French regulator reviews Chooz A decommissioning

31 May 2022

The Chooz A nuclear reactor, built into a hillside, is the first pressurised water reactor (PWR) to be decommissioned in France. In its latest review of progress the French nuclear regulator says monitoring of the action plan on site could be improved, but it approved the continued decommissioning activities.

Chooz A is on the right of this picture built into the hillside (Image: EDF)

The 300 MW reactor was the first PWR built in France in a joint venture with Belgium, supplying electricity to both countries from 1967 to 1991. Responsibility for decommissioning was transferred to EDF and its dismantling began in 1999 with the removal of fuel, draining the circuits and the dismantling of the engine room, pumping station and nuclear buildings outside the cavern - as the facility was modified into a storage site for its own equipment.

Its complete decommissioning was authorised in 2007, including the dismantling of the primary circuit of the reactor. Decommissioning of the reactor pressure vessel began in 2016.

France's nuclear safety regulator, the Autorité de Sûreté Nucléaire (ASN), said that at the moment "the main operation in progress is the dismantling of the vessel’s internal equipment, which is carried out under water".

ASN said that the 2007 decree requires EDF to monitor the water in the cave "until an effluent concentration of tritium compatible with the cessation of their possible treatment and their control before discharge".

The last stage of the process "will include the complete dismantling of the residual equipment of the caves and the effluent treatment station, the demolition of the buildings and the redevelopment of the site".

The regulator's report added that although the safety issues presented by the facility "given the progress of the dismantling operations" are relatively limited, the issue of worker protection remained.

ASN said its inspection "made it possible to underline the good performance of the installation and relevant actions implemented for fire fighting and waste management. However it showed that monitoring of the action plan on site could be improved".

It stressed the need for detailed checks on equipment and structures and said that on the management of certain residual pollution there were some gaps and some parts lacked precision. It also said that "the cases of internal contamination observed in recent years" showed that measures brought in by EDF in 2018 "to control the risk of contamination had not fully achieved their objectives".

ASN concluded that, subject to the requests sent to EDF, it had no objection to the continuation of the decommissioning process for the years to come.

Researched and written by World Nuclear News