Until recently, the generic strategy adopted by EDF for decommissioning of its nuclear power plants, was that of deferred complete decommissioning. This strategy consisted in extracting the fissile material, removing the easily recoverable parts, reducing the contained zone to a minimum and fitting out the external barrier. Complete decommissioning of the installation was then envisaged by EDF after several decades of containment, to take advantage of the natural radioactive decay. An approach of this type had its drawbacks, notably in that it could lead to a gradual loss of knowledge of the installation, as its operator departed, which could be prejudicial to the decommissioning operations. The ASN asked EDF to review this strategy and to evaluate the feasibility of reducing the time needed to undertake complete decommissioning work.

After an initial evaluation submitted in November 1999, EDF decided to revise its strategy for the EL4 reactor, undertaking to carry out complete decommissioning of the reactor soon after completion of the partial decommissioning operations currently in progress.

Then in April 2001, EDF decided to adopt this new decommissioning strategy for all its decommissioned nuclear installations (Brennilis, Bugey 1, Saint-Laurent A, Chinon A, Chooz A and Superphénix), based on complete decommissioning of the reactors, with no standby period. It thus provides for complete decommissioning of these reactors by 2025.

To ensure the success of the new complete decommissioning programme for these 9 first generation reactors, EDF is relying on the CIDEN (Deconstruction-Environment Engineering Centre), an engineering unit based in Lyons and dependent on the DIN (nuclear engineering division), which has been operational since 2001.

In addition to the data to be transmitted in the documents specific to the various sites, the ASN feels that EDF had sent all the expected answers to the Advisory Committee on 24 March 2004, concerning the decommissioning strategy to be applied to the first generation of EDF reactors.

In its letter of 30 September 2005 sent to the Chairman of EDF, ASN in particular stressed the need for EDF to ensure that reactor decommissioning takes place in good technical and economic conditions. More particularly, in the case of the first generation reactors, priority must be given to decommissioning Bugey 1 and Saint-Laurent A1 et A2, in compliance with the schedule proposed by EDF. With regard to the pressurised water reactors currently in operation, EDF must start looking at decommissioning conditions, taking account of NPP standardisation, the number of installations and the dates envisaged for their shutdown.

In a letter dated 9 February 2004, the Nuclear Safety Authority authorised EDF to set up a system of internal authorisations for the installations concerned by the decommissioning programme. This approach is primarily designed to meet a strong demand for constant updating of the safety reference system of an installation. Setting up such a system therefore enables the licensee to make changes to the reference system which do not compromise the safety demonstration.

In September 2005, EDF sent the initial results after 18 months of use of the internal authorisation system for the decommissioning programme. EDF incorporated experience feedback from the event which had led the ASN to suspend a decommissioning worksite at Chooz A, which was the first occasion the internal authorisations system was used. The ASN considers that the organisation put in place by EDF now works satisfactorily.

The EL4 nuclear reactor, which entered service on 23 December 1966, finally ceased all production of electricity on 13 July 1985. This reactor was an industrial prototype, built and operated jointly by the CEA and EDF. As part of the partial decommissioning process for this installation, the 31 October 1996 decree authorised modification of the existing installation, converting it into a facility for interim storage of its own equipment left on the site and thus created a new basic nuclear installation called EL4-D. On the basis of a study defining the various possible options for final decommissioning earlier than planned, EDF on 22 July 2003 submitted an application for final shutdown and decommissioning of the EL4-D installation.

In 2005, EDF carried out preparatory work on the site in advance of future decommissioning work inside the reactor containment, modification of the reactor containment and reactor block ventilation system and cutting work to isolate the CO2 system from the reactor bloc. In the light of the inconclusive results of the clean-up operation on the effluent treatment station sub-soil already carried out and the corresponding safety risks, the work had to be suspended in order to define a new operating methodology.

• Chinon A1D, A2D and A3D reactors

The old Chinon A1, Chinon A2 and Chinon A3 reactors were partially decommissioned and transformed into storage facilities for their own equipment. These operations were authorised by the decrees of 11 October 1982, 7 February 1991 and 27 August 1996, respectively. These installations are currently in the care and maintenance phase.

The new water intake and liquid and gaseous effluent discharge authorisation was signed on 17 August 2005. The Chinon A installations should be brought into conformity so that gaseous discharges can be measured during the forthcoming worksites. The licensee has also started the administrative formalities prior to demolition of the Chinon A pumping stations, which should take place during the course of 2006. In 2005, EDF began demolition of the conventional buildings and evacuation of nuclear waste continued in the conditions initially planned.

• Saint-Laurent-des-Eaux A1 and A2 reactors

The decree authorising final shutdown operations for the two reactors was signed on 11 April 1994. In 2005, EDF began core drilling of the graphite and the concrete of the caisson in order to consolidate the radiological inventory.

• Bugey 1 reactor

The decree authorising final shutdown operations was signed on 30 August 1996. In 2005, the licensee completed packaging of the graphite sleeves and removal of all the containers to the Aube centre. Decommissioning work on the CO2 treatment areas began in May 2005.

In October 2005, EDF submitted an application for the complete decommissioning authorisation. Review of these documents is currently in progress.