∙ The safety reassessment: this second step aims to improve the level of safety, notably taking account of the experience acquired during operation, changing knowledge, the requirements applicable to the more recent installations and international best practices. Following these reassessment studies, EDF identifies the changes it intends to make to its facilities in order to enhance safety. The review process for the EDF nuclear power reactors In order to benefit from the standardisation of its nuclear power reactors, EDF first of all implements a generic studies programme for a given type of reactor (900MWe, 1,300MWe or 1,450MWe reactors). The results of this programme are then applied to each nuclear power reactor on the occasion of its periodic safety review. EDF more particularly carries out a large part of the checks and modifications related to the periodic safety reviews during the ten-yearly inspections of its reactors. Following this periodic safety review, and in accordance with the provisions of Article L. 593-19 of the Environment Code, the licensee sends ASN a periodic safety review concluding report. In this report, the licensee states its position on the conformity of its facility and details the modifications made to remedy deviations observed or to improve the safety of the facility and, as necessary, specifies the additional improvements that it will be making. ASN analysis ASN examines the periodic safety reviews in several stages. It first of all issues a position statement on the objectives of the review and the guidelines of the generic programmes to verify the state of the facility and the safety reassessment proposed by EDF, after obtaining the opinion of the Advisory Committees of Experts (GPEs). On this basis, EDF carries out safety reassessment studies and defines the modifications to be made. ASN then issues a position statement on the results of these studies and on these modifications, after again consulting the GPEs. This position statement closes the generic phase of the periodic safety review, common to all the reactors. This generic review does not take account of any specific individual aspects and ASN gives a ruling on the suitability of each nuclear power reactor for continued operation, notably on the basis of the results of the conformity checks and the assessment made in the periodic safety review concluding report for the reactor submitted by EDF. Following examination of the periodic safety review concluding report for each reactor, ASN communicates its analysis to the Ministry responsible for nuclear safety. It can issue new requirements governing its continued operation. A public inquiry is held concerning the concluding report for the periodic safety reviews beyond the 35th year of operation of a nuclear power reactor. Five years after submission of the review concluding report, the licensee sends ASN an interim report on the implementation of the requirements stipulated by the review, as a result of which ASN may add to these requirements. 3.3 ONGOING PERIODIC SAFETY REVIEWS IN THE NUCLEAR POWER PLANTS The 900 MWe reactors The fourth periodic safety review EDF’s 32 reactors of 900 MWe in operation were commissioned between 1978 and 1987. The first ones have reached the milestone of their fourth periodic safety review. This fourth periodic safety review comprises particular challenges: ∙ Some items of equipment are reaching their design-basis lifetime. The studies concerning the conformity of the installations and the management of equipment ageing therefore need to be reviewed to take account of the degradation mechanisms actually observed and the maintenance and replacement strategies implemented by EDF. ∙ The safety reassessment of these reactors and the resulting improvements must be carried out in the light of the safety objectives of the new-generation reactors, such as the EPR, the design of which meets significantly reinforced safety requirements. The modifications associated with this periodic safety review incorporate those linked to deployment of the “hardened safety core”. ASN’s position statement on the generic phase of the periodic safety review In 2013, EDF sent ASN its proposed objectives for this periodic safety review, in other words, the level of safety to be achieved for continued operation of the reactors. After examining the objectives proposed by EDF, with the support of IRSN, and following consultation of its GPEs, ASN released a position statement on these objectives and issued additional requests in April 2016. EDF supplemented its programme of work and in 2018 presented ASN with the measures it envisages taking in response to these requests. In 2020, with the support of IRSN, ASN finalised its examination of the generic studies linked to this review. At the beginning of 2021, ASN issued a position statement on the conditions for continued operation of the reactors. ASN considered that the measures planned by EDF combined with those prescribed by itself open up the prospect of continued operation of these reactors for the ten years following their fourth periodic safety review. In October 2023, EDF asked ASN for postponement of the deadlines for some of the requirements in the resolution adopted in February 2021. Unexpected technical issues during implementation of some of the requirements, changes in the refuelling outages schedule, notably linked to the discovery of SC on the auxiliary lines, unexpected long-duration shutdowns or the needs of the electricity grid during the winter period, as well as a logjam with other periodic safety reviews, creating pressure on its engineering capacity, led EDF to revise its ability to carry out the activities needed to comply with the requirements, on time. ASN considered EDF’s request to be acceptable in the light of the explanations provided. Deployment of the periodic safety review on the site EDF carried out the first of the fourth ten-yearly outages in 2019 (Tricastin NPP reactor 1). At the end of 2023, EDF had carried out or initiated 17 of these ten-yearly outages. These outages are a major step in the fourth periodic safety reviews. During these outages, EDF carries out the required inspections and deploys most of the safety improvements associated with the review. In 2023, the public inquiries were held relating to the fourth periodic safety reviews of Bugey NPP reactors 2, 4 and 6 and of the Dampierre-en-Burly NPP. Finally, on 29 June 2023, ASN issued its position statement on the continued operation of Tricastin NPP reactor 1. This is ASN’s first position statement on a reactor in the light of the conclusions of its fourth periodic safety review. 314 ASN Report on the state of nuclear safety and radiation protection in France in 2023 • 10 • The EDF Nuclear Power Plants
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