The French safety authority (ASN) issues specifications for “complementary safety evaluation” of French nuclear installations in the light of the accident of Fukushima

ASN believes that it is essential to learn from the accident which occurred at Fukushima-Daiichi nuclear power plant, as it has been undertaken after the Three Mile Island and the Chernobyl accidents.

The in-depth experience feedback will involve a long process stretching over several years. Some lessons, however, can already be learned.

On 5 May 2011, the ASN Commission adopted 12 decisions requiring to licensees of French nuclear installations to conduct a complementary safety evaluation of their installations in the light of the accident which occurred in Fukushima.

The French High Committee for Transparency and Information on Nuclear Security (HCTISN) has contributed to the decisions’ drafting; during its extraordinary meeting which HCTISN held on 3 May 2011, this committee approved the specifications submitted by ASN.

This complementary safety evaluation will consist in a targeted reassessment of the safety margins of nuclear installations in the light of the events which occurred in Fukushima: extreme natural conditions challenging the installation safety functions and leading to a severe accident.

Three main aspects need to be reported in this assessment :

• Provisions taken in the installation design basis and installation compliance with its current licensing requirements;
• Robustness of the installation beyond its design basis; the licensee shall identify scenarios leading to a sudden degradation of accidental sequences and will describe preventive measures aimed at avoiding them;
• Any potential modification likely to improve the installation safety level .

These complementary safety evaluations will concern all French nuclear installations but will focus, first of all, on nuclear power plants.

Licensees must submit their reports to ASN by 15 September 2011.

ASN and its technical support organization, IRSN (Institute of Radiation Protection and Nuclear Safety) will review them by 15 November 2011.

This approach supplements the safety regulation currently in force. ASN is devoting significant resources to this effort.