ASN Report 2017

34 ASN report on the state of nuclear safety and radiation protection in France in 2017 Nuclear Power Plants (NPPs) operated by EDF are at the heart of the nuclear industry in France. The 58 French reactors are technically very similar and thus form a standardised fleet. ASN imposes stringent requirements on these facilities, the regulation and oversight of which mobilises nearly 200 inspectors and as many IRSN experts, on a daily basis. ASN has developed a proportionate and integrated approach to regulation that covers not only the design of new installations, their construction, the operation of existing reactors, modifications, integration of feedback, but also social, human and organisational factors, radiation protection, environmental protection, occupational safety and the application of labour legislation. Nuclear reactors operated by EDF 2017 was marked by four significant events rated level 2 on the INES scale, each of which affected several reactors. Of particular note is the event concerning the resistance deficiency found in the Donzère-Mondragon canal embankment protecting the Tricastin NPP. In September 2017, this event led ASN to require that EDF temporarily shut down the four reactors of the NPP as rapidly as possible. In December 2017, further to the investigations and repairs carried out by EDF, ASN considered that the condition of the Donzère-Mondragon canal embankment allowed restart of the reactors of the Tricastin nuclear power plant. The three other events rated level 2 on the INES scale involved the availability of certain systems important for the safety of the installations, such as electrical systems or the heat sink. Some of the defects identified are linked to equipment design, others to its assembly or maintenance. These events highlight the difficulties experienced by EDF in ensuring the conformity of its facilities and maintaining this over time. These difficulties also underline the need to continue with the design reviews in progress: these are bearing fruit and revealing anomalies, some of which have been present since the reactors were built. Detection of these deviations also indicates inadequacies in the maintenance programmes of certain equipment items. ASN also considers that EDF must reinforce its actions and decision-making processes in dealing with deviations. Non-compliance with general operating rules is still the cause of a considerable number of significant events. These events also reveal flaws in the oversight of the drafting processes for the general operating rules and the preventive maintenance programmes. ASN considers that the quality of maintenance work could still be improved, as the number of maintenance work quality defects found remains high. The inspections carried out by ASN on deployment of the modifications resulting from the third periodic safety review of the 1,300 MWe reactors show that EDF experiences difficulties in ensuring consistency between the physical state of the installations at the time of reactor restart and the state considered in the general operating rules. ASN asked EDF to regularise the situation and learn the necessary lessons from this deployment in preparation for the fourth periodic safety review of the 900 MWe reactors. The organisation in place on the sites for managing skills, qualifications and training is on the whole satisfactory. EDF has allocated major investments to hiring and training, in order to anticipate the renewal of skills as a result of staff retirements. In a context of a rising volume of maintenance work, the collective dosimetry on all the reactors fell in 2017. On no occasion was the annual regulation limit for whole body external dosimetry (20 mSv) exceeded. ASN considers that EDF’s organisation for management ofNPPdetrimental effects and impacts on the environment is satisfactory onmost sites. Operational management of radioactive and conventional waste on the worksites could on thewhole be improved across the NPPs. The ASN assessments of each NPP are detailed in chapter 8 of the report. Certain sites stand out positively: ཛྷ ཛྷ in the field of nuclear safety: Fessenheim; ཛྷ ཛྷ in the field of environmental protection: Fessenheim; ཛྷ ཛྷ in the field of radiation protection: Chinon and, to a lesser extent, Civaux. Other sites are on the contrary under- performing with respect to at least one of these three topics: ཛྷ ཛྷ in the field of nuclear safety: Belleville- sur-Loire and, to a lesser extent, Gravelines and Chooz; 12 EDF Nuclear Power Plants Significant events and outlook