 INES 2 |
Anomaly on the water recirculation circuits of French pressurised water reactors |
EdF confirmed to the French nuclear safety Authority (ASN) the possibility that, under some accidental conditions, recirculation sump filters be clogged by debris, in any of its PWRs.
These sumps, located in the bottom of the reactor containment building, collect water in the event of important leakage from the primary circuit during an accidental situation in order to return it in the safety injection circuit and ensure reactor cooling. Recent research work, conducted in France and abroad, had led the ASN to request EDF on October 9, 2003 to provide before end December 2003 its conclusions on the possibility of sump filters clogging and, if needed, on the corrective measures to be taken.
In its answer, EDF states that, in some very unlikely accidental situations (full rupture of a primary system piping), strainer sump clogging cannot be excluded, however it can be excluded for less important breaks. EDF specifies that equipment modifications of the installations are under study so as to correct the anomaly and will be submitted to ASN before April 2004, for an implementation from 2005 on. In tandem, EDF analyses various measures aiming at minimising the impact of the anomaly in accidental situation, waiting for the implementation of the modifications.
The ASN will review with the help of its technical support the IRSN the various proposals from the operator.
Taking into account the potential impact on the safety of the installations, the ASN has rated this generic event at INES level 2
Additional information (in French) available on: www.asn.gouv.fr (Communique de Presse 07 Jan 2004)
Event date: Wed, 31-12-2003
