28 mai 2013
Arrêt manuel du réacteur n° 2 qui fonctionnait à 98 % de sa puissance. Cet arrêt manuel a été réalisé suite à une baisse du niveau de vapeur d’eau dans les générateurs de vapeur. La baisse de niveau est elle-même survenue suite à l’enclenchement transitoire du système principal d’alimentation en eau. Ce transitoire est intervenu suite à l’indication erronée de la fermeture d’une soupape de décharge. Le cœur étant critique, les systèmes de protection du réacteur se sont enclenchés.
1ère divergence juin 1980 - Type PWR - P : 940 MW
Available in english only.
State : VA - Unit : [2] RX Type : [2] W-3-LP,[3] M-4-LP Event Date : 05/28/2013 - Event Time : 15:07
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 : 98 % Current PWR : 0 %Hot Standby
Event Text
MANUAL REACTOR TRIP DUE TO A FEEDWATER TRANSIENT
"On May 28, 2013, at 1507 [EDT], Unit 2 was manually tripped from approximately 98 percent power due to decreasing steam generator levels as a result of a main feedwater system transient. The main feedwater system transient was initiated when the ’C’ Main Feedwater Pump Discharge Motor-Operated Valve, 2-FW-MOV-250C, spuriously closed. The cause of the spurious closure of 2-FW-MOV-250C is unknown at this time.
"The Operations crew entered the reactor trip procedure and stabilized Unit 2 in Mode 3 at normal operating temperature and pressure. All control rods fully inserted into the core following the reactor trip. The reactor protection system actuation is reportable per 10CFR50.72(b)(2)(iv)(B). The Auxiliary Feedwater (AFW) pumps actuated as designed as a result of the reactor trip and provided makeup flow to the steam generators. The automatic start of the AFW system is reportable per 10CFR50.72 (b)(3)(iv)(A) for a valid actuation of an ESF system. The AFW pumps were subsequently secured and returned to automatic. Decay heat is being removed by the condenser steam dump system. Unit 2 is in the normal shutdown electrical line-up.
"Unit 1 was not affected by this event."
The licensee notified the NRC Resident Inspector.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2013/20130529en.html
Event number : 49075