Abstracts ASN Report 2021

TRICASTIN SITE The Tricastin nuclear site, situated in the Drôme and Vaucluse départements, is a vast industrial site accommodating the largest concentration of nuclear and chemical facilities in France. It is situated on the right bank of the Donzère‑Mondragon Canal (a diversion channel of the river Rhône) between Valence and Avignon. It occupies a surface area of 800 hectares covering three municipalities, namely Saint‑Paul-Trois‑Châteaux and Pierrelatte in the Drôme département, and Bollène in the Vaucluse département. The site harbours a large number of installations, with a NPP comprising four 900 MWe reactors, nuclear fuel cycle facilities, and lastly the Tricastin Operational Hot Unit (BCOT), which fulfilled maintenance and storage functions. Tricastin nuclear power plant The Tricastin NPP comprises four 900 MWe PWRs: reactors 1 and 2 were commissioned in 1980 and constitute BNI 87, while reactors 3 and 4, commissioned in 1981, constitute BNI 88. ASN considers that the overal l performance of the Tricastin NPP with regard to nuclear safety, radiation protection and environmental protection in 2021 is in line with ASN’s general assessment of EDF plant performance. ASN considers that the nuclear safety performance of the NPP, which has been improving since 2019, is in line with the general assessment of the EDF plants. From the maintenance aspect, the four reactors of the Tricastin NPP were shut down in 2021 for scheduled maintenance and partial refuelling, reactor 2 having undergone its fourth ten-yearly outage, which represents tightened maintenance. ASN considers that these outages are managed with rigour, particularly in the planning and preparation of the maintenance activities. The modif ications planned to reinforce safety during the fourth ten-yearly outage of reactor 2 were integrated satisfactorily. Control of the integrity of the first barrier, that is to say the fuel assembly claddings, is also improving. The attentiveness of the independent safety organisation, assessed in 2021, is deemed satisfactory and the quality of the significant events analysis remains good. Weaknesses are nevertheless still observed in some areas, such as the monitoring of control room activities and system configuring. With regard to radiation protection, ASN considers that the NPP’s performance is in line with the general assessment of the EDF plants and has improved with respect to 2020, continuing the momentum that began in 2019. The dosimetry received by the personnel of EDF and outside contractors alike seems under control, and significant progress has been made in establishing the forecast dosimetric evaluations of the outages. As stated in 2020 however, the radiological cleanliness of the premises during reactor outages could be improved. ASN considers that the environmental protection performance of the NPP is down compared with 2020 and slightly below its general assessment of the EDF plants in this area. The liquid pollution containment exercise organised by ASN showed that the preparation and the speed of the responses planned for these situations needed to be reinforced. The pollution of groundwater at the end of the year by effluents containing tritium and the reactive inspection by ASN demonstrated the need to improve the management of effluent transfers and interim storage. ASN expects to see improvements in this area in 2022. With regard to labour inspection, ASN considers the site’s results show a distinct improvement. Accident prevention, particularly during reactor outages, has been well managed, with a drop in the number of accidents not necessitating lost-time. ASN nevertheless notes that one serious accident occurred this year during the intervention of a diver. THE “NUCLEAR FUEL CYCLE” FACILITIES The Tricastin fuel cycle installations mainly cover the upstream activities of the “fuel cycle” and, as of the end of 2018, they are operated by a single licensee, Orano Cycle, which became Orano Chimie-Enrichissement on 1 January 2021 and is called Orano hereinafter. The site comprises: • the TU5 facility (BNI 155) for converting uranyl nitrate UO2(NO3)2 resulting from the reprocessing of spent fuels into triuranium octoxide (U3O8); • the W plant (ICPE within the perimeter of BNI 155) for converting depleted UF6 into U3O8; • the former Comurhex facility (BNI 105) and the Philippe Coste plant (ICPE within the perimeter of BNI 105) for converting uranium tetrafluoride (UF4) into uranium hexafluoride (UF6); • the former Georges Besse I plant (BNI 93) for the enrichment of UF6 by gaseous diffusion; • the Georges Besse II plant (BNI 168) for centrifuge enrichment of UF6; • the uranium storage areas at Tricastin (BNIs 178 and 179) for storing uranium in the form of oxides or UF6; • the maintenance, liquid effluent treatment and waste packaging facilities (IARU –BNI 138); • the Atlas process samples analysis and environmental monitoring laboratory (BNI 176); • a Defence Basic Nuclear Installation (DBNI), which more specif ically accommodates former facilities undergoing decommissioning, radioactive substance storage yards and a liquid effluent treatment unit. Following the inspections it conducted in 2021, ASN considers that the level of safety of the Orano facilities on the Tricastin site is improving. The year 2021 was marked by the change of licensee planned for through the PEARL project, with Orano Cycle –the single licensee of the platform– becoming Orano Chimie‑Enrichissement on 1 January 2021. The Philippe Coste plant has reached more stable operating conditions. ASN has updated its requirements and monitored continuation 44 ABSTRACTS – ASN Report on the state of nuclear safety and radiation protection in France in 2021 REGIONAL OVERVIEWOF NUCLEAR SAFETY AND RADIATION PROTECTION