The fuel assemblies are then sheared and dissolved in nitric acid to separate the pieces of metal cladding from the spent nuclear fuel. The pieces of cladding, which are insoluble in nitric acid, are transferred to a compacting and conditioning unit. The nitric acid solution comprising the dissolved radioactive substances is then processed in order to extract the uranium and plutonium and leave the fission products and other transuranic elements. After purification, the uranium is concentrated and stored as uranyl nitrate UO2(NO3)2. It will then be converted into a solid compound (U3O8) called “reprocessed uranium” in the TU5 facility on the Tricastin site. After purification and concentration, the plutonium is transformed back into plutonium oxide, packaged in sealed containers and stored. It is then intended for the fabrication of MOX fuels in the Orano plant in Marcoule (Melox). The effluents and waste produced by the operation of the plants The fission products and other transuranic elements resulting from reprocessing are concentrated, vitrified and packaged in CSD-V. The pieces of metal cladding are compacted and packaged in standard compacted waste packages (CSD-C). These reprocessing operations also use chemical and mechanical processes, the operation of which generates gaseous and liquid effluents as well as solid waste. The gaseous effluents are released mainly when the fuel assemblies are sheared and during the dissolution process. These gaseous effluents are treated by washing in a gas treatment unit. The residual radioactive gases, particularly krypton and tritium, are checked before being discharged into the atmosphere. The liquid effluents are treated and usually recycled. After verification and in accordance with the discharge limits, certain radionuclides, such as iodine and tritium, are sent to the marine outfall. The other effluents are routed to on-site packaging units (solid glass or bitumen matrix). The solid waste is conditioned on-site, either by compacting, or by encapsulation in cement, or by vitrification. The solid radioactive waste from the reprocessing of spent fuel assemblies from French reactors is, depending on its composition, either sent to the lowlevel and intermediate-level, short-lived waste (LLW/ILW-SL) repository at Soulaines (see chapter 14) or stored on the Orano site at La Hague, pending a final disposal solution; this is notably the case for the CSD-V and CSD-C, for which final disposal is envisaged in the planned Cigéo project (see chapter 14). In accordance with Article L. 542-2 of the Environment Code, the radioactive waste from the reprocessing of spent fuel assemblies from abroad, is sent back to the producer country. It is however impossible to physically separate the waste according to the fuel from which it originates. In order to guarantee an equitable distribution of the waste resulting from the reprocessing of the fuels of its various customers, the licensee has proposed an accounting system that tracks the entries into and exits from the La Hague plant. This system, called “Exper System”, was approved by the Order of the Minister responsible for energy of 2 October 2008. 1.4 “Fuel cycle” consistency in terms of nuclear safety and radiation protection The “nuclear fuel cycle” comprises the fabrication of the nuclear fuel used in the nuclear power plant reactors, its storage, its reprocessing after irradiation and management of the resulting waste. Several licensees are involved in the cycle: Orano, Framatome, EDF and the French national radioactive waste management agency (Andra). ASN monitors the overall consistency of the industrial choices made with regard to fuel management and which could have consequences for safety. On 18 October 2018, ASN issued its opinion 2018-AV-0316 on the “2016 Cycle Impact” dossier, jointly drafted with the industrial stakeholders in the “cycle”. This dossier presents the consequences for each step in the “fuel cycle” of the strategy implemented by EDF for use of different types of fuels in its reactors, different energy mix scenarios envisaged by the Multiyear Energy Programme (MEP), or the operating contingencies of the plants involved in the “fuel cycle”. It underlines the need to anticipate any strategic change in the functioning of the “fuel cycle” by at least ten years so that it can be designed and carried out under controlled conditions of safety and radiation protection. It is a question for example – given the incompressible development times for industrial projects – of ensuring that the needs for the creation of new spent fuel storage facilities or for new transport packaging designs are addressed sufficiently early. In December 2020, together with Framatome, Orano and Andra, EDF updated its “fuel cycle” outlook according to energy mix scenarios consistent with the Multi-year Energy Programme published in April 2020. In the light of this outlook, saturation of spent fuel storage capacity could be reached in 2030, or even 2029. EDF also announced in 2020 a postponement of the commissioning of its centralised storage pool project, now scheduled for 2034, which means that countermeasures are needed to deal with the delay in this project: these countermeasures are the densification of the storage pools at La Hague, dry storage of spent fuels and greater use of MOX fuel in the reactors. ASN recalls that none of these countermeasures has the same safety advantages as the centralised storage pool project, which to date remains the reference solution with no alternative equivalent in terms of safety. After the malfunctions concerning certain steps in the “fuel cycle”, which had appeared and became worse in 2021, the situation in 2022 remains fragile: ∙ The Melox plant is still experiencing difficulties in producing MOX fuel of the required quality and quantities expected. These difficulties are leading to the production of a large quantity of radioactive materials containing plutonium unsuitable for use as fuel in reactors, qualified as “MOX scrap”, which is then stored in the La Hague plant, either in powder form, or in the form of fuel assemblies. ∙ An action plan has been implemented by Orano since 2019 to overcome the production difficulties at Melox. The use of depleted uranium powder, produced by the “wet process approach” was qualified in September 2022. Output by the Melox plant was thus slightly higher than in 2021, when it was very low. The production of MOX scrap was also kept down. The use of this powder prevents the situation from being further degraded, pending the use of a “wet process” uranium powder from a new unit called “New Wet Process” (NVH) in Orano’s Malvési plant. This unit is currently under construction, with a view to the “wet process” production of depleted uranium at the end of 2023. 324 ASN Report on the state of nuclear safety and radiation protection in France in 2022 • 11 • “Nuclear fuel cycle” facilities 11
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