The order of 31 December 1999 sets the general conditions to be met by BNIs concerning environmental protection and requires the performance of work to ensure conformity. A more complete description of the provisions of this order is given in chapter 5, point 5.1.

For the particular case of the KER/TER/SEK effluent tank retention areas, the measures proposed by EDF in the files submitted by the deadline of 15 February 2002 were not considered to be acceptable by the ASN, which led EDF to propose new preventive measures. On the basis of the new provisions, considered to be equivalent to the requirements of article 14 of the order, the ASN decision of 17 August 2004 set a deadline of 15 February 2006 for conformity. EDF nonetheless stated that it could not meet this deadline and asked for authorisation to complete conformity of all nuclear power plants in mid-2007. This request is currently being reviewed by the ASN.

The impact of installation noise is regulated: the difference between the ambient noise measured when the installation is operating and the residual noise level measured when it is stopped is subjected to a limit and, for example, must not exceed 3 dB(A) at night.

EDF has carried out noise measurements on all the plants. The study showed that ten plants were in conformity while there were nonconformities at Belleville, Bugey, Chinon, Civaux, Dampierre, Golfech, Nogent-sur-Seine, Penly and Saint-Laurent-des-Eaux. The main noise sources are the cooling towers, the turbine halls, the BAN stacks and the transformers. EDF considers that noise linked to the presence of a weir or cooling towers is comparable to natural noise such as a waterfall.

EDF defined an overall corrective approach based on technical-economic soundproofing studies. For each noise source, EDF looked for partial or total soundproofing techniques and then assessed their effectiveness and technical feasibility. It became apparent that ensuring strict conformity by the nine plants was not possible in acceptable technical and economic conditions, or would imply drawbacks, for example in terms of safety or health.

EDF consequently focused its strategy on three key areas: a reduction and if possible elimination of distinct tones, preferential treatment of noise sources of an industrial nature and, whenever possible, no aggravation in the event of development of the installations or plants. EDF agreed to ensure that the level of protection reached was maintained over time. Furthermore, for those plants with cooling towers or a river weir, EDF proposed including their contribution in the residual noise.

The justifications provided by EDF are currently being reviewed by the ASN.