6 février 2015
Cette perte d’eau est intervenue lors de travaux de préparation à une maintenance de week-end sur ce système de refroidissement. Malgré le niveau très bas d’eau relevé au moment du problème, ainsi que l’enclenchement du dissipateur de chaleur ultime, les conditions d’arrêt du réacteur se seraient effectuées normalement avec insertion correcte des barres de contrôle et un bon niveau d’eau de refroidissement du réacteur. Des investigations sont menées pour déterminer la cause du problème.
Type : Fukushima Daïchi (BWR Mark I ) - Puissance : 2 957 MWth - Première divergence : 01/1970
Available in english only.
Event Number : 50792
Facility : DRESDEN - State : IL
Unit : [2] - RX Type : [2]
Event Date : 02/06/2015 - Event Time : 12:27 Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(iv)(A) - ECCS INJECTION 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION
Initial PWR : 100 % Current PWR : 0 %
Event Text
AUTOMATIC REACTOR SCRAM DUE TO LOSS OF FEEDWATER
"At 1227 CST on 06 Feb 2015, Dresden Unit 2 automatically scrammed due to a Reactor Water Level transient. Set up activities for weekend maintenance were being performed on the feedwater system at the time of the event.
"All rods inserted to their full-in positions.
"Systems operated as expected.
"Reactor vessel inventory and pressure are being maintained in normal control bands. The ultimate heat sink was maintained.
"The source of the transient was a loss of Feedwater Level Control and the reactor automatically scrammed on low reactor water level. Cause of the failure is under investigation. All three feed pumps tripped as a result of the transient. The 2B reactor feed pump was restored following the transient in accordance with station operating procedures. Level is being maintained with normal feedwater.
"High Pressure Coolant Injection initiated on a valid low-low reactor water level. Manual operator action was taken to prevent unneeded injection into the reactor coolant system.
"Group 2 Primary Containment and Group 3 Shutdown Cooling and Reactor Water Clean-up system isolations occurred as expected.
"Unit 2 and 2/3 [swing diesel] EDGs started as expected, but did not load onto their associated busses as offsite power was maintained."
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150209en.html