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Etats-Unis : Callaway : Fuite du circuit de refroidissement




23 juillet 2015


La fuite a été évaluée à 6,8 Litres / minutes soit un niveau supérieur à la limite réglementaire fixée à 3 l/m. Cette fuite a été détectée suite à l’élévation du niveau des radiations ainsi qu’à la baisse de niveau du réservoir de liquide de refroidissement. L’origine du panache de vapeur n’a pu être identifiée pour ne pas compromettre la sécurité des ouvriers et le réacteur est entré en phase d’arrêt à 6h.

Type : PWR - Puissance : 3 565 MWth - Première divergence : 10/1984

Available in english only.


Event Number : 51253

Facility : CALLAWAY - State : MO

Unit : [1] - RX Type : [1] W-4-LP

Event Date : 07/23/2015 - Event Time : 01:15

Emergency Class : NON EMERGENCY 10 CFR Section : 50.72(b)(2)(i) - PLANT S/D REQD BY TS 50.72(b)(2)(xi) - OFFSITE NOTIFICATION

Initial PWR : 100 % - Current PWR : 0 %

Event Text

INITIATION OF PLANT SHUTDOWN DUE TO RCS LEAKAGE

"On July 23, 2015 at 0115 [CDT], Callaway Plant initiated a shutdown required by Technical Specifications (TS). At 2139 [CDT] on July 22, 2015, TS 3.4.13 Condition A was entered due to unidentified RCS leakage being in excess of the 1 gpm TS limit. The leak was indicated by an increase in containment radiation readings, increasing sump levels, and decreasing levels in the Volume Control tank (VCT).

"A containment entry identified a steam plume ; due to personnel safety the exact location of the leak inside the containment building could not be determined.

"At this time radiation levels inside [the] containment are stable and slightly above normal. There have been no releases from the plant above normal levels.

"The [NRC] Senior Resident Inspector was notified."

* * * UPDATE PROVIDED BY ROB STOUGH TO JEFF ROTTON AT 1757 EDT ON 07/23/2015 * * *

"Callaway entered TS 3.4.13 Condition B at 0053 [CDT on July 23, 2015] for the subject leakage since reactor coolant pressure boundary leakage could not be ruled out by visual inspection. The estimated leak rate when the decision was made to shut down the plant was approximately 1.8 gpm. The plant entered Mode 3 at 0600 CDT.

"Additionally, at approximately 1315, it was determined that the duration of the required outage would be greater than three days, thus requiring notification to the Missouri Public Service Commission. This offsite notification is reportable to the NRC [per 10CFR50.72(b)(2)(xi)], and the above table has been updated to reflect this reporting requirement."

The licensee notified the NRC Resident Inspector.

http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2015/20150724en.html#en51253