Currently, in France, UOx fuel cladding is made of zirconium and tin or niobium based alloys. At the end of the use of nuclear fuels in the reactor, the fuel claddings contaminated with actinides (An), fission products (FP) and activation products (AP) are stored awaiting their storage in a geological site.
It is planned to decontaminate these claddings, once the spent fuel has been removed, to make them less radioactive, with the aim of decategorizing them.
Studies on radioactive sheaths have shown that the use of a fluoride-based slag allows decontamination of An and FP towards the slag. The scientific obstacle lies in the decontamination in AP, and more precisely in the preliminary stage of Zr/Nb separation.
In addition, the management of fluoride slags should be avoided due to the strong tendency of fluorine to corrosion. The use of oxide slags would be an alternative way to be privileged, constituting the second challenge of this research project.
The objectives of the post-doctorate will initially be to formulate slags. Then, Zr alloy decontamination, Zr/Nb separation and separation of activation products will be studied.
The experiments developed, in a non-radioactive laboratory, will be based on a literature review carried out by the post-doc and on the results of thermodynamic calculations performed at the LM2T of CEA Saclay.
The missions of the post-doc will be to develop slags according to the operating conditions that he/she will have defined (composition, temperature), to characterize them using physico-chemical analyzes (SEM/EDS, XRD, TDA/TGA) and to test them, in the presence of duct sections, for decontaminating melting. The post-mortem analysis will allow to assess their decontamination capacity and to optimize, if necessary, the interactions at the interfaces and/or their chemical composition.