In late 2020, Framatome reported to the ASN a deviation in the SRHT process historically used on the welds of the main secondary circuit of Flamanville 3. Framatome the developed an “optimised” process to ensure compliance with the required temperature range.
The demonstration of the qualification of the SRHT processes must be approved by the ASN on the basis of supporting documentation. In late 2021, the ASN approved this qualification demonstration of optimised SRHT processes for VVP penetration welds, as well as for “simple geometry” non-penetration welds. The rest of the procedures were validated in 2022.
In 2022, a number of anomalies were encountered during “complex geometry” SRHT, most relating to operational requirements for implementation. New studies and tests had to be carried out; these required research and development and new iterations to validate how these SRHT would be carried out on the 15 equipments in question. As of the end of 2022, these SRHT were in progress on the work site.
The latest technical issues being examined by the ASN were closed in 2022; the review of the examinations carried out since 2019 was presented to the GP ESPN (1) at its meeting on 30 November 2022. In conclusion, the group took the view that EDF had responded to its 2019 meeting recommendations and that the situation had been corrected. The ASN concurred, and concluded that subject to the proper completion of the final work site activities (SRHT, NDT (2)), compliance with the break preclusion reference of VVP pipework would be demonstrated.
In a separate development, on 2 March 2021 EDF declared a significant event to ASN. This concerned the incomplete consideration of the 2006 study referential in respect of the implantation of three nozzles (3) on the main primary circuit.
On 21 June 2021, EDF submitted a dossier to the ASN stating that it had chosen the solution consisting of installing a “retaining clamp” on each of the nozzles concerned. In a letter dated 8 October 2021, the ASN indicated that it had no objection in principle to this solution. The design of the retaining clamps was also examined by IRSN, which handed down a positive opinion on 30 November 2022. The retaining clamps were manufactured between mid-2021 and mid-2022 and are currently being installed around the nozzles.
The ASN also stressed the need to demonstrate the quality of welds with respect to the requirements applicable to pressurised nuclear equipment. The X-ray inspections carried out between August and October 2021 confirmed that these welds are of good quality. They have been supplemented by ultrasound inspections in the first half of 2022; these also proved to be satisfactory. IRSN is finalising the examination of these inspections; this should be complete in the first half of 2023.
The Flamanville EPR is equipped with a recirculation system for the water in the main primary circuit in the event of a pipe breach. In the event of an accident, this system recovers water from the bottom of the reactor building and recirculates it into the tank in order to cool the fuel assemblies.
A problem was detected during a “full-loop” test in the summer of 2021. The debris contained in the recirculated water were not effectively filtered by the filters located at the bottom of the reactor building.
Following these tests, EDF replaced these filters in September 2022 and fitted them with a finer filter mesh. EDF also decided to reduce the potential quantities of debris with proven filter clogging potential. This work to reduce potential debris has been almost completed (finalisation is expected in the first quarter of 2023).
As of the end of January 2023 the full dossier, taking into account the results of the most recent tests in late 2022, has been supplied to the ASN with a view to completion of the final examination of this technical dossier. The findings of this examination are expected by the end of the first half of 2023.
Following the discovery of corrosion on the pressuriser valves (PSRV valves) of the Olkiluoto EPR (Finland), EDF and Framatome carried out inspections on this equipment and also discovered traces of corrosion on the valves of the Flamanville EPR. EDF and Framatome have decided to take it into account and to modify the material used for certain valve pilot components. Several corrosion resistance tests were performed in order to select the best material. These components have been fabricated and are now installed in the reactor building. In addition to dealing with this difficulty, the ASN is continuing to investigate the operation and reliability of the pressuriser valves. The findings of this examination are expected before the end of the first half of 2023.
EDF has analysed the potential impact of the technical issues encountered on reactor 1 of the Taishan plant (see section 1.4.5.3.6.1 “Activities in China”) on the commissioning of the Flamanville EPR (5). Inspections carried out on the relevant fuel assemblies showed mechanical wear of certain assembly components.
EDF plans to replace the potentially affected fuel assemblies at the edge of the core by 64 new fuel assemblies that have undergone heat treatment to mitigate the risk of wear to a significant degree, before start-up. The IRSN issued a favourable opinion with no reservations in respect of the dossier submitted by EDF. Examination of this solution by the ASN is underway.
In its press release dated 16 December 2022 (6), EDF adjusted the project schedule and completion cost. Fuel loading was postponed from the second quarter of 2023 to the first quarter of 2024. The estimated completion cost was revised from €12.7 billion to €13.2 billion (7) excluding interim interest. This revision of the schedule is due in particular to additional studies required to determine the new procedure for implementing the SRHT process.
The costs of post-commissioning modifications are not included in the construction cost of the project.
For details of investments for the Flamanville 3 EPR, see note 10.6 in the appendices to the 2022 consolidated financial statements.
The risk relating to the schedule and the completion cost remains high, especially in the event of new technical issues arising. In addition, work site delays entail a risk of equipment and materials ageing. See section 2.2.4 “Risks related to operational performance” – “4A – Management of large and complex industrial projects (including EPR projects)”.
The work undertaken by EDF and Framatome on the New Model EPR project led to the finalising in 2017 of the technical configuration of a model named EPR2 which could ultimately expand the French nuclear offer in France and for export. EPR2 is an optimised version of the EPR, following on from the EPR in industrial terms, whilst integrating feedback from EPR work sites and power plants currently in operation.
Following the French government’s request that EDF should, together with the nuclear industry, prepare a full dossier on a renewal programme for nuclear facilities in France by mid-2021, in May 2021 EDF supplied it with a “Proposal by EDF and the nuclear industry for a programme of new reactors in France”. The programme calls for building three pairs of EPR2s successively at Penly, Gravelines and a third riverside site in the Auvergne Rhône Alpes region (Bugey or Tricastin), while continuing the feasibility analysis at other nuclear sites.
(1) Permanent expert group for pressurised nuclear installations (GP ESPN).
(2) NDT = non-destructive testing.
(3) A nozzle allows to connect auxiliary circuits to the primary circuit.
(4) SIS = Safety injection circuit (used to add pressurised borated water to the reactor’s primary circuit in the event of an accident that causes a major breach to this circuit). EVU = Ultimate heat removal system for the reactor building in the event of a severe accident (with core meltdown).
(5) See EDF’s press release of 12 January 2022 “Update on the Flamanville EPR”.
(6) See press release dated 16 December 2022 “Update on the Flamanville EPR”.
(7) In 2015 euros.
