EDF has also initiated a climatic monitoring programme to anticipate climate changes which could compromise the temperature hypotheses adopted in its baseline requirements. As for the other hazards, ASN asks EDF to learn the lessons from the various heatwave events, along with their effects on the installations. Other hazards The safety case for the EDF NPPs also takes account of other hazards such as high winds, snow, tornados, lightning, cold air temperatures, man-made hazards (transport of dangerous goods, industrial facilities, airplane crashes, etc.), and hazards affecting the heatsink. 2.4.6 Assessment of the risk prevention measures relating to hazards ASN checks that risks linked to hazards in the NPPs are taken into account, notably based on the reassessment of the design of the installations during the periodic safety reviews, analysis of the licensee’s baseline safety requirements, examination of significant events and the inspections performed on the sites. The steps taken to mitigate the risks linked to hazards are regularly inspected by ASN. The Fukushima Daiichi NPP accident led EDF to reinforce its organisation for the management of risks relating to extreme hazards. More specifically, networks of coordinators were set up for all the NPPs to oversee the implementation of the actions defined to deal with these hazards. Annual reviews are also held to improve this organisation. In general, ASN considers that major efforts are needed on most of the sites to improve how hazard risks are dealt with, in particular with regard to: ∙ the maintenance of the necessary equipment (sluice gates, fire doors, sensors, floor drains, etc.); ∙ risk assessments during maintenance operations and in the event an equipment malfunction is detected; ∙ the compliance with the corrective action deadlines identified by the annual reviews; ∙ the training of the coordinators and awareness-raising among the EDF and contractor personnel. Fire risks The fire risks are significant. ASN thus reminded EDF in 2016 that, for the purposes of the fourth periodic safety review of the 900 MWe reactors, it expected a well-structured and robust safety case based on a “Defence in Depth” approach. ASN examined the justification methods produced by EDF, along with the corresponding modifications, and obtained the opinion of the Advisory Committee for Nuclear Reactors (GPR) in 2019. This examination shows that the changes proposed by EDF represented considerable improvements to the fire risk safety case (for example, sectorisation resistance studies, account taken of the effect of smoke). In addition, the new methods adopted identified sectorisation aspects for which correct working is particularly important. For example, the fire doors which are required to be closed were identified and will be subject to specific monitoring. These methods will also be implemented during the fourth periodic safety review of the 1,300 MWe reactors On the sites, ASN sees no significant change with regard to control of fire risks, with a level that remains lower than that expected. The number of outbreaks of fire and significant firerelated events is slightly down in 2022 by comparison with 2021. Two outbreaks of fire occurred in 2022 outside the limited access areas and led to activation of the PUI on the site concerned. ASN has observed certain improvements in the management of this risk in the NPPs. However, the tightened inspections campaign (see box next page) shows that improvements are needed for better control of this risk. Fire detection management and personnel training are in general satisfactory and, since the end of 2021, ASN notes that the alarm verification officers in all the NPPs have been working in pairs. EDF also continued with its measures to improve management of the fire risks in the premises identified as being particularly sensitive to this hazard in the light of the potential consequences for safety. However, progress is required in application of the rules in the field. ASN thus considers that the efforts made by the NPPs to take corrective measures must continue and the personnel must receive greater support in this respect and be given the time needed to perform the required actions. Finally, further to an ASN request made in 2019, EDF presented ASN in 2022 with the strategy to be deployed as of 2024 regarding the organisation of fire-fighting. Changes are planned with regard to protection equipment, personnel training, but also the links with the département level fire and emergency services. Explosion risks ASN checks the explosion risk prevention and monitoring measures, paying particular attention to ensuring that it is taken into account in EDF’s baseline safety requirements and organisation. ASN also ensures compliance with the “EXplosive ATmospheres” (ATEX) regulations to ensure worker protection. The management of explosion risks is not yet satisfactory for all the sites. Certain maintenance and inspection work required by EDF’s internal doctrine is not always carried out satisfactorily, notably with regard to the risks related to the presence of hydrogen in the installations. Furthermore, ASN observes that the integration of OEF and the processing of certain deviations are sometimes postponed and this is not always justified given the potential safety consequences. During inspections, ASN is particularly vigilant with regard to the inspections and corrective measures taken by EDF to guarantee the compatibility of the electrical equipment with use in rooms where an explosive atmosphere is liable to form. The management of the gas storage yards is also the subject of particularly close attention during the inspections. ASN notes the efforts made by EDF to reduce these deviations, notably through the implementation of reinforced monitoring and the deployment of action plans leading to equipment replacement. ASN considers that EDF must continue to pay particular attention to this subject and ensure that the explosion risk prevention approach is implemented with all necessary rigour on all the sites. Internal flooding risks In 2019, ASN asked EDF to supplement its approach in order to better control the internal flooding risk, ensure correct operation of the floor drains, reinforce its maintenance of the lines liable to lead to internal flooding and ensure improved management of their ageing. In response to these requests, EDF implemented improvement measures. In addition, EDF is continuing its field visits to identify the piping which could cause internal flooding in the electrical buildings, which are particularly vulnerable to this risk, in order to assess the need to reinforce its maintenance. In accordance with ASN’s requests, EDF will extend these surveys to the other buildings. ASN sees as positive the fact that EDF has initiated the refurbishment of the circuits of certain cooling systems that are particularly susceptible to corrosion. Finally, for the fourth periodic safety review of the 900 MWe and 1,300 MWe reactors, EDF has updated its safety case regarding ASN Report on the state of nuclear safety and radiation protection in France in 2022 299 • 10 • The EDF Nuclear Power Plants 10 01 07 08 13 AP 04 06 12 14 03 09 05 11 02
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