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Etats-Unis : Fort Calhoun : Perte de refroidissement du générateur de vapeur A




5 juin 2015


Durant le rechargement combustible, une panne a été découverte lors des tests sur le circuit auxiliaire d’alimentation en eau d’un générateur de vapeur. Une soupape (HCV-1107A), chargée d’évacuer la chaleur vers le générateur de vapeur, a refusé de s’ouvrir. Le cœur n’était pas critique et sa température était de 268 °C.

Type : PWR - Puissance : 1 500 MWth - Première divergence : 08/1973

Available in english only.


Event Number : 51131

Facility : FORT CALHOUN - State : NE

Unit : [1] - RX Type : (1) CE

Event Date : 06/05/2015 - Event Time : 13:30

Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(3)(v)(B) - POT RHR INOP

Initial PWR : 0% - Current PWR : 0 % -

Event Text

LOSS OF DECAY HEAT REMOVAL TO THE ’A’ STEAM GENERATOR

The following information was provided via email and telephone.

"Fort Calhoun Station is currently completing a scheduled refueling outage. On June 5, 2015 at 1330 during performance of surveillance testing on the auxiliary feed water system, [Hydraulic Control Valve] HCV-1107A, Steam Generator RC-2A Auxiliary Feedwater Inlet Valve, did not open when given an open signal. HCV-1107A has been declared inoperable. HCV-1107A is required to open to meet the decay heat removal safety function for Steam Generator A. Fort Calhoun Station is in Mode 3 (Reactor Coolant System temperature is greater than 515 degrees Fahrenheit and not critical). With HCV-1107A inoperable and unable to feed the A steam generator both auxiliary feedwater trains are considered inoperable. HCV-1107A is inside the Containment Building.

"Fort Calhoun Station Technical Specifications 2.5(1)D. requires : With both AFW trains inoperable, then initiate actions to restore one AFW train to OPERABLE status immediately. Technical Specification (TS) 2.0.1 and all TS actions requiring MODE changes are suspended until one AFW train is restored to OPERABLE status.

"Fort Calhoun Station is evaluating the best approach to repairing HCV-1107A.

"The Resident Inspector has been notified"

* * * UPDATE PROVIDED BY CHARLIES SMITH TO RICHARD SMITH AT 2300 EDT ON 06/05/2015 * * *

"Fort Calhoun Station has determined plant cooldown required to perform repairs. Plant cooldown in progress."

The licensee will notify the NRC Resident Inspector.

Notified R4DO (Whitten)

http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150608en.html#en51131