Auvergne‑Rhône‑Alpes 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 nuclear power plant comprising four 900 MWe reactors, “nuclear fuel cycle” facilities, and a facility which fulfilled maintenance and storage functions and is now undergoing decommissioning. Tricastin nuclear power plant The Tricastin NPP comprises four 900 MWe PWRs: reactors 1 and 2, commissioned in 1980, constitute BNI 87, while reactors 3 and 4, commissioned in 1981, constitute BNI 88. ASNR considers that the nuclear safety performance of the Tricastin NPP is in line with ASNR’s general assessment of EDF plant performance. Its environmental performance stands out favourably. Lastly, ASNR considers that performance in the field of radiation protection has improved thanks to the implementation of an action plan in this area, and is now in line with ASNR’s general assessment of the performance of EDF’s NPPs in this area. In terms of nuclear safety, ASNR considers that the nuclear power plant’s performance remains fairly satisfactory, although no progress has been made since 2024. In terms of reactor operation and management, ASNR considers that particular attention must be paid to ensure high standards for the preparation of activities and associated documents, particularly when part of routine operating activities (periodic tests, configuration of circuits, etc.). A dedicated action plan has been deployed by EDF since 2025 and ASNR considers that it should be continued in 2026. As far as the maintenance of the facilities is concerned, the performance of the Tricastin NPP is considered satisfactory. ASNR considers that EDF satisfactorily carried out the planned activities for the four reactor outages of 2025 and complied with the corresponding safety requirements. In the field of radiation protection, the site’s performance, which was lagging behind in 2024, has improved in 2025. In particular, the site has put in place a plan to improve radiation protection, which is showing initial results. Nevertheless, the situation remains delicate and EDF must maintain its efforts in 2026, with a focus on strengthening the radiation protection culture of its employees and outside contractors. In terms of environmental protection, ASNR believes that the plant’s performance stands out favourably compared to the general assessment of EDF’s NPPs. The organisation of the site to meet the regulatory requirements in the area of environmental protection has improved. Progress has been made, particularly in the areas of effluent containment and retention systems, to prevent events affecting the surrounding environment. In terms of occupational health and safety, ASNR considers that the site’s results are lagging behind. Although there were no severe accidents in 2025, the accident rate was higher than in 2024. In particular, ASNR has identified a need for a strong focus on preventing risks associated with tripping, movements and postures. “NUCLEAR FUEL CYCLE” FACILITIES The Tricastin “fuel cycle” facilities mainly cover the upstream activities of the “fuel cycle” and are operated by Orano ChimieEnrichissement, 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 uranium hexafluoride (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 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 (BNI 178-U) for storing uranium in the form of oxides or UF6; • the maintenance, liquid effluent treatment and waste conditioning facilities (IARU – BNI 138); • the Atlas process samples analysis and environmental monitoring laboratory (BNI 176); • a Defence Basic Nuclear Installation (DBNI), which more specifically accommodates former facilities undergoing decommissioning, radioactive substance storage areas and a liquid effluent treatment unit. Following the inspections it conducted in 2025, ASNR considers that the level of safety of the Orano facilities on the Tricastin site is satisfactory. In 2025, ASNR noted that external hazards, in particular flooding, had been well accounted for as these had been monitored during seven inspections at the site. In 2025, ASNR conducted a campaign of simultaneous unannounced inspections of the 178-U, 138, 155 and 168 BNI nuclear facilities and the entire platform, focusing on emergency organisation. One of the objectives was to test Orano’s organisation through exercises. In this context, the inspectors carried out a number of situational exercises and checked the training of crisis team members, as well as the periodic inspections and tests carried out on emergency equipment. These inspections showed that the licensee’s organisation appears to be appropriate. To ensure progress in dealing with the reprocessing of diverse radioactive substances stored on the site, ASNR has asked Orano to present an annual progress report on its action plan for the reprocessing of these substances. In April 2025, ASNR gave Orano formal notice to complete the removal of unburnt fluoride from Area 61, located on the perimeter of BNI 105, by 30 September 2026. In 2026, ASNR will continue to closely monitor the implementation of the action plan provided by Orano for these various liabilities. ABSTRACTS – ASNR Report on the state of nuclear safety and radiation protection in France in 2025 41
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