ASN Report 2018

EDF regularly reports 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. EDF must therefore continue with these inspections to ensure the compliance of its facilities with the provisions for dealing with an earthquake. In 2018, EDF more particularly reported a significant safety event concerning a lack of seismic resistance on the part of catwalks (see box). • Hazards linked to extreme temperatures The inspections concerning the hazards associated with extreme temperatures show that EDF’s organisation needs to 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. During its inspections ASN repeatedly notes that EDF does not systematically initiate the required measures if certain temperature thresholds are exceeded. These findings led ASN to issue requests for corrective action. The risk assessments associated with the deployment of countermeasures should also be improved. • Lightning risks The inspections relating to lightning reveal the need on all sites to set up an organisation and reinforced oversight to improve the integration of the regulatory requirements concerning the management of this hazard. The lightning risk assessments can be based on information which does not actually reflect the real situation on the facilities. ASN also observes a significant delay in the performance of the work identified in the technical studies. The deadlines for performance of the periodic checks on the lightning protection systems by the competent inspection organisations are on the whole not adhered to. These points were the subject of requests for corrective action. EDF has defined a programme of work to improve the situation. 2.4.7  –  Monitoring facilities compliance with the requirements Maintaining the compliance of the facilities with their design, construction and operating requirements is a major issue insofar as this compliance is essential in demonstrating the protection of interests. The processes employed by the licensee, notably during reactor outages, contribute to maintaining the compliance of the facilities with the requirements resulting from this demonstration. • Reactor outages Nuclear power reactors need to be periodically shut down in order to renew the fuel, which gradually becomes depleted during the electricity production cycle. One third or one quarter of the fuel is thus renewed at each outage. These outages allow temporary access to certain parts of the facility which are not accessible during production, although with specific radiation protection precautions. They are therefore an opportunity to verify the condition of the equipment by running checks and tests and performing maintenance work, as well as to carry out work on the facility. These refuelling outages can be of several types: ∙ ∙ Refuelling Outage (ASR) and Partial Inspection (VP) outage: these outages last a few weeks and are devoted to renewing part of the fuel and conducting a programme of verification and maintenance that is more extensive during a Partial Inspection (VP) than during a Refuelling Outage (ASR). ∙ ∙ Ten-yearly Outage (VD): this outage entails a wide-ranging verification and maintenance programme. This type of outage, which lasts several months and takes place every 10 years, enables the licensee to carry out major operations such as a complete inspection and hydrotesting on the primary system, a containment test or incorporation of design changes as a result of the periodic safety reviews. These outages are scheduled and prepared for by the licensee several months in advance. ASN checks the steps taken by the licensee to ensure the safety of the facility, protection of the environment and radiation protection of the workers during the outage, as well as the safety of the reactor for the next production cycle. Significant safety event concerning lack of seismic resistance In 2018, EDF reported a significant safety event concerning a lack of seismic resistance with regard to metal catwalks in Belleville-sur-Loire NPP reactor 2, Cattenom NPP reactors 2, 3 and 4, Flamanville NPP reactors 1 and 2, Golfech NPP reactor 1, Paluel NPP reactors 1, 2, 3 and 4, Penly NPP reactors 1 and 2 and Saint-Alban/Saint-Maurice NPP reactors 1 and 2. EDF stated that these catwalks could constitute a hazard to equipment important for the protection of interests located nearby or underneath, in the event of an earthquake. An earthquake could then lead to situations not covered by the nuclear safety case. EDF has started work to reinforce these catwalks and defined a schedule for all the reactors concerned. ASN considers this to be acceptable in the light of the nuclear safety implications. For the reactors with catwalks still to be reinforced, ASN oversaw performance of this work and stipulated compliance with this schedule. In the light of its potential consequences for nuclear safety in the event of an earthquake, ASN rated this significant event level 1 on the INES scale for the 15 reactors concerned. ASN report on the state of nuclear safety and radiation protection in France in 2018  291 10 – EDF NUCLEAR POWER PLANTS 10