Electricite de France (EDF) has told nuclear safety authority ASN (Autorité de Sûreté Nucléaire) that it wants to change its decommissioning approach for France's six first-generation gas-cooled reactors from wet dismantling to dry dismantling. EDF plans to undertake the complete dismantling of one of the six reactors before beginning dismantling the other five. This will allow it to benefit from the combined experience. EDF said the dismantling of all peripheral reactor equipment at the six units, which were permanently shut down between 1973 and 1994, should be completed within 15 years.
ASN had called for a review of EDF's plans for the six units and will now examine the revised strategy. The six units are: St Laurent A-1 (390MWe); St Laurent A-2 (465MWe); Chinon A-1 (70MWe); Chinon A-2 (180MWe); Chinon A-3 (360MWe); and Bugey-1 (540MWe). They are all UNGG (Uranium Naturel Graphite Gaz) plants, an obsolete French reactor design, which were graphite moderated, cooled by carbon dioxide, and fuelled with natural uranium metal.
The three reactors at Chinon (A-1, A-2, and A-3) operated from the early 1960s and A3 were shut down in 1973, 1985 and 1990. Their partial dismantling was completed in 1984, 1992 and 2007. Units A-1 and A-2 at St Laurent were commissioned in 1969 and 1971 and shut down in 1990 and 1992. Defuelling of the two reactors was completed in 1992 and 1994. Bugey-1 was commissioned in 1972 and shut down in 1994.
The first generation of French NPPs were UNGGs, as was Vandellos-1 in Spain, which was permanently shut down in 1990. There were also three similar UNGG reactors at the Marcoule nuclear site in southern France. They were owned and are being decommissioned by the French Alternative and Atomic Energy Commission (CEA).
The company had originally planned to dismantle the reactors using underwater techniques, but has now decided to dismantle them in air. "This new strategy means decommissioning of certain reactors will be pushed back by several decades with respect to the strategy announced by EDF in 2001 and updated in 2013the ASN noted.
The ASN acknowledged receipt of EDF's new strategy and asked the company to make it public and provide a detailed justification for this change, while demonstrating compliance with the legislation concerning decommissioning all UNGGs in the shortest period possible. It also requested a detailed programme of works for the coming 15 years.