Chinon site Situated in the municipality of Avoine in the Indre‑et‑Loire département, on the left bank of the river Loire, the Chinon site accommodates various nuclear installations, some in operation, others undergoing decommissioning. On the south side of the site, the Chinon B NPP comprises four in-service reactors of 900 MWe; the first two commissioned in 1982 and 1983 constitute BNI 107, while the second two commissioned in 1986 and 1987 constitute BNI 132. To the north, the three old graphite-moderated GCRs designated Chinon A1, A2 and A3, are currently being decommissioned. The site also accommodates MIR and the irradiated materials facility AMI which is currently being decommissioned and whose former expert assessment activities have been transferred to a new laboratory at Chinon called “Lidec”. 1. Among the possible scenarios for decommissioning the highly activated or contaminated structures, we find decommissioning “in air” and decommissioning “under water”. In the case of the GCRs, the “under water” approach consists in filling the reactor core (reactor pressure vessel) with water in order to benefit from the protective effect of a layer of water with respect to the radiation-related risks, but it is more complicated to implement than the “in air” approach. In view of the major technical difficulties (sealing of the reactor pressure vessel and treatment of the contaminated water), but also the technological advances bringing other solutions, such as remote operation, EDF has finally adoptyed the decommissioning “in air” scenario, which overcomes the problems linked to the use of water. Chinon nuclear power plant Reactors B1, B2, B3 and B4 in operation ASN considers that the environmental performance of the Chinon NPP stands out positively, while the nuclear safety and radiation protection performance is in line with ASN’s general assessment of the EDF plants. With regard to nuclear safety, ASN considers that the results for 2024 are in line with the average for the NPPs but show a decline compared with 2023. The reason for this is that although performance in the area of operational management of the reactors remained at a satisfactory level, improvements are required in the management of the fire risk and the availability of systems involved in controlling reactivity. The site’s performance in maintenance of the facilities deteriorated over the year 2024. The equipment items inspected appear to be in good condition but the quality of the first-level analyses has regressed and several events have brought to light a lack of skills or training of the actors involved. ASN considers that the radiation protection performance of the Chinon NPP is progressing. The level of worker contamination remains among the lowest of the EDF NPPs. The measures taken in response to the difficulties encountered in performing industrial radiography work in the last few years seem to have borne fruit in 2024. ASN nevertheless notes an increase in the number of triggerings of radiation portal monitors at the site exit and in the detection of contamination on the site roads, despite some progress being observed. The environmental performance of the Chinon NPP is progressing and rankse among the best of the EDF plants. The site controls its discharges and the containment of hazardous liquid substances. Waste management however remains below expectations. The year 2025 should be used to continue the treatment and removal of the waste resulting from reactor maintenance that has been accumulating on the site for several years. The year 2024 was marked by numerous accidents requiring labour inspection investigations by ASN, which revealed the need to improve some worksite procedures. ASN considers that the site must improve worksite preparation, particularly by taking full account of all risks, such as those related to potential asbestos and lead exposure. Lastly, ASN notes that the site has made significant efforts to address the risk of falls from height, through the implementation of a verification of all relevant collective protection measures. Reactors A1, A2 and A3 undergoing decommissioning The graphite-moderated GCR series comprises six reactors, including Chinon A1, A2 and A3. These first-generation reactors used natural uranium as the fuel, graphite as the moderator and were cooled by CO2 gas. This plant series includes “integrated” reactors, whose heat exchangers are situated under the reactor core inside the vessel, and “nonintegrated” reactors, whose heat exchangers are situated on either side of the reactor vessel. The Chinon A1, A2 and A3 reactors are “non-integrated” GCRs. They were shut down in 1973, 1985 and 1990 respectively. Reactors A1 and A2 have been partly decommissioned and transformed into facilities for the storage of their own equipment (Chinon A1 D and Chinon A2 D). These operations were authorised by the Decrees of 11 October 1982 and 7 February 1991 respectively. Chinon A1 D is partially decommissioned at present and has been set up as a museum – the Museum of the Atom – since 1986. Chinon A2 D is also partially decommissioned and, until the end of 2022, housed GIE Intra (robots and machines for interventions on accident-stricken nuclear installations). Complete decommissioning of the Chinon A3 reactor was authorised by the Decree of 18 May 2010, with a decommissioning “under water” scenario. In March 2016, EDF announced a complete change of decommissioning strategy for its definitively shut down reactors. In this new strategy, the planned decommissioning scenario for all the reactor pressure vessels involves decommissioning “in air”(1) and the Chinon A2 reactor pressure vessel would be decommissioned first (see chapter 14 of the full ASN Report). In this context, ASN has analysed the periodic safety review concluding reports submitted by EDF concerning the six GCRs, supplemented further to the request from ASN. On completion of its analysis, ASN indicated in December 2021 that it has no objection to the continued operation of BNIs 133 (Chinon A1 reactor), 153 (Chinon A2 reactor) and 161 (Chinon A3 reactor). The Authority for Nuclear Safety and Radiation 52 ABSTRACTS – ASN Report on the state of nuclear safety and radiation protection in France in 2024 Regional overview of nuclear safety and radiation protection CENTRE-VAL DE LOIRE
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