Centre‑Val de Loire 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 nuclear power plant 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 the 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 adopted 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 ASNR considers that the performance of the Chinon NPP with regard to nuclear safety, radiation protection and environmental protection is in line with the general assessment of EDF plant performance. In the area of nuclear safety, ASNR considers that the results for 2025 are broadly stable compared with those for 2024. Performance in the areas of reactor operation and periodic test management remained at a satisfactory level. In particular, the site demonstrated good control over the operation of the facilities during the major influx of green algae in the Loire at the end of summer 2025. ASNR will nevertheless remain vigilant to ensure that the operational experience feedback from this event is taken into account by EDF. While progress has been made in fire risk management, the assimilation and preparation of activities by those involved need to be improved. Regarding maintenance activities, the equipment inspected appeared to be in good condition, but ASNR noted a lack of rigour in the application of the relevant rules, as well as in activity monitoring and oversight operations. ASNR considers that the radiation protection performance of the Chinon NPP has declined slightly. Personnel contamination rates remain among the lowest of EDF NPPs and radiological zoning appears to be under control. However, improvements are expected in the management of the containment of radioactive materials and the performance of industrial radiography work, both of which were the cause of significant events reported in 2025. The environmental performance of the Chinon NPP is generally satisfactory. The site controls its discharges and the containment of liquid hazardous substances, although the management of associated records needs to be improved. Waste management is also lagging behind, particularly in terms of compliance with storage conditions, traceability of operations, and consistency between internal procedures and practices in the field. In 2026, the site must therefore continue to take steps to treat and eliminate the waste from reactor maintenance that has accumulated over several years. Lastly, corrective action is expected in the short and medium term to ensure that the samples taken at the downstream multi-parameter station at the Chinon NPP are always representative of the site’s discharges. With regard to occupational safety, based on inspections concerning the management of workplace ventilation and air treatment systems, electrical equipment, lifting equipment, and prevention of lead exposure risks, ASNR considers that the action plans implemented by the site must continue in order to correct the deviations identified. 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 “non-integrated” 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 12 of the full ASNR 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 ha no objection to the continued operation of BNIs 133 (Chinon A1 reactor), 153 (Chinon A2 reactor) and 161 (Chinon A3 reactor). ASNR will verify during the assessment of the decommissioning files for these reactors, submitted by EDF at the end of 2022 and still being assessed, that the decommissioning operations will be carried out under suitable conditions of safety and radiation protection, within controlled time frames. 52 ABSTRACTS – ASNR Report on the state of nuclear safety and radiation protection in France in 2025
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