ASN Report 2018

GRAND EST REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION radiation protection but a persistent shortfall inmaintenance and operating operations. The year 2018 was thus marked by several events associated with maintenance non-qualities, leading to unscheduled shutdowns or replacements of parts. Some of these events are linked to modifications made in 2016 during the third 10-yearly outage of reactor 1, highlighting some one-off shortcomings in their integration; others confirm the need to reinforce the verification of the technical actions of the operators or the monitoring of service providers. Nevertheless, the site’s ability to manage incidental events, once clearly identified, remains satisfactory. An action plan to improve the way operating activities are carried out was put in place in late 2017. ASN notes a reduction in the number of events caused by a lack of vigilance, but considers that the action plan has not yet brought adequate results in the preparation and deployment phases, where control and rigour can be improved. ASN considers that the efforts undertaken to achieve conformity in environmental aspects must be extended to a reinforcement of the environmental protection culture, to better prevent accidental spillages, inspection equipment downtimes and the crossing of pre-alarm thresholds. The finely-tuned coordination of the biocide treatments of the cooling towers in 2018 enabled the chemical andmicro- organism discharge values to be kept within permissible limits, but the need to perform treatments, including during cold periods – which is a local particularity – could necessitate the adaptation of the prescriptive framework governing discharges. Lastly, the positive dynamics in radiation protection management observed in 2017 were confirmed in 2018 in a context of more sustained activity: the efforts made with regard to radiological cleanliness and dosimetric optimisation must be continued. 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 comprises 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 two reactors each with a power rating of 1,450 MWe (BNIs 139 and 144) commissioned in 2000. Reactors B1 and B2 in operation ASN considers that the performance of the Chooz B NPP with regard to nuclear safety, radiation protection and environmental protection is, on the whole, in line with the general assessment of EDF plant performance. With regard to nuclear safety, ASN observes improvements in reactor operation but considers that the required level of rigour has not yet been reached; the licensee must not reduce its efforts in this area. The significant events, which remain numerous, also underline shortcomings in activity preparation and operator training. The quality of the operational documentation and its updating is moreover considered a weak point for the operational control and maintenance activities alike. In this latter respect, care must be taken to ensure that equipment modifications or changes in maintenance requirements are duly integrated. With regard to radiation protection, ASN considers the site’s performance satisfactory on the whole. Dosimetry and radiological cleanliness were well managed during the reactor outages. The site must nevertheless maintain its vigilance to ensure compliance with the basic radiation protection actions. Lastly, ASN considers that the sites organisation for environmental protection is satisfactory on the whole. Certain events nevertheless revealed uncontrolled discharges of cooling fluids and occasional failures in equipment involved in the monitoring of liquid and gaseous discharges. Reactor A undergoing decommissioning The decommissioning work on the reactor A pressure vessel continued in 2018, including in particular the commissioning of the packaging facility for waste resulting from the underwater cutting up of the reactor pressure vessel and the cutting up of its closure head. The decommissioning work on the equipment still present in the nuclear auxiliaries cavern bunkers was interrupted during the year. This work, chiefly carried out by remote operation, nevertheless involves manual interventions which were poorly evaluated in the initial work file and necessitated reviewing of the radiation protection measures. With regard to the environment and nuclear safety, ASN considers that the decommissioning operations have been carried out satisfactorily. No event occurred in the area of radiation protection in 2018. The licensee must nevertheless remain vigilant with regard to the risk of contamination by alpha particles in the monitoring of its service providers. 50  ASN report on the state of nuclear safety and radiation protection in France in 2018