14 octobre 2014
Cet arrêt a été engagé quand le transformateur alimentant le refroidissement des pompes du réacteur a été perdu. Les opérateurs ont enclenché toutes les pompes pour assurer le refroidissement du réacteur et l’injection d’eau de refroidissement se serait effectuée correctement. De violents orages sévissaient sur le site au moment de la perte du transformateur. Les diesels de secours d’urgence électrique étaient indisponibles suite à leur maintenance. C’est le réseau électrique extérieur qui a continué à alimenter le site. L’arrêt se serait effectué correctement avec l’insertion des barres de contrôle.
Type : PWR - Puissance : 2 275 MWth - Première divergence : 05/1981
Available in english only.
Event Number : 50533 - Facility : FARLEY - State : AL -
Unit : [2] - RX Type : [2] W-3-LP
Event Date : 10/14/2014 Event Time : 03:41 [CDT]
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 : 83 % Current PWR : 0 %
Event Text
MANUAL REACTOR TRIP DUE TO LOSS OF A START-UP TRANSFORMER
"This notification is being made as required by 10 CFR 50.72(b)(2)(iv)(B) due to a Farley Nuclear Plant Unit 2 manual reactor trip. The trip was initiated when the in service train of CCW cooling to the Reactor Coolant Pumps was lost due to a loss of the 2B Start Up Transformer (SUT). The control room team manually tripped the reactor then tripped all three reactor coolant pumps as required by station procedure. There was a line of severe thunderstorms with lightning passing through the plant site at the time of loss of the 2B Start Up Transformer. The 2B emergency diesel generator was out of service for maintenance therefore there was a loss of the ’B’ train emergency power 4160V electrical bus (’B’ train LOSP [Loss of Offsite Power]). ’A’ train emergency power remained energized from offsite sources. The plant is stable at normal operating pressure and temperature. At 0433 [CDT], 2B Reactor Coolant Pump was re-started when support conditions were re-established. Heat sink is adequate using the 2A Motor Driven Auxiliary Feedwater Pump.
"Unit 2 ’B’ train power was restored by starting the 2C emergency diesel generator at 0523 [CDT]. This restored power to the Digital Rod Position Indication system, and control rod K-8 in control bank ’C’ indicated full out, and all other control rods fully inserted. An emergency boration is in progress to compensate for the stuck rod.
"Additionally, the reactor trip resulted in a valid actuation of the Aux Feedwater system which is an eight hour non-emergency report per 10 CFR 50.72(b)(3)(iv)(A)."
During the transient, one primary PORV momentarily opened, then reseated. Decay heat is being directed to the atmospheric relief valves with no indicated primary to secondary leakage. There was no impact on Unit 1.
The licensee notified the NRC Resident Inspector.
* * * UPDATE AT 2125 EDT ON 10/15/2014 FROM BLAKE MITCHELL TO MARK ABRAMOVITZ * * *
"Digital rod position indication troubleshooting was conducted on 10/14/2014 and confirmed all control rods, including control rod K-8, fully inserted following the reactor trip."
The licensee notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2014/20141016en.html#en50533
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