Firefighting

With respect to firefighting, the ASN asked EDF in May 2001 to conduct an overall review of its policy. In response to this, EDF developed a new doctrine, which it put into practice in July 2003. The ASN duly noted this change and considered that it offered a better answer to what it wanted to see in terms of firefighting. It reckons in particular that the part about increased skills is just as important as that concerning organisational improvements.

At the request of the ASN, EDF further reinforced its doctrine in 2004, in particular by aiming for faster activation of the response teams as of the fire alarm, rather than after the fire has been confirmed. On certain sites, this will require drafting of a fire detection improvement plan. This plan is being gradually put in place as of 2004.

In 2005, the ASN reviewed the effectiveness of the plan of action proposed by EDF for deployment of this new doctrine and improvement of the reliability of fire detection. It considers that the firefighting response times have progressed on those sites which immediately deploy the response teams as soon as the alarm is sounded but that EDF does still need to focus on the actual duties of the response teams and on improving interfacing with the off-site emergency services.

In 2005, the ASN also ordered an assessment of the firefighting team response from an independent firm. It will include the conclusions of this assessment in the requests it submits to EDF in 2006.

Explosion risk

On the basis of the conclusions of the 2002 inspections on this subject, the incidents and the anomalies detected in the plants, the ASN asked EDF to improve the way in which the risks of explosion of internal origin are taken into account. It in particular asked EDF to look again at the existing systems for protection against the effects of an explosion of internal origin as part of the periodic safety review of the 900 MWe plant series on the occasion of the third ten-yearly outages and to initiate a similar approach for the other plant series.

The methodology developed by EDF, and in particular the application of this methodology to the hydrogen-related risk of internal explosion within the nuclear island buildings was analysed in 2005 by the Advisory Committee for nuclear reactors.

With regard to the risk of explosion originating outside the buildings, the ASN considers that EDF's overall approach is satisfactory. It however considers that this approach should be supplemented by a probabilistic approach and by a study of the safety consequences of the scenarios adopted.

Furthermore, with regard to the risk of explosion originating inside the buildings, EDF should complete its studies with review of gases other than hydrogen and by extending its analyses to buildings other than the reactor buildings.

In 2005, EDF continued to draft the studies reference system concerning the prevention of explosion risks, and the ASN has already formulated a number of remarks concerning it. The goal is for this reference system to be applied to the 900 MWe reactors' third ten-yearly outage.