EDF / 2019 Universal registration document

1. The Group, its strategy and activities Description of the Group’s activities

Progress of on-site implementation As of the end of December 2019, electrical and mechanical assemblies were over 98% complete; the remaining activity will be carried out as and when system performance testing is conducted. 2019 was marked by: the remainder of the initial electrical and mechanical assemblies being ■ completed; the satisfactory completion of phase 1 Hot Tests (EAC1) in early 2019, with ■ completion of almost 95% of the planned test programme, the start of phase 2 Hot Tests (EAC2) on 21 September achieving the stable threshold (303° C, 154bar) on 18 October with completion of the tests on 17 February 2020; commissioning of the Controlled Access Area and the Enhanced Protection Area; ■ finishing and handover of a number of buildings to operational teams. For ■ instance, responsibility for the release building, fuel intake building, and backup diesel buildings has now been transferred to the operator, demonstrating the high level of finishing of these installations. By the end of December 2019, tests were 61% complete and finishings were 79% complete. Equipment manufacturing and quality By the end of 2019, almost all the equipment for the nuclear section and the conventional island, had been delivered and assembled on site. The situation as regards the quality of equipment manufactured by Framatome for the primary system is described in the following paragraphs. Reactor vessel In the first half of 2017 the ASN examined “higher-than expected” carbon levels in the vessel head and bottom on the basis of documentation submitted by Framatome, under the supervision of EDF. Based on the opinion of a group of ASN-appointed experts, the ASN issued an opinion on 11 October 2017 concluding that the mechanical properties of the vessel head and bottom head were adequate for their uses, including in the event of an accident. On 9 October 2018, the ASN authorised: the commissioning of the vessel bottom, subject to functional checks; ■ the commissioning of the vessel head, for a limited operating life until 2024 ■ unless the technical feasibility of checks comparable to the vessel bottom checks can be demonstrated. EDF is in the process of carrying out a project to develop inspection of the vessel head during service, so that a proposal can be made to the ASN to keep the existing head if this type of operation is industrially feasible, as an alternative to ending use of the existing head by the end of 2024, as requested by the ASN. EDF has nevertheless asked Framatome to begin work on the supply of a new equipped vessel head, in the event of a need to replace it in 2024. The costs incurred for the manufacture of a replacement vessel head are not included in the target construction cost due to the fact that they would be incurred, if applicable, after commissioning. Furthermore, EDF SA has initiated arbitration proceedings against AREVA SA on this matter. Break preclusion and quality deviations in the welds of the main secondary system On 30 November 2017, EDF declared a significant event to the ASN regarding the detection of a quality deviation in the welding of the secondary system that conducts the steam from the steam generators to the turbine of the Flamanville 3 EPR. The circuit that transfers the steam from the steam generators to the turbine of the Flamanville 3 EPR (main steam line) was designed and manufactured according to

the “break preclusion concept”. This approach consists in strengthening requirements for design, manufacture and monitoring in service. These strengthened requirements, requested by EDF, also involve a “high quality” requirement in the building of these systems  (1) . Although these requirements were applied during the design phase, they were not properly incorporated into the welding work. Failure to meet these requirements does not necessarily entail non-compliance with the nuclear pressure equipment regulations. After 21 March 2018, during the initial comprehensive inspection, EDF also identified quality deviations on the welding of the pipes of the main secondary system of the Flamanville EPR. The initial comprehensive inspection, is a regulatory requirement prior to the plant commissioning, which consists, in particular, in examining the welds of the primary and secondary systems. It gives rise to an initial benchmark report on the state of plant before it begins operation. In accordance with industrial procedures, the welds had been inspected by the consortium of contractors in charge of manufacturing the system. Each weld had been declared compliant by the consortium just as they were being completed. On 10 April 2018  (2) , EDF notified the ASN of a significant event relating to the detection of deviations in the inspection of these welds (part of the main secondary system was already subject to a deviation with respect to the correct application of “break preclusion” requirements). EDF therefore began a further inspection during the second quarter of 2018 of all welds concerned in the main secondary system. For eight of these, known as reactor containment building penetration welds, on 3 December 2018 EDF provided a specific justification file to the ASN. On 9 April 2019, the ASN convened the permanent experts’ group for pressurised nuclear installations (GP ESPN) as part of its investigation of the discrepancies impacting welds on the main steam pipework for break preclusion at the Flamanville EPR. In its consultative opinion, the permanent group recommended to the ASN that if EDF could not abandon all or part of break preclusion, it should carry out compliance work on these penetration welds. This consultative opinion forms part of the decision-making procedure within the remit of the ASN College. The decision was handed down on 19 June. In a letter dated 7 June 2019, EDF sought the ASN’s opinion on the possibility of repairing these welds after commissioning of the reactor, taking the view that commissioning of the installation in its current state presented no risks to safety (since the integrity of these lines had been demonstrated), and that post-start-up upgrading would allow the upgrading method used to be developed and optimised. In a letter dated 19 June 2019, the Nuclear Safety Authority (ASN) asked EDF to rework the eight penetration welds on the Flamanville EPR reactor containment building that deviated from the break preclusion reference document.  (3) EDF therefore assessed three reworking scenarios  (4) . This work led to discussions with ASN; on 4 October, the latter sent EDF a letter discussing the technical acceptability of these three scenarios. EDF’s preferred scenario for reworking the penetration welds is the use of remotely controlled welding robots, designed to conduct high-precision operations within the pipework in question. This technology has been developed for the fleet in operation, and must be qualified for reworking penetration welds. The aim is for this scenario to be qualified and approved by the ASN no later than the end of 2020, at which time EDF would be able to commence works. A second scenario, involving extraction and upgrading in auxiliary backup buildings, is presently being kept as an alternative solution.

(2) See EDF press release of 10 April 2018 “EDF has detected quality deviations on certain welds of the main secondary system of the Flamanville EPR and has begun additional controls”. (3) See EDF’s press release of 20 June 2019: “Flamanville EPR: EDF is reviewing decision from French Nuclear Safety Authority”. (4) See EDF’s press release of 26 July 2019. (1) Given that these requirements were stated, the potential for pipes rupturing did not have to be considered during the safety demonstration. This proves, with a high degree of confidence, that accidents are physically impossible or extremely unlikely and that their consequences are limited to acceptable economic conditions.

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EDF | Universal registration document 2019