internal flooding risks, notably by considering several possible water flow routes, and has defined additional provisions to mitigate the risks. In 2022, ASN examined the new methodology proposed and asked EDF for adjustments. Seismic risks The inspection programmes implemented by EDF lead it to regularly report significant safety events owing to the lack of seismic resistance of certain equipment. These events are the result of targeted inspections gradually being deployed by EDF. These non-compliances can have serious consequences in the event of an earthquake and they are thus systematically analysed. On 11 November 2019, an earthquake occurred in the municipality of Le Teil (Ardèche département). It led EDF to implement the operating procedure required in the event of an earthquake on the Cruas-Meysse NPP. This was because the seismic motion detected on this site reached the level requiring shutdown of the reactors so that checks could be carried out. An inspection programme was then defined and carried out before the reactors were restarted. In November 2019, ASN asked EDF to determine whether this earthquake should lead to a revision of the seismic levels to be adopted for protection of the Tricastin and CruasMeysse NPP sites. After field investigations, EDF defined a new design response spectrum for the Cruas-Meysse site. This spectrum will be used to initiate the seismic re-evaluation studies associated with the fourth periodic safety review of this site. ASN also asked EDF to continue with its investigations in order to obtain an improved characterisation of the existing faults round the Tricastin and Cruas-Meysse NPPs. Risks linked to extreme temperatures The inspections concerning the risks associated with extreme temperatures show that EDF’s organisation must be improved on the majority of sites. On several sites, ASN more particularly found a lack of forward planning in preparing the facility for the summer or winter configuration, which led to corrective action requests. In recent summers, at ASN’s request, EDF ran operating tests on the emergency diesel generator sets during a period of high temperatures. The purpose of these tests is to confirm the qualification demonstration of this equipment. During the heatwaves of the summer of 2022 (see “Notable events” in the introduction to this report), the maximum temperatures recorded on the sites did not reach the temperatures considered in the safety case. In the same way as during the previous heatwave episodes, ASN asked EDF to produce OEF. 2.4.7 Monitoring facilities compliance with the applicable requirements Maintaining the conformity of the facilities with their design, construction and operating requirements is a major issue insofar as this conformity is essential for ensuring compliance with the safety case. The processes employed by the licensee, notably during reactor outages, contribute to maintaining the conformity of the facilities. The identification and processing of deviations The checks initiated by EDF within the framework of its operating baseline requirements and the additional verifications requested by ASN, on the basis more particularly of OEF, can lead to the detection of deviations from the defined requirements, which must then be processed. These deviations can have a variety of origins: design problems, construction errors, insufficient expertise in maintenance work, deterioration through ageing, organisational shortcomings, etc. The steps taken to detect and correct deviations, specified in the Order of 7 February 2012, play an essential role in maintaining the level of safety of the facilities. “Real-time” checks Carrying out periodic test and preventive maintenance programmes on the equipment and systems contributes to identifying deviations. Routine visits in the field and technical inspection and verification of activities considered to be important for the protection of persons and the environment are also effective means of detecting deviations. Verifications during reactor outages EDF takes advantage of nuclear reactor outages to carry out maintenance work and inspections which cannot be performed when the reactor is generating electricity. These operations more particularly correct deviations already known, but can also lead to the detection of new ones. Before each reactor restart, ASN asks EDF to list any deviations not yet remedied, to take appropriate compensatory measures and to demonstrate the acceptability of these deviations with respect to the protection of persons and the environment for the coming production cycle. Ten-yearly verifications: conformity checks EDF carries out periodic safety reviews of the nuclear reactors every ten years, in accordance with the regulations (see point 2.9.2). EDF then carries out an in-depth review of the actual state of the facilities by comparison with the applicable safety requirements, more particularly on the basis of the in-service monitoring hitherto carried out, and lists any deviations. These verifications are supplemented by a programme of additional investigations, the aim of which is to check the parts of the facility which are not covered by a preventive maintenance programme. The additional verifications in response to ASN requests In addition to the steps taken by EDF with regard to its operating baseline requirements, additional checks are carried out at the request of ASN, whether, for example, with regard to OEF about events which have occurred on other facilities, after inspections, or after examination of the provisions proposed by the licensee within the context of the periodic safety reviews. Information of ASN and the public When a deviation is detected, and in the same way as any BNI licensee, EDF is required to assess the impacts on nuclear safety, radiation protection and protection of the environment. If necessary, EDF then sends ASN a significant event notification report. In addition, when the most noteworthy significant events occur, EDF informs the public by publishing notices on the website of the NPPs concerned, or in its external newsletter. INSPECTION CAMPAIGN ON THE CONTROL OF FIRE RISKS In 2022, ASN completed the campaign of in-depth inspections on the control of fire risks, which began in 2021. These inspections notably concerned the monitoring and control of sectorisation and the fire loads and fire-fighting resources. For some of the NPPs, these inspections were accompanied by a situational exercise involving the response teams. ASN made improvement requests for the management of equipment temporary storage sites and warehouses, which have significant calorific potential, as well as for detection and rapid handling of sectorisation anomalies. EDF must also improve the condition of the fire-fighting means, notably the fire hydrants and associated water networks. 300 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 10 • The EDF Nuclear Power Plants 10
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