* See glossary page 34 A new project will be able to manage waste for which there is as yet no disposal solution*. In addition, thanks to technical progress, the radioactive wastes could be made less dangerous or less numerous. Overview of the potential solutions for the future. POTENTIAL SOLUTIONS for the future THE LLW-LL WASTE REPOSITORY PROJECT Since 2008, Andra has been studying a project for a LLW-LL waste repository. The project concerns a waste repository* in a clay layer at a depth of about thirty metres, at Vendeuvre-Soulaines, in the Aube département. It would be able to isolate the waste from human activity and erosion, limit the circulation of water in the repository and delay the transfer of radionuclides* to the biosphere. At the beginning of 2024, Andra will produce a file presenting the technical and safety options chosen for this facility. NUCLEAR FUSION In the fission process, heavy atoms are broken into several pieces by bombarding them with neutrons. In the fusion process, the opposite happens: matter is compressed with such force that two light atoms merge into a single heavier atom. A fusion reactor would not therefore produce the same radioactive waste as the current NPPs (fission products*, actinides*, etc.) but lower level tritiated waste with a shorter lifetime. However, the production of electricity using nuclear fusion still has to overcome significant technological hurdles. FAST-NEUTRON REACTORS (FNRS) This type of reactor produces fission reactions from a wide variety of fuels, spent fuels* in particular. For example, they can use the plutonium produced by the existing fleet of Pressurised Water Reactors (PWRs). They are also capable of running on natural uranium, with an energy efficiency higher than the current fleet, thereby using all of the natural uranium. Finally, in certain conditions, some FNRs are able to transform the minor actinides* (americium, neptunium and curium) contained in high level radioactive waste into shorter lived elements. This transformation, called “transmutation*”, would reduce the emission of heat and the inherent radiotoxicity of the ultimate waste. SEPARATION/TRANSMUTATION Separation/transmutation processes aim to isolate and then transform the long-lived radionuclides in radioactive waste into shorter-lived radionuclides or even stable elements. This would have an impact on the sizing and design of the repository, by reducing the thermal power, the harmfulness of the waste emplaced and the volume of the repository. ASN considers that if transmutation studies were to be continued, they should cover the radioactive substances currently categorised as materials, or the waste produced by a future fleet of reactors. RECYCLING OF VERY LOW-LEVEL WASTE (VLLW) Recycling of some of the VLL metal materials would be one way of optimising waste disposal capacity by reducing the quantities of waste to be disposed of, and thereby the corresponding land artificialisation. This would also lead to savings in raw materials, which would be replaced by the recycled waste. In concrete terms, this involves melting the waste, eliminating the contaminated fraction and using it to manufacture objects or structures. 24 • Les cahiers de l’ASN • May 2024
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