ASN Report 2018

∙ ∙ a local emergency centre allowing emergency management of the nuclear site as a whole in the event of an extreme external hazard; ∙ ∙ a Nuclear Rapid Intervention Force (FARN) which, using mobile means external to the site, can intervene on a nuclear site in a pre-accident or accident situation; ∙ ∙ a range of corrective measures or improvements, notably the acquisition of additional communication and radiological protection means, the implementation of additional instrumentation, extensive consideration of internal and external hazard risks, improvement of the way in which emergency situations are taken into account. In addition to its requests, ASN issued a range of resolutions dated 21 January 2014 aiming to clarify certain design provisions for the “hardened safety core”, in particular the definition and justification of the extreme external natural hazard levels to be considered for the “hardened safety core”. Generally speaking, ASN’s requests are part of a continuing process to improve safety with regard to the targets set for the 3rd generation reactors and aim in addition to be able to cope with situations far beyond those normally considered for this type of installation. These requests are issued in application of the defence-in-depth approach and as such concern measures to prevent and mitigate the consequences of an accident, based on both additional fixed means and external mobile means planned for all the installations on a site beyond their initial design basis. Given the nature of the required work, the licensee must carry out studies for the design, construction and installation of new equipment, which first require lead times and then require a schedule to optimise their implementation on each NPP. In addition, when these major works are carried out on nuclear sites which are in service, it is also necessary to ensure that their performance does not degrade the safety of the nuclear power plants. So that the improvements needed as a result of the lessons learned from the Fukushima Daiichi NPP accident are made as rapidly as possible, while taking account of the constraints inherent in the engineering of these major works, EDF intends to implement these improvements in three phases. • Phase 1 (2012-2015) Deployment of temporary or mobile measures to enhance protection against the main situations of total loss of the heat sink or electrical power supplies. At the end of 2015, EDF had deployed the provisions of phase 1, which is now completed. More particularly, connection means were installed so that, in the event of an emergency, the mobile systems can be connected to provide water. In particular, the FARN, which is one of the main emergency management measures, was deployed. Since 31 December 2015, the FARN teams have the capacity for simultaneous intervention on all the reactors of a site in less than 24 hours (up to six reactors in the case of the Gravelines site). • Phase 2 (2015-2021) Deployment of certain final design and organisational means that are robust to extreme hazards, in order to deal with the main situations of total loss of the heat sink or of electrical power supplies beyond the baseline safety requirements in force. The most important measures are: ∙ ∙ installation of a large-capacity ultimate backup diesel- generator set, requiring the construction of a dedicated building; ∙ ∙ setting up of an ultimate water source; ∙ ∙ creation of an ultimate water make-up system for each reactor and each spent fuel pool; ∙ ∙ reinforcement of the earthquake resistance of the containment venting filter; ∙ ∙ construction on each site of a local emergency centre capable of withstanding extreme external hazards (functionally independent in an emergency situation). On the various sites, EDF has begun to implement a large part of the permanent measures recalled above, more particularly the construction of the ultimate back-up diesel generator sets. ASN is inspecting the performance of the work. Postponed commissioning of ultimate backup diesel-generator sets (DUS) In its resolutions of 26 June 2012, issued further to the conclusions of the stress tests performed in the wake of the Fukushima Daiichi NPP accident, ASN instructed EDF to deploy an additional means of electrical power supply before 31 December 2018, so that if the other on-site and off-site electricity sources are lost, the systems and components belonging to the “hardened safety core” can be supplied with power. In response to these requirements, EDF began the construction of ultimate backup diesel-generator sets (DUS). EDF informed ASN that for 54 reactors, it was impossible to meet the 31 December 2018 deadline for deployment of these ultimate back-up diesel generating sets. ASN considered that the difficulties encountered by EDF were justified and that some of them still persist. They are notably the result of the scale and complexity of the operations and the particularities of certain sites. ASN modified the commissioning schedule for the ultimate back-up diesel generating sets owing to the technical difficulties encountered by EDF. In parallel with this rescheduling, with the deadline now being set at 31 December 2020, ASN issued binding requirements for an increase in the robustness of the existing electricity sources. ASN report on the state of nuclear safety and radiation protection in France in 2018  305 10 – EDF NUCLEAR POWER PLANTS 10