ASN Report 2020

346 ASN Report on the state of nuclear safety and radiation protection in France in 2020 13 – DECOMMISSIONING OF BASIC NUCLEAR INSTALLATIONS 6 3 1 5 2 2 4 New waste retrieval management at Saclay Commissioned in 1971, Basic Nuclear Installation (BNI) 72 comprises the facilities for storing and treating the solid radioactive waste produced essentially by the reactors, laboratories and units situated in the Saclay centre. Further to a meeting of the Advisory Committee of Experts in 2009, the Alternative Energies and Atomic Energy Commission (CEA) engaged a process to retrieve and remove the waste in order to reduce the source term of the facility. This complex process is currently continuing with the facility’s Waste Retrieval and Packaging (WRP) project, which will last several decades. As BNI 72 is one of the CEA facilities containing the most significant potential source term in the event of an accident, the removal of this source term has been classified among the top priorities of the CEA decommissioning strategy. The notable operation in this WRP phase is the future “EPOC” process, a French acronym standing for “Removal of the spent fuel drums”, for which the project and the safety case were presented as part of the BNI 72 decommissioning file submitted in 2015. The aim of this process is to retrieve, characterise, sort and package drums containing a mix of wastes and pieces of fuel, currently stored in 15 wells in building 114 1 . In view of their deteriorated condition and their contents, the 144 drums in question cannot be treated by the facility with its current means. EPOC is a complex process line consisting of a retrieval hood 2 positioned above the well, allowing the drums to be extracted and transferred to a shielded cell using a transfer trolley. The “retrieval hood” is equipped with a video camera which serves to determine the state of the drum and then the retrieval strategy, using different tools as appropriate for the condition of the drum. The shielded line enables the drums to be treated and the fuel and waste they contain to be repackaged. The retrieval hood positions itself vertically on the docking platform 3 , the drum is lowered into the “ chapel” (underground cavern), then transferred to the sorting cell where the fuel is placed in a can. This can is transferred to the adjacent fuel cell and the other waste is lowered back down into the cavern for treatment and packaging 4 . The repackaged fuels are then introduced into a transport package for subsequent storage in a dedicated facility. The maintenance and testing station 5 , which is three storeys high, is used for the maintenance and decontamination of the retrieval equipment and for the equipment crane tests and operator training. The method of drum retrieval will differ according to their condition 6 . If a drum is intact, the retrieval hood picks it up as a single block and transfers it to the shielded cell. If the drum is damaged, the retrieval hood is equipped with a specific tool which cuts away the drum lid so that the contents can be retrieved. Lastly, if the drums are very severely damaged, the CEA has planned for specific equipment that enables the various containers to be cut up within the well, and a gripper to retrieve the container and its contents. The fragments are placed in small containers. Once filled, these containers are transferred to the shielded line for sorting and packaging. In this case, there is a large number of transfer operations which means that the retrieval time is increased. Removal from storage using EPOC will start around 2029 and is forecast to last 15 years.