Universal Registration Document 2020

1. The Group, its strategy and activities

    Progress of on-site implementation

2020 was marked by:

  • the completion of phase 2 of the Hot Tests (EAC2) from 21 September 2019 to
    17 February 2020;
  • completion of the rest of the open vessel functional tests (EFCOs) from 23 May to 25 June 2020;
  • completion of instrumentation & control outages in June and July 2020 and the beginning of electricity outages in July;
  • the launch of upgrading of the first seven welds on the Main Secondary Circuit, five of which were completed during the year;
  • opening of the Enhanced Protection Area to pedestrians between Flamanville 1&2 and Flamanville 3, on 9 September 2020;
  • completion of all points required for fuel delivery;
  • production of a “fire” action plan;
  • preparatory work for the qualification of remotely-operated robots used for penetration weld repairs;
  • management of the Covid-19 health crisis in spring 2020, on site and remotely during lockdown. Work was suspended during the first lockdown in March 2020, except for site watch and equipment conservation. Consequently, the accounting procedure to capitalise the interim interest on the project was suspended between 15 March and 1 July 2020.
Quality equipment manufacturing

By the end of 2020, almost all the equipment for the nuclear section and the conventional island, had been delivered and assembled on site.

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, by limiting the lifespan to 2024, unless the technical feasibility of checks is proven to be similar to the vessel bottom.

In 2020, EDF halted the project to develop inspection of the vessel head during service, the aim of which was to make it possible for a proposal to be made to the ASN to keep the existing head, subject to the industrial feasibility of this type of operation. The project is now focused on replacing the vessel head by the end of 2024, the supply of a new equipped vessel head having been ordered from Framatome.

Consequently, the costs incurred for the manufacture of a replacement vessel head are not included in the target construction cost. Furthermore, arbitration proceedings have been engaged with respect to this matter by EDF, AREVA SA, AREVA NP, and Framatome.

Break preclusion and quality deviations in the welds of the main secondary circuit

On 30 November 2017, EDF declared a significant event to the Nuclear safety authority regarding the detection of a quality deviation in the welding in the main secondary pipes that transfer the steam from steam generators to the turbine at Flamanville 3 EPR.

This system 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.

On 10 April 2018(2), EDF notified the ASN of a significant event relating to the detection, during the initial comprehensive inspection, of deviations in the inspection of the welding of the pipes of the main secondary circuit of the Flamanville EPR(3) (part of the main secondary circuit was already subject to a deviation with respect to the correct application of “break preclusion” requirements). 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. EDF therefore began a further inspection during the second quarter of 2018 of all welds concerned in the main secondary circuit. For eight of these, known as reactor containment building penetration welds, on 3 December 2018 EDF suggested providing a specific “as-is” design calculation file to the ASN.

On 9 and 10 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.

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, before commissioning, the eight penetration welds on the Flamanville EPR reactor containment building that deviated from the break preclusion reference document(4). EDF therefore assessed three reworking scenarios(5).

This work led to discussions with ASN; on 4 October 2019, the latter sent EDF a letter discussing the technical acceptability of these three scenarios. The scenario for VVP(6) penetration weld repairs finally selected by EDF involves the use of remotely controlled 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. In view of this strategy for reworking the penetration welds, in its meeting on 8 October 2019, EDF’s Board of Directors approved the continuation of works at the Flamanville EPR site.

In total, at this stage, repairs concern some one hundred welds on the
Main Secondary Circuit (Circuit Secondaire Principal, CSP), on the steam generator water supply lines (ARE), and on the steam generator steam removal lines (VVP). At this stage, repairing the penetration welds is one of the key challenges on the critical pathway. However, repair work on other welds and other activities underway on the worksite are also creating additional risk to the schedule and the target cost on completion for the reactor.

(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.

(2) See EDF press release of 10 April 2018 “EDF has detected quality deviations on certain welds of the main secondary circuit of the Flamanville EPR and has begun additional controls”.

(3) 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.

(4) See EDF’s press release of 20 June 2019: ”Flamanville EPR: EDF notes the French Nuclear Safety Authority’s decision”.

(5) See EDF’s press release of 26 July 2019.

(6) VVP: steam discharge pipework circuit.