ASN Report 2022

As in the preceding years, ASN notes that the significant events management process is well mastered on the whole and effectively mobilises the site players up to senior management level. With regard to fire risk prevention, ASN observes that the site has improved in several areas, such as the management of fire loads and sectorisation. Moreover, weekly patrol rounds have been put in place and are proving effective. Nevertheless, occasional findings reveal that these improvements must be consolidated and further efforts must be made in this area. The site’s emergency response organisation was deployed during a national exercise, as well as in two real situations (discharges causing iridescent sheens on the Moselle River and detection of a discharge of ammonia in the atmosphere). The organisation and resource deployment associated with these events ran smoothly. Nevertheless, the licensee’s lack of knowledge of the monochloramine production facility created difficulties in the management of the event involving the ammonia discharge detection. With regard to environmental protection, the site remains marked by weaknesses, as some events reveal room for improvement in the control of specific facilities and activities relating to discharges and monitoring of the environment. Controlling the risk of proliferation of microorganisms in the cooling towers still necessitates reinforced biocide treatments which have consequences on the aqueous discharges. Lastly, the site saw an improvement in several radiation protection themes in 2022: management of sources, access to red (prohibited) controlled areas, control of industrial radiography work, number of significant events. The radiation protection skills centres have been put in place and correctly equipped, even if work on facilitation and uptake of the initiative still has to be developed. Deficiencies nevertheless persist, particularly in the control of accesses to and marking out of the limited stay (orange) areas and the dispersion of contamination. Lastly, with regard to occupational safety, the conformity of the electrical installations needs to be improved. 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 from 1967 to 1991, for which the final 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 With regard to nuclear safety, given that the reactors did not function in 2022 due to the repair work on the pipes with stress corrosion cracks, ASN considers that the performance of the Chooz B NPP cannot be compared with that of the other NPPs. ASN considers moreover that the radiation protection and environmental performance of the Chooz B NPP is in line with ASN’s general assessment of the EDF plants. As far as nuclear safety is concerned, even if the reduced level of activity resulting from the reactor outages does not enable a trend to be established with respect to the 2021 assessment, ASN considers that standard of safety has remained satisfactory. It nevertheless notes that the operational documentation and the organisation of the department responsible for operational management of the reactors can be further improved to limit sources of error. Particular attention must also be focused on the equipment lockout/tagout process, which has been the cause of several significant events. With regard to maintenance, ASN underlines the satisfactory management of the exceptional volume of activity created by the build-up of inspections performed on account of the maintenance outages on the two reactors and the activities induced by the stress corrosion problem. In the field of radiation protection, the annual result concerning compliance with the collective dosimetry targets is satisfactory. Shortcomings in the control of radiological cleanliness on certain work sites, however, caused numerous contaminations, particularly of garments, at the beginning of the scheduled maintenance operations on reactor 2. ASN noted that the licensee took corrective action immediately, and urges it to remain particularly vigilant on this subject. The licensee must also encourage rigour in workers’ individual behaviours and be attentive to the management of industrial radiography work, which showed some weaknesses. ASN considers that the site’s environmental protection organisation is on the whole satisfactory, as it was in the preceding year. The labour inspections revealed no major findings. The subjects addressed are taken seriously by the employer, with the intention to make them progress. Reactor A undergoing decommissioning In 2022, the works to treat the waste resulting from the decommissioning of equipment inside the pressure vessel were started. The emptying of the reactor building pool in order to decommission the reactor vessel could not be undertaken due to the delay in installing an evaporator intended to treat the pool water prior to discharge. Commissioning of this evaporator is planned for early 2023. The decommissioning work on all the equipment still present in the bunkers of the “auxiliary” vault continued. This work is carried out mainly by remote operation using a robotic arm. The decommissioning work on the effluent treatment station equipment items that are not necessary for treating the water from the rock or floor drains also continued. With regard to radiation protection, the prevention of worker contamination with alpha particles is the main challenge during the facility dismantling phases. ASN considers that the licensee has made progress in this area, with the setting up of a medical monitoring system tailored to ensure faster detection of cases of contamination, which remained at a low level. 58 ABSTRACTS – ASN Report on the state of nuclear safety and radiation protection in France in 2022 Regional overview of nuclear safety and radiation protection • GRAND EST •