After examining the objectives proposed by EDF, with the support of IRSN, and following consultation of its Advisory Committees, 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. 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 2021, EDF had carried out or initiated seven 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. Involving the public at each step For the purposes of this periodic safety review, ASN has been involving the public since 2016 in the drafting of its position statement regarding the objectives proposed by EDF. This approach continued in 2018, under the aegis of the High Com– mittee for Transparency and Information on Nuclear Safety (HCTISN), in the form of a consultation on the measures planned by EDF to meet these objectives. At the end of 2020, ASN also consulted the public on its draft resolution specifying the conditions for continued operation of these reactors. Pursuant to the law, a public inquiry will then be held, reactor by reactor, after submission of the periodic safety review concluding report for each reactor. ASN will thus issue a position statement on the continued operation of Tricastin NPP reactor 1 after this public inquiry is held in 2022. The 1,300 MWe reactors The third periodic safety review At the beginning of 2015, ASN issued a position statement on the generic aspects of the continued operation of the 1,300 MWe reactors beyond 30 years of operation. On this occasion, ASN underlined the importance of the modifications made by EDF following their third periodic safety review. Within the framework of this review, EDF is notably deploying material and operational modifications in order to mitigate the consequences of an SG tube break accident, to prevent the occurrence of severe accidents with early loss of containment, and to reduce the risk of uncovering the fuel assemblies present in the spent fuel pool. With regard to hazards, EDF is modifying its installations in order to guarantee operation of the equipment needed for the safety of these reactors in the event of a heatwave, to protect the equipment important for safety against projectiles created by strong winds and to prevent the risks of explosion further to an earthquake. To help conclude the generic phase of this review, ASN issued additional requests in 2021 applicable to all the 1,300 MWe reactors, with the aim of reinforcing their safety. In 2021, Belleville-sur-Loire NPP reactor 1 and Cattenom NPP reactor 3 underwent their third ten-yearly outage. The third tenyearly outages for the other 1,300 MWe reactors will run until 2024. The fourth periodic safety review In July 2017, EDF presented a file giving the orientations en– visaged for the generic phase of the fourth periodic safety review of the 1,300 MWe reactors. In 2019, ASN issued a position statement on these orientations, after involvement of the public and consultation of the GPR on 22 May 2019. ASN considers that the general objectives set by EDF for this review are acceptable in principle. They notably aim to do away with population protection measures for design-basis accidents, and –for severe accidents– to tend more towards population protection measures that are limited in both scope and duration. With regard to the safety of the spent fuel pool, ASN asked EDF to set an objective of no uncovering of the assemblies and to eventually return the installation to and permanently maintain it in a state without pool water boiling. In 2021, ASN continued with the expert assessments for the generic phase of this periodic safety review. They more specifically concerned the methods to be used during this review for the study of certain accidents and the assessment of the robustness of the installations to hazards. EDF has also started the studies needed to update the regulation reference files for the main primary and IMPLEMENTATION OF A “HARDENED SAFETY CORE” OF MATERIAL AND ORGANISATIONAL MEASURES FOR THE MANAGEMENT OF EXTREME SITUATIONS The steps taken further to the lessons learned from the Fukushima Daiichi NPP accident, in particular the DUS and ultimate water sources, are supplemented during the periodic safety reviews by implementation of a “hardened safety core” of material and organisational provisions. In the event of an extreme situation, the purpose of this “hardened safety core” is: ཛྷ to prevent an accident with fuel melt, or limit its progression; ཛྷ to limit large-scale radioactive releases; ཛྷ to enable the licensee to carry out its emergency management duties. The most important measures are: ཛྷ the addition of a new makeup pump to the primary system; ཛྷ the addition of a new means of injecting borated water into the primary system when it is at high pressure; ཛྷ the completion of connection by fixed backup water supply systems for the SGs and ultimate water make-up for the fuel storage pool; ཛྷ the addition of an extra fuel pool cooling system, partly reliant on mobile means; ཛྷ the installation of an ultimate containment cooling system, partly reliant on mobile means, to prevent opening of the filtered vent on this containment in the event of a severe accident; ཛྷ the adoption of measures to stabilise the corium on the basemat, in the event of an accident with core melt and reactor vessel melt-through; ཛྷ the installation of an ultimate instrumentation and control system and the necessary instrumentation. Since 2019, these provisions have been deployed during the fourth periodic safety reviews of the 900 MWe reactors. More particularly, the containment ultimate cooling system, the system designed to stabilise the corium on the basemat, in the event of an accident with core melt, and the additional fuel pool cooling system, are installed as of the fourth ten-yearly outages. ASN Report on the state of nuclear safety and radiation protection in France in 2021 305 10 – THE EDF NUCLEAR POWER PLANTS 08 07 13 04 10 06 12 14 03 09 05 11 02 AP 01
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