ASN Report 2020

action plans, but considers that if they are to be effective, the personnel must be given greater support with implementing them. ASN thus observed that in 2020, EDF had continued its actions to reduce errors in fire risk management in the premises identified as being particularly susceptible to this hazard. In addition, the time taken to remedy certain deviations or to take corrective actions as a result of experience feedback needs to be reduced. Finally, following an ASN request in 2019, EDF initiated a review to improve its firefighting organisation, notably by reinforcing the capacity of its response resources to deal with an established fire. Explosion risks Despite the steps taken by EDF, management of the explosion risks is not yet satisfactory on all the nuclear reactors. Certain maintenance work and inspections required by EDF’s internal doctrine are not always carried out satisfactorily. Furthermore, ASN observes that the updating of certain documents (notably the procedures for periodic tests or for checks on piping carrying hazardous fluids), the integration of operating experience feedback, the processing of certain deviations and the deployment of certain modifications are sometimes postponed and this is not always justified given the potential safety consequences. ASN notes the efforts made by EDF to reduce these deviations through the implementation of reinforced monitoring and deployment of action plans. Furthermore, in 2020, EDF worked on updating documents concerning protection against explosions, required by the regulations concerning the risks involved in the formation of ATEX and conducts conformity audits on equipment that is supposed to comply with the requirements of these regulations. This process should be continued in the coming years. ASN thus considers that EDF must continue to pay particular attention to this point and ensure that the explosion risk prevention approach is implemented with all necessary rigour on all the sites. Internal flooding risks Considerable efforts are required on most sites to improve control of the flooding risk, in particular with respect to: ∙ the maintenance of the necessary equipment (piping, floor drains, etc.); ∙ the risk assessments during maintenance operations and in the event of detection of a malfunction of a necessary equipment item; ∙ 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. In 2019, ASN thus sent requests to EDF asking it to supplement the approach adopted for improved control of the internal flooding risk, to ensure the correct operation of the floor drains, to reinforce maintenance of the piping liable to lead to internal flooding and to ensure improved management of their ageing. EDF has initiated 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 their 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 reactors, EDF has updated its safety case regarding internal flooding risks, notably by considering several possible water flow routes. 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. For example, in 2020, EDF reported a significant event, rated level 2 on the International Nuclear and Radiological Event Scale (INES scale) by ASN (see box page 302), owing to the lack of seismic resistance of equipment necessary for the correct functioning of the emergency diesel generator sets on several NPPs. An earthquake occurred on 11 November 2019 in the municipality of Le Teil (Ardèche département ). Following this earthquake, EDF implemented 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 Cruas-Meysse NPP sites. EDF’s answer transmitted in 2020 is currently being examined. 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. The defined requirements The Order of 7 February 2012 states that a defined requirement is a “ requirement assigned to a Protection Important Component (PIC) of persons and the environment, so that it can, with the expected characteristics, perform the function stipulated in the safety case mentioned in the second paragraph of Article L. 593-7 of the Environment Code, or to an Activity Important for the Protection (AIP) of persons and the environment, so that it can meet its objectives with regard to this safety case ”. For the PIC, these requirements can in particular concern: ཛྷ the characteristics of the materials used; ཛྷ the manufacturing, assembly, erection and repair processes; ཛྷ the physical parameters and criteria characteristic of the performance of the PIC. For the AIP, these requirements can in particular concern: ཛྷ the skills needed to perform the activity; ཛྷ any qualifications necessary; ཛྷ checks and hold points; ཛྷ the equipment and hardware needed to enable the activity to be carried out in accordance with the regulatory or even contractual requirements, such as to guarantee compliance with the safety case. 300 ASN Report on the state of nuclear safety and radiation protection in France in 2020 10 – THE EDF NUCLEAR POWER PLANTS