ASN Report 2020

In its construction site oversight activities, ASN devoted particular attention to the following subjects in 2020: ∙ preparation for and performance of the initial repairs of the main steam letdown line welds. ASN more particularly checked the production of the corresponding documentation, management of the skills of the workers involved and the supervisors of these operations, and checked compliance with the welding procedures; ∙ the preparation for and performance of the start-up tests for the various systems of the installation and EDF’s organisation for management of the overall tests; ∙ preparation for partial commissioning to allow the arrival of nuclear fuel within the perimeter of the installation and operation of the installation following this partial commission­ ing. ASN also carried out checks on the transport of fresh fuel assemblies; ∙ application of the strategy for the conservation, maintenance and testing of the equipment and structures present on the construction site until the reactor is commissioned. Owing to the postponements to reactor commissioning announced by EDF, ASN makes sure that EDF continues to pay close attention to defining and complying with the requirements corresponding to the conservation, maintenance and testing of the equipment already installed and the structures built; ∙ protection of the environment and more particularly the follow- ups to the tightened inspections performed on the subject in 2019; ∙ the radiation protection of workers during radiographic inspection of welds. Oversight of the Flamanville EPR reactor engineering activities In 2020, ASN carried out two inspections in EDF’s engineering departments regarding the performance of activities important for protection and their monitoring when performed by outside contractors. These inspections were carried out on the sites where these activities are performed. In January 2020, ASN thus conducted an inspection in the premises of Framatome, where the reactor protection system software is developed. During this inspection, ASN examined skills management, as well as the process for managing changes and deviations. In addition, in October 2020, ASN carried out an inspection in the premises of Edvance, where it examined the process for production and management of the documentation for incident and accident control. Labour inspection on the Flamanville EPR reactor construction site The actions carried out by the ASN labour inspectors in 2020 consisted in: ∙ performing checks on the contractors working on the site; ∙ answering direct queries from the employees; ∙ carrying out inquiries following occupational accidents; ∙ investigating requests for exemptions to provisions under the labour regulations. Application of the safety rules was regularly checked. Oversight of NPE design and manufacturing for the Flamanville EPR reactor During the course of 2020, ASN continued to assess the conformity of the design of the NPE of the main primary and secondary systems. Having observed inadequate justification and incomplete design files for this equipment, more specifically with regard to the risk assessments, choice of materials and in-service inspectability of the equipment, ASN held numerous technical meetings with Framatome (formerly Areva NP) in 2013 and 2014 in order to define the additional data to be provided. In 2015, Framatome began a revision of all technical design documentation for this Welds on lines of the main secondary systems of the Flamanville EPR reactor Major repairs are required on the welds on lines of the main secondary systems of the Flamanville EPR reactor. Some of these welds are located on the main steam lines, which are subject to a “break preclusion” approach, which assumes mechanical properties and a level of manufacturing quality that are particularly high. Eight of these welds are located in the annulus between the two containment walls of the reactor building. The difficult access conditions required the development of special intervention means and the qualification of specific welding, inspection and heat treatment processes. In 2020, ASN initiated its examination of the qualifications of these various processes and will issue a position statement on initiation of the welding operations at the beginning of 2021. Most of the other welds on the main steam lines to be repaired, of which there are about 50, are located in an environment with no access difficulties. In 2020, ASN initiated its examination of the qualification of the repair processes. EDF was able to initiate the repair of seven welds as of the summer of 2020. ASN is attentive to ensuring that the number of repairs made in parallel is compatible with the organisation of worksite surveillance. This work will continue until 2022. At the same time, EDF evaluated the quality of the other welds, in particular the Steam Generator (SG) feedwater lines. This work led EDF to decide to repair ten or so additional welds. ASN will issue a position statement on the scope of the welds to be repaired once EDF has submitted all the justifications. Implementation of the orbital TIG process – weld on the main secondary system ASN Report on the state of nuclear safety and radiation protection in France in 2020 317 10 – THE EDF NUCLEAR POWER PLANTS 10