Assessment of nuclear pressure equipment conformity The NPE of the Flamanville reactor includes that making up the main primary and secondary systems presented in point 2.2 (reactor pressure vessel, SG, pressuriser, reactor coolant pumps, piping, safety valves) but also that constituting other parts of the NSSS. During the course of 2022, ASN continued to assess the conformity of the NPE design of the MPS and MSS. As in 2021, it in particular checked performance of the operations to repair the main steam lines subject to the break preclusion requirements, as well as the operations performed on the other lines not subject to this requirement, with more extensive involvement of the Bureau Veritas Exploitation organisation. ASN also continued to analyse the deviations which affected the post-weld heat treatment of the connection welds on the SG and pressuriser components carried out in Framatome’s Saint-Marcel plant, as well as on the main secondary system lines carried out on the Flamanville site, where a high level of activity will continue in 2023. EDF and Framatome intend to carry out repairs when this can be envisaged or, failing which, to demonstrate that the conformity of the equipment is not compromised. In 2022, ASN also continued to assess the conformity of the main steam lines with the break preclusion requirements, as well as the quality of the welds on three main system nozzles, around which EDF has decided to install a retaining collar. In the event of rupture of the nozzle set-in weld, this collar would limit the size of the resulting break. The consequences of this break would then be covered by the reactor’s existing safety studies. ASN considers that the solution proposed by EDF is acceptable. The examination of the justification of the production quality of these three nozzles has yet to be finalised. Oversight of construction, start-up tests and preparation for operation Oversight of construction has repeatedly revealed faults in construction quality, requiring corrective measures. EDF carried out additional verifications which were the subject of discussions with ASN. In 2022, ASN continued to examine the programme of additional inspections and the results of the review carried out by EDF. In 2023, EDF should be issuing the results of these actions and draw up the corresponding conclusions. ASN considers that EDF’s equipment conservation strategy is satisfactory, provided that EDF carries out additional maintenance to prevent ageing of the equipment and sets up an equipment inspection programme at the end of the conservation phase, to check the effectiveness of the steps taken and detect any latent defects. The conservation activities were inspected on-site by ASN. In 2022, ASN initiated a campaign of inspections (3 in 2022) on completion of the installation, in order to check that EDF is fully cognizant of the activities still to be carried out (end of assembly, modifications, tests, deviations, etc.) and has scheduled them prior to commissioning of the reactor. ASN also continued its oversight of preparation for operation and in 2023 intends to conduct an in-depth inspection of several days, to obtain a more exhaustive picture of the preparations of the future licensee, before commissioning of the reactor. This in-depth inspection will notably concern the definition and implementation of the operational organisations, the management and assimilation of the required skills, and the drafting and operational nature of the operating documentation. In June 2020, EDF sent ASN a first version of the results of the installation start-up tests. These results are updated as and when the remaining tests are performed. ASN continued with examination of this document and its updates transmitted, in order to verify that the as-built installation complies with the hypotheses contained in the safety case. This examination will continue in 2023. In addition, during its inspections, ASN ensures that EDF has taken sufficient measures either to guarantee that the work carried out after the start-up tests does not compromise the results obtained during these tests, or to identify the tests to be repeated following this work. In 2022, ASN carried out 15 inspections of EDF on the Flamanville site, including a campaign of 4 inspections on MSS repairs and two inspections in the engineering departments. ASN also carried out labour inspections. The conclusions of these inspections are presented in the Regional Overview in the introduction to this report. CAMPAIGN OF INSPECTIONS 10 YEARS AFTER THE FUKUSHIMA DAIICHI NPP ACCIDENT Following the accident that struck the Fukushima Daiichi NPP on 11 March 2011, ASN asked EDF to carry out stress tests on its installations. These stress tests led, on 26 June 2012, to ASN adopting technical prescriptions applicable to each of the NPPs, in order to regulate the required safety improvements. Ten years after the adoption of these prescriptions, ASN conducted an inspection campaign in 2022 with the aim of checking the deployment of the safety improvements. Each NPP was thus inspected, along with the four regional bases of the Nuclear Rapid Intervention Force (FARN). The inspectors notably checked the installation of additional water and compressed air supplies, the new provisions and reinforcements in the event of an earthquake, the new back-up electrical power sources, the new provisions improving the safety of the fuel pool and the new mobile resources to monitor the environment in an emergency situation. The inspectors found that deployment of the safety improvements was on the whole as required with generally correct application of the technical prescriptions adopted in 2012. However, these inspections also demonstrated that the documentary baseline on the sites was not always up to date with all the safety improvements deployed. In addition, an occasional lack of rigorousness in the follow-up of the new equipment was recorded, along with shortcomings in the identification of certain new provisions needed for correct implementation of this equipment. After each of these inspections ASN sent improvement requests to EDF. 314 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 10 • The EDF Nuclear Power Plants 10
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