Les cahiers de l'ASN #03 - 10 years after Fukushima

Adapting the French stress tests (ECS) specifications to all the facilities, in the light of situations leading to large-scale releases, and prioritising the facilities according to their potential safety implications represented a very real challenge that was specifically French! In brief Unlike the NPPs, which represent a homogeneous fleet of installations managed by a single licensee, the other nuclear facilities vary and are managed by different licensees, such as CEA, Framatome, the Institut Laue‑Langevin, ITER Organization* and Orano. Research facilities S ome nuclear facilities are devoted to scientific and technological research. In France, these facilities are mainly operated by CEA *. It also operates facilities that support its research work (materials and waste storage, effluent treatment facilities, etc.). For CEA, the stress tests confirmed a certain number of weak points in the older facilities, such as the Masurca and Osiris reactors or the MCMF storage facility, which were in service in 2011. The stress tests led to their final shutdown and the removal of several tons of fissile materials to more robust storage facilities, in order to significantly reduce the risks. Between 2013 and 2014, several tons of fissile materials were removed from the Masurca research reactor, representing some 38,000 objects! The stress tests allowed the storage facilities to be reorganised in order to improve safety and the permanent facilities completed the necessary work (more specifically, improvements to maintaining ventilation, earthquake resistance and the installation of an earthquake detection sensor). The crisis management rooms still need to be built and legacy waste retrieved and conditioned. For its part, the Institut Laue- Langevin* met an ambitious schedule , between 2013 and 2018, and completed an exemplary range of post-Fukushima reinforcement measures on the high-flux research reactor (RHF*). The wide-ranging works were completed in 2018, notably with the construction of new, robust crisis management rooms, reinforced leak tightness of the reactor building to cope with extreme flooding and the commissioning of back-up systems to resupply the reactor and spent fuels with water in the event of an accident. Installations with lesser safety implications For these facilities, ASN specified a calendar for the submission of the stress tests, which ran until 2020. The study of the consequences of a major accident on a site with several facilities with lesser safety implications was taken into account in the reinforced crisis management provisions. However, these stress tests showed that there was no need to adopt “hardened safety core” type measures. Storage facilities for legacy waste and reactors undergoing decommissioning The stress tests confirmed that a certain number of legacy waste storage facilities were insufficiently safe and that the retrieval and conditioning operations needed to be speeded up . The licensees (CEA, EDF and Orano) are encountering a certain number of technical difficulties in carrying out these operations. ASN considers that the management of these projects needs to be made more robust. 10 years after Fukushima, what safety improvements for nuclear facilities in France? • 15