26 février 2015
A 95 % de la puissance du réacteur, la commande d’une vanne principale n’a pas fonctionné, ce qui a entrainé un arrêt automatique du réacteur n° 1 en raison d’un niveau bas dans le générateur de vapeur "B". Les opérateurs ont rétabli l’équilibre du réacteur en température et en pression. Les barres de contrôle se sont correctement insérées dans le cœur. L’injection de sécurité a rétabli un niveau correct dans les générateurs de vapeur.
Type : PWR - Puissance : 2 940 MWth - Première divergence : 04/1978
Available in english only.
Event Number : 50851
Facility : NORTH ANNA
State : VA
Unit : [1] - RX Type : [1] W-3-LP
Event Date : 02/26/2015 - Event Time : 15:11
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 : 95 % Current PWR : 0 %
Event Text
AUTOMATIC REACTOR TRIP DUE TO FEEDWATER REGULATING VALVE FAILING CLOSED
"On February 26, 2015, at 1511 EST, with Unit 1 operating at 95% power in an end of cycle coastdown, the ’B’ Main Feedwater Reg Valve failed closed which resulted in a Unit 1 automatic reactor trip due to ’B’ Steam Generator low/low level. The operations crew entered the reactor trip procedure and stabilized Unit 1 in Mode 3 at normal operating pressure and temperature. All control rods fully inserted into the core following the reactor trip. This reactor protection system actuation is reportable per 10CFR50.72(b)(2)(iv)(B). The Auxiliary Feedwater pumps actuated as designed as a result of the reactor trip and provided makeup flow to the steam generators. The automatic start of the Auxiliary Feedwater system is reportable per 10CFR50.72(b)(3)(iv)(A) for the valid actuation of an ESF system. The Auxiliary Feedwater pumps were subsequently secured and returned to automatic. Decay heat is being removed by the condenser steam dump system. Unit 1 is in a normal shutdown electrical lineup.
"The NRC Resident Inspectors have been notified and are in the Control Room. The Louisa County Administrator will be notified."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150227en.html#en50851