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Etats-Unis : Watts-Bar : durant un test planifié d’injection de secours, déclenchement intempestif du système de refroidissement d’urgence du coeur




26 novembre 2017


L’injection intempestive de liquide boré a été stoppée 7 minutes après son démarrage. Tous les autres systèmes ont répondu correctement. Les niveaux et pression du pressuriseur ont retrouvé leurs valeurs normales.

 Type : PWR - Puissance : 3 459 MWth - Première divergence : 1 / 1996 -

Available in english only


Event Number : 53092

Facility : WATTS BAR Region : 2 State : TN Unit : [2] - RX Type : [2] W-4-LP

Event Date : 11/26/2017 Event Time : 12:25 [EST] Last Update Date : 11/26/2017 Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(iv)(A) - ECCS INJECTION Person (Organization) : LADONNA SUGGS (R2DO)

Initial PWR  : 0 % Current PWR  : 0 %

Event Text

UNPLANNED EMERGENCY CORE COOLING SYSTEM (ECCS) INJECTION DURING A PLANNED SAFETY INJECTION TEST

"On November 26, 2017, at 1225 Eastern Standard Time (EST), the Watts Bar Nuclear Plant (WBN) Unit 2 experienced an unplanned ECCS discharge to the Unit 2 Reactor Coolant System (RCS) while de-pressurized, in Mode 5, with the Pressurizer vented to the Pressurizer Relief Tank. ECCS injection via the Boron Injection flow path occurred during planned Safety Injection system Engineered Safety Features Actuation System (ESFAS) testing. The Boron Injection flow path should have been isolated and should not have resulted in any injection flow to the Unit 2 RCS. Since the injection was not a part of the pre-planned test this is reportable under 10 CFR 50.72(b)(2)(iv), System Actuation.

"All other systems responded as expected in accordance with the ESFAS testing procedure. The unintended ECCS injection flow was isolated and flow through the Boron Injection path was verified to be stopped at 1232 EST. The Unit 2 Pressurizer level and pressure remained below any limits and no safety limits were challenged.

"NRC Resident Inspector has been notified."

https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2017/20171127en.html