ASN Report 2022

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 900 MWe reactors; the first two constituting BNI 107 were commissioned in 1982-1983, while the second two constituting BNI 132 were commissioned in 1986‑1987. To the north, the three old graphite-moderated GCRs designated Chinon A1, A2 and A3, are currently being decommissioned. The site also accommodates the AMI, currently being decommissioned, whose former activities of expert assessment of activated or contaminated materials have been entirely transferred to a new laboratory called “the Lidec”, and to MIR. Chinon nuclear power plant Reactors B1, B2, B3 and B4 in operation ASN considers that the performance of the Chinon NPP is in line with the general assessment of EDF in the areas of safety, radiation protection and the environment. Progress has been noted in 2022, particularly in the area of safety. The results in the area of radiation protection, however, must be consolidated. With regard to safety, ASN observes that the performance in normal operational management is improving. Operational management in “incident” and “accident” situations is satisfactory, even if improvements are expected in the traceability of staff training and in the emergency situation documentation. Furthermore, particular attention is to be paid to the inspections of the main primary system and the implementation of the post-Fukushima measures. As far as maintenance of the installations is concerned, the site’s performance is stable and satisfactory. Improvements to enhance the reliability of the maintenance operation supporting documents are nevertheless expected. 2022 was marked by an outage associated with the problem of stress corrosion of reactor 3, on which the various inspections have revealed no major anomalies. ASN considers that the radiation protection performance of the Chinon NPP remains relatively satisfactory. The radiological cleanliness of the inspected work sites did not raise any particular remarks. Progress is however expected in the cordoning off of radiography work areas, and in the effective application of the prevention measures chosen with regard to radiation protection and for the use of the radiographic work regimes. The environmental performance of the Chinon NPP is improving. The maximum discharge values set for gaseous and liquid effluents are observed. However, the monitoring of contractors on short-term work sites must be improved in order to comply with the environmental protection requirements. In addition, the management of liquid containment can be further improved. With regard to labour inspection, 2022 was marked by an accident which led to two inquiries, one of which necessitated numerous investigations conducted in collaboration with the gendarmerie of Chinon. In addition to this, on the Chinon site – as with all the Centre-Val de Loire region NPPs – ASN maintained its joint inspections between the labour inspectorate and safety inspection in order to benefit from the existing synergies. This was the case in particular with an inspection of the radiation protection skills centre, which evidenced a few minor deviations without calling into question the organisation adopted by the NPP. 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 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” GCR reactors. They were shut down in 1973, 1985 and 1990 respectively. Reactors A1 and A2 were partially decommissioned and transformed into storage facilities for 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 is decommissioning “in air” and the Chinon A2 reactor pressure vessel would be decommissioned first (see chapter 13 of the full ASN Report). In this context, ASN has analysed the periodic safety review concluding reports submitted by EDF for the six GCR reactors, supplemented further to the requests 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). It will verify during the examination of the decommissioning files for these reactors, submitted by EDF at the end of 2022, that the decommissioning operations are carried out under suitable conditions of safety and radiation protection, within controlled time frames. ABSTRACTS – ASN Report on the state of nuclear safety and radiation protection in France in 2022 51 Regional overview of nuclear safety and radiation protection • CENTRE-VAL DE LOIRE •