram at critical power is reportable per 10 CFR 50.72(b)(2)(iv)(B) and 10 CFR 50.72(b)(3)(iv)(A). The general containment Group 2 isolations are reportable per 10 CFR 50.72(b)(3)(iv)(A). In addition, the temporary differential pressure change in Secondary Containment is reportable per 10 CFR 50.72(b)(3)(v)(C), as an event that could have prevented fulfillment of a safety function."