France's National Assessment Board (CNE) took the view in its final report that the conditioning of primary packages of high-level (HLW) and intermediate-level (ILW-LL) waste was well understood and that the field had reached industrial maturity. These primary packages are made up of vitrified waste and compacted waste produced at La Hague. The CNE believes that the conditioning of both categories of waste is appropriate for their geological disposal, provided that containers are also added.
Adding containers means putting primary packages and other types of radioactive packages into suitable canisters and containers to form a separate barrier, which is essential for safety during both storage and disposal.
Demonstrators have been made for storage containers for primary packages of intermediate-level waste (ILW-LL), high-level waste (HLW) and spent fuel assemblies. Their durability will be studied in accordance with the requirements of the long-term storage facilities planned to accommodate this waste.
Teams at CEA (the French Alternative Energies and Atomic Energy Commission) have designed separate solutions for packages that do not emit heat and for those that do - spent fuel assemblies and vitrified waste packages. For packages that do release heat, a model-based study of their durability and ability to remove heat is in progress.
With packages of intermediate-level long-lived waste (ILW-LL), tests have shown that the radioelements they contain could not be recovered for transmutation and that they are therefore the final waste (they only account for a few % of the total activity). Since these primary packages do not release any heat, the proposal was made to place them in durable concrete containers that could be used both for storage and disposal. Demonstrators for these dual-use containers have been made by CEA and ANDRA.
Sweden, which will be one of the first nations to bury its spent fuel, has chosen to use large copper containers for the assemblies taken out of its reactors. Copper has been chosen for its corrosion resistance. These containers, when full, will weigh 25 tonnes.
Finally, the containers for packages of vitrified high-level waste would be similar in design to those for spent fuel assemblies. For example, a CEA project is looking at containers that can hold six UC-V (CDS-V) packages.
However, in the CNE's view, there is still further research and work to be done on the containers to be used for waste packages and spent fuel assemblies. Their specifications have not yet been defined.
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