ASN Report 2018

CENTRE-VAL DE LOIRE REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION 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 shut down or undergoing decommissioning. On the south side of the site, the Chinon B nuclear power plant 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 Gas-Cooled Reactors designated Chinon A1, A2 and A3, are currently being decommissioned. The site also accommodates the AMI (Irradiated Materials Facility), designed for the expert assessment of activated or contaminated materials, whose activities have now been entirely transferred to a new laboratory – the LIDEC – and the MIR (Inter-Regional fresh fuel Warehouse). Chinon NPP Reactors B1, B2, B3 and B4 in operation ASN considers that the safety and environmental protection performance of the Chinon NPP on the whole is in line with ASN’s general assessment of EDF, and that the radiation protection performance is above the national average. ASN considers that the site is maintaining a satisfactory level with regard to nuclear safety. It underlines improvements in the overall upkeep of the worksites and the completeness of the documents examined during various inspections. Progress is required in the preparation of the risk analyses and in the performance of the system configuring and periodic test activities, which have been the cause of several significant events. Furthermore, the NPP’s organisation for detecting deviations and justifying their remediation time frames is not sufficiently robust and must be improved. Lastly, the site must improve its management of the risks relating to fire, explosion and lightning in order to ensure the conformity of its installations with the associated regulations. The radiation protection performance of the Chinon site is satisfactory, as witnessed by good results in terms of dosimetry and radiological cleanliness. The radiation protection rules are generally well integrated at the preparation stage and during the performance of work in controlled areas, despite the detection of a few deviations. Although comparable with the national average, the environmental performance of the Chinon site can be improved on the whole. Although the maximum discharge values for gaseous and liquid effluents are respected and the number of environment-related significant events is low, numerous regulatory deviations concerning catering for the legionella and amoeba risks and waste management were noted. Reactors A1, A2 and A3 undergoing decommissioning The graphite-moderated Gas-Cooled Reactor (GCR) series comprises six reactors, including the Chinon A1, A2 and A3. These first-generation reactors used natural uranium as the fuel and graphite as themoderator. They 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 amuseum since 1986. Chinon A2 D is also partially decommissioned and houses Groupe Intra, which operates robotised 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» and the Chinon A2 reactor pressure vessel would be decommissioned first. This new strategy is currently being examined by ASN (see chapter 13). The operations to decommission the exchangers (first step in decommissioning of the facility) on the Chinon A3 reactor began several years ago. After an interruption of several months due to the presence of asbestos, decommissioning of the heat exchangers of the south premises of Chinon A3 was completed in June 2018. Regarding decommissioning of the heat exchangers of the north premises, the parts containing asbestos had to be cleaned before starting the operations in 2018. ASN considers that the level of safety of the Chinon nuclear installations undergoing decommissioning (Chinon A1, A2 and A3) is generally satisfactory. The inspections carried out in 2018 revealed satisfactory control of reactor containment and compliance with EDF’s commitments concerning nuclear waste management. Significant improvements have been made in waste monitoring and management. The removal of a large quantity of waste packages resulting from the decommissioning operations is a positive point in this respect. ASN report on the state of nuclear safety and radiation protection in France in 2018  43