enable the as-built installation to comply with the safety case for the duration of the project; ∙ ensuring that the licensee takes the necessary steps so that the teams in charge of operating the installation after com– missioning are well-prepared. To do this, ASN has set binding requirements regarding the design, construction and start-up tests for the Flamanville EPR reactor and for operation of the two Flamanville 1 and 2 reactors close to the construction site. As this is a nuclear power reactor, ASN is also responsible for labour inspection on the construction site. Lastly, ASN ensures oversight of the manufacture of the NPE that will be part of the primary and secondary systems of the nuclear steam supply system. In 2021, EDF continued with work to complete the installation, to make modifications to certain equipment and to draw up the various documents needed for operation. EDF also continued to analyse and remedy deviations, notably those affecting the MSS welds (see box below) as well as three MPS nozzles. EDF implemented a programme of additional inspections as part of the quality review requested by ASN owing to significant shortcomings in the monitoring of its contractors. EDF also deployed its equipment conservation and maintenance strategy and drew up the equipment requalification test programme in preparation for commissioning of the reactor. 3.3 Assessment of design, construction, start-up tests and preparation for operation of the Flamanville EPR reactor The examinations in progress ASN considers that the design of the Flamanville EPR reactor should be able to achieve the ambitious safety objectives set for the third generation reactors. It should also lead to a significant reduction in the probability of core melt and radioactive releases in the event of an accident, by comparison with the second generation reactors. The EPR reactor design in particular includes systems for managing severe accidents and is able to withstand extreme external hazards. This design only required very minor changes to take account of the lessons learned from the accident at the Fukushima Daiichi NPP. In 2021, EDF continued with the examinations linked to the commissioning authorisation application. ASN notably obtained the opinion of the Environmental Authority. A number of important technical subjects are still being examined. This is in particular the case with the design of the primary system safety valves, I&C upgrades, the performance of the containment internal water tank filtration system, the RGEs that will be applicable as of commissioning and incorporation of the lessons learned from the commissioning of the first EPR reactors abroad, in particular the various anomalies found on the cores of the EPR reactors in Taishan (China), including the fuel clad perforations observed in 2021. NPE conformity assessment 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 2021, ASN continued to assess the con– formity of the NPE design of the main primary and secondary systems and, as in 2020, in particular checked the preparation for and performance of the repairs to the main steam lines subject to the break preclusion requirements. ASN also continued the analysis of the deviations which affected the post-weld heat treatment of the connection welds on the SGs and pressuriser components carried out in Framatome’s SaintMarcel plant, as well as on the MSS lines carried out on the Flamanville site. EDF and Framatome plan repair operations whenever possible or, failing which, justification that the conformity of the equipment is not compromised. In 2021, ASN also continued to assess the conformity of the main primary lines with the break preclusion requirements. WELDS ON LINES OF THE MAIN SECONDARY SYSTEMS OF THE FLAMANVILLE EPR REACTOR Major repairs are required on the welds on the lines of the MSS of the Flamanville EPR reactor. The majority of these welds are located on the main steam lines, and are subject to a “break preclusion” approach: they thus require 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. After examining these intervention means and the qualification of the processes in 2020, ASN inspected the production of these eight welds in 2021. Most of the other welds on the main steam lines which are to be repaired, of which there are about 50, are located in an environment with no access difficulties. In 2021, ASN continued to assess the conditions for their repair and to monitor the weld repair operations. EDF was attentive to ensuring that the number of repairs made at the same time is compatible with the organisation of worksite surveillance. This work should continue until the summer of 2022. At the same time, EDF analysed the quality of other welds, in particular those on the 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 it has received all the justifications from EDF. 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 2021 307 10 – THE EDF NUCLEAR POWER PLANTS 08 07 13 04 10 06 12 14 03 09 05 11 02 AP 01
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