The commissioning decision set several milestones requiring ASN approval during the reactor start-up operations: ∙before commissioning of the MPS and MSS, EDF transmitted a file to ASN notably listing the work and checks carried out on these systems by EDF. ASN examined this file and carried out an inspection; ∙before first divergence of the reactor, EDF transmitted a file to ASN presenting the results of the start-up tests and the conformity of the composition of the reactor core. ASN also examined this file and carried out a campaign of five unannounced inspections. In a resolution of 2 September 2024, ASN authorised EDF to carry out the first criticality search and first divergence of the reactor. In autumn 2024, EDF continued with the start-up tests, notably with core testing at nil power and then at 10% reactor nominal power, as well as a large number of tests on the non-nuclear part of the installation using steam (turbine in particular). ASN monitored these activities and also carried out several thematic inspections, as it does periodically for the other EDF reactors in operation. Since commissioning of the reactor, EDF has reported a large number of ESS, about third of which were rated level 1 on the INES scale. ASN is particularly vigilant with regard to the analysis of the root causes of these events and the steps taken by EDF to learn all relevant lessons and safeguard the upcoming start-up activities and the future operation of the reactor. The large number of events reported is notably linked to the learning curve followed by the staff in initial reactor operations and the transition from a construction culture to one of operation. The causes of the vast majority of the events are organisational and human, with few being linked to equipment failures. A large share of the events is also linked to human errors that were immediately detected, leading to rapid conformity of the installation. ASN considers that the measures taken by EDF following these findings are pertinent and appropriate for the difficulties encountered during this phase. International experience feedback ASN takes part in the forum of authorities overseeing the safety of EPR reactors around the world. It thus regularly meets the Finnish, Chinese and British safety regulators in order to benefit from their experience of start-up tests, preparation for operation and the actual working of the EPR reactors. ASN closely examines the OEF from EPR reactors in operation and regularly verifies that the lessons learned are taken into account by EDF at Flamanville. In particular, a number of phenomena linked to the physical behaviour of the core, observed at start-up of the first EPRs, were taken into account before commissioning. 5 Regulation and oversight of the EPR 2 reactors project EDF has started a programme to build EPR 2 type reactors in France. A first pair of reactors is planned for the Penly site in the Seine-Maritime département, a second on the Gravelines site in the Nord département and a third on the Bugey site in the Ain département. For the Penly site, a public debate was held from 27 October 2022 to 27 February 2023, following which at the end of June 2023, EDF submitted a BNI creation authorisation application to the Minister responsible for nuclear safety. The construction work required for siting of the reactors was authorised by a Decree of 3 June 2024. The construction of the nuclear island may only begin after issue of the creation authorisation. For the Gravelines site, a public debate was held from 17 September 2024 to 17 January 2025. EPR 2 reactors safety options The EPR 2 is a new PWR model, which aims to incorporate operating experience feedback from the design, construction and commissioning of the EPR reactors, as well as experience feedback from the operation of the existing reactors. In the same way as the EPR reactors, it aims to meet the general safety objectives for third- generation reactors. Furthermore, this reactor will integrate all the lessons learned from the Fukushima Daiichi NPP accident, as of the design stage. This more specifically entails reinforcing the design against external natural hazards and consolidating the independence of the installation and the site in an accident situation (with or without core melt) until such time as the off-site resources can intervene. ASN examined the Safety Options Dossier (DOS) for this reactor project, with the support of IRSN, taking account of the recommendations of Guide No. 22 on PWR design. In its opinion published on 16 July 2019, ASN considered that the general safety objectives, the baseline safety requirements and the main design options were on the whole satisfactory and, in its opinion and in a supplementary letter sent to EDF in July 2021, identified the subjects to be considered in greater detail for a future BNI DAC. Technical reviews carried out in 2024 As set out in Article L. 592-29 of the Environment Code, the Minister responsible for nuclear safety instructed ASN to carry out the technical review of the creation authorisation application for the two EPR 2 reactors on the Penly site. This review is currently in progress. It follows on from the review of the EPR 2 reactors safety options. In 2024, ASN notably sent EDF its requests on the baseline requirements for taking account of internal hazards and the rating approach adopted to determine the requirements applicable to items performing a function necessary for the nuclear safety case. In addition to the technical review of the creation authorisation application file, ASN began a process to monitor the organisation put into place by EDF to manage its project. The purpose of this process is to check that the requirements relating to the protection of people and the environment to be met by the EPR 2 reactors are taken into account appropriately during the design and then construction phases of these reactors. With regard to the equipment to be installed as part of the Nuclear Steam Supply System (NSSS) for these reactors, ASN continued with the reviews to check their design and manufacture in 2024. Between 2021 and 2024, ASN issued a position statement on the design options of the main equipment intended for the MPS and MSS of these reactors, such as the reactor vessel and the SGs. ASN also approved the start of manufacturing of certain equipment, such as the reactor vessel and the SGs. In parallel with the evaluation of the design documentation, procurement of the components intended for this equipment is inspected, in particular the large forged items. The purpose of these inspections is to ensure that the manufacturing processes adopted offer sufficient guarantees that materials meeting the required quality level will be produced. ASN also started monitoring of the procurement chain for other safety-important items intended for the EPR 2 reactors, in order to evaluate the management of the manufacturing activities by the suppliers and EDF’s monitoring of them. ASN Report on the state of nuclear safety and radiation protection in France in 2024 323 01 The EDF Nuclear Power Plants 10 02 03 04 05 06 07 08 09 11 12 13 14 15 AP
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