ASN Report 2020

ASN has noted the strong commitment of the reactor operating teams to rigorous application of the operating rules, borne out by the absence in 2020 of reactor trips or events during several reactor shutdowns. The efforts in maintenance have resulted in improved monitoring of the technical actions andmeasures that limit the deviations during maintenance operations and on worksites. This improvement, however, is offset by longer system return- to-service times, which has an impact on the end-of-outage time frames. Alongside this, the impact of the health crisis was well managed and planned for. The number of significant events followed the improvement trend observed from the qualitative aspect, with 40 events reported compared with 51 in 2019. Nevertheless, many of these events still have to be put down to organisational or human def iciencies, in line with the preceding years; inspections carried out in 2020 highlighted numerous shortcomings in the conformity checks carried out as part of the ten-yearly outages of reactors 1 and 2 in 2016 and 2018, obliging the site to repeat a large number of conformity checks retrospectively. In addition, several recurrent outages of the Plant Radiation Monitoring System (KRT) and the Component Cooling System (RRI) are to be noted. Lastly, some minor deviations were identified in the embodiment or taking into consideration of the modifications to be made to the fire-fighting systems. The site’s reporting and analysis of signif icant events remains satisfactory, with deadlines being observed and analyses of good quality. The initial results of the operating rigour improvement plan put in place by EDF further to the negative trend diagnosed in 2019 are encouraging on the whole; its must be pursued in order to conf irm and build on these results, particularly for the organisation, performance and monitoring of future maintenance actions. With regard to the environment, 2020 was less constrained than 2019, which was marked by the lasting low-water period of the Moselle river. Nevertheless, the site’s exposure to climatic risks, bringing increased needs for cleaning of the intermediate cooling system heat exchangers among other things, remains an issue requiring particular attention. Furthermore, a case of exceeding of the first Legionella concentration threshold was observed in the tertiary cooling system in 2020. This is an issue specific to the site that requires special management of the biocide treatment campaigns throughout the year. A few events involving accidental spillages of chemical products (hydrazine, ferrolin) underline the need for the site to improve its product management and containment practices. With regard to radiation protection, signif icant efforts have been made in worksite preparation f rom the radiological risks and contamination control aspects; it could benef it from being based on more direct consideration of the actual state of the facilities and its development, rather than on theoretical aspects of the optimisation approach. In addition, several deviations concerning fundamental aspects such as the control of access to prohibited areas have been noted and necessitate specific actions by the licensee. Lastly, with regard to occupational safety, the Cattenom NPP has demonstrated its ability to put in place the necessary measures in the context of the health crisis and to adapt the site’s organisation accordingly. The hydrazine spillage incident mentioned above brought to light a situation of concern within a service provider company, which received particular attention from the labour inspector. Chooz nuclear power plant The Chooz NPP operated by EDF is situated in the municipality of Chooz, 60 km north of Charleville‑Mézières, in the Ardennes département . The site accommodates the Ardennes NPP, called Chooz A, comprising reactor A (BNI 163), operated f rom 1967 to 1991, for which the f inal shutdown and decommissioning operations were authorised by Decree 2007‑1395 of 27 September 2007, and the Chooz B NPP, comprising two 1,450 MWe reactors (BNI 139 and 144), commissioned in 2001. Reactors B1 and B2 in operation ASN considers that the nuclear safety performance of the Chooz B NPP is on the whole in line with the general assessment of EDF, but the radiation protection performance is below the average for the EDF plants. The environmental protection performance stands out positively and is considered satisfactory. With regard to nuclear safety, ASN observes that the sustained progress in reactor operation witnessed over the last few years is continuing, notably with a reduction in the number of significant events despite a context of intense activity linked to the ten-yearly outage of reactor 1. Particular vigilance must be maintained regarding the management of operational documents and the traceability of validation of the inspections and the monitoring of the state of the installations. With regard to maintenance, efforts to improve work intervention rigour must be continued. Particular attention must also be paid to the organisation of activities to guarantee the long-term durability of equipment qualif ication for accident conditions and the quality of the risk analyses. In the area of radiation protection, lack of rigour in individual behaviour and shortcomings in radiological cleanliness are still observed too frequently during the ten-yearly outage of reactor 1. The licensee’s in-depth reflection on the optimisation of radiation protection on worksites with high radiological risks has not yet fully borne fruit. An improvement is nevertheless noted in meeting the collective dosimetry targets during this ten-yearly outage. ASN considers that the site’s environmental protection organisation is on the whole satisfactory. Improvements are nevertheless expected in the prioritisation of curative maintenance work on the equipment involved in controlling the microbiological risks. With regard to labour inspection, the health crisis occupied an important position in ASN’s inspections and in the discussions 60 ASN Report on the state of nuclear safety and radiation protection in France in 2020 REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION