In this respect, the project must undergo an environmental evaluation. This is a new regulatory procedure required by an amendment to the French Environmental Code. The ASN referred the matter to the Environmental Authority in early September 2021, which issued its opinion on 22 December 2021. It recommends that the application, prepared on the basis of an environmental impact study be completed on several points and, in particular, that it addresses the impacts of the prior construction phases of the Flamanville EPR and the Cotentin Maine very high voltage power line. These recommendations were discussed with the ASN in 2022. A brief was drafted in response by EDF and sent to the ASN in March 2022, then expanded at the request of the ASN in November 2022.
Since the commissioning request dossier includes EDF’s impact study, the opinion of the environmental authority and EDF’s brief in response will be the subject of a public consultation scheduled in May-June 2023. The ASN decision to authorise commissioning is expected in December 2023.
On 8 October 2020, pursuant to the French Environmental Code, the ASN authorised the arrival of nuclear fuel at the Flamanville site, after an on-site inspection on 18 and 19 August 2020 and after public consultation on the draft authorisation from 31 August to 21 September 2020. The 245 fuel assemblies necessary for loading (241 assemblies for the first core, 4 assemblies for the reserve) were received at the end of the first half of 2021. The first regulatory fuel inspection (Euratom) was performed at the end of August 2021. See below “Lessons learned from Taishan”.
The commissioning deadline specified in the Authorisation Decree was extended until 11 April 2024(1), to take into account the weld repairs in the main secondary circuit (see below).
EDF received this operating authorisation on 30 August 2021, pursuant to the Energy Code, in an order issued by the Minister for the Ecological Transition.
The year 2022 was marked by the following achievements:
Also of note:
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 the supervision of EDF. Based on the opinion of a group of ASN- appointed experts, the ASN concluded that the mechanical properties of the vessel head and bottom were adequate for their uses, including in the event of an accident (3). On 9 October 2018, the ASN authorised the commissioning of the vessel bottom, subject to functional checks and the commissioning of the vessel head, by limiting the lifespan to end 2024.
The project is preparing the replacement of the reactor vessel head, scheduled after the installation has been commissioned. The manufacture of a new vessel head is underway in Framatome facilities, with site delivery scheduled in 2024. Therefore, the costs incurred for the manufacture of a replacement vessel head are not included in the target construction cost.
In December 2022, Framatome issued a request to postpone the date for replacement of the vessel head until the end of the first operating cycle (in the second half of 2025). The ASN will examine this request and issue a ruling on next steps.
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 (VVP pipework circuit).
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(4). 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, 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 (5). In accordance with industrial procedures, the welds had been checked by the consortium of contractors in charge of manufacturing the system and each one had been declared compliant as the work was done. EDF began a further inspection during the second quarter of 2018 of all welds concerned in the main secondary system.
On 19 June 2019 the ASN asked EDF to rework eight welds on VVP main steam circuit pipework (known as reactor containment building penetration welds), prior to commissioning.
EDF’s proposal for reworking the penetration welds is the use of remotely controlled robots, designed to conduct high-precision operations within the pipework in question. The ASN approved this process on 19 March 2021. All eight of these penetration welds were upgraded in 2021. In late 2022, Stress-Relieving Heat Treatment (SRHT) and final inspection of the eight welds were completed.
Four penetration welds (on the steam generator water supply lines, “ARE”) were also the subject of upgrades. As of the end of 2022, these four welds had been repaired by means of remote controlled robots (6); SRHT and final inspections had also been completed.
The penetration weld upgrading works have now been completed. Works to “re- close” the ARE and VVP lines (reinstalling the sections removed to work on the penetration welds) are now underway.
The technical investigation into reworking the welds located on the main secondary circuit with quality shortfalls and/or not complying with the requirements of the break preclusion reference is ongoing. The upgrading works that were begun in summer 2020 and completed at the end of 2022 concerned 45 VVP welds and 41 ARE welds. Non-destructive testing and SRHT are underway.
SRHT is a manufacturing operation that, in addition to giving the welded joint the expected mechanical properties, aims to reduce the residual stresses that develop within a material during a welding operation. SRHT is performed by heating the welded joint for a determined period of time at a temperature of about 600°C (+/-15°C).
(1) In a Decree dated 25 March 2020.
(2) World Association of Nuclear operators.
(3) Opinion dated 11 October 2017.
(4) 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.
(5) 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.
(6) This process is an adaptation of the one used for VVP penetration repairs.
