The removal of high heat emitters from spent fuels allows to reduce the volume necessary for a safe storage in deep repository. Some of these isotopes can also be recycled, for instance 241Am as fuel for fast-breeder reactors and 137Cs as a gamma source (radiotherapy, sterilization). A new process called CHON-UNEX has been recently proposed, whose ligands and diluents are composed of only C, H, O and N elements so that the effluents can be eventually vaporized and do not form secondary wastes. It consists in a co-extraction of all high heat emitters followed by successive stripping steps to enable the recycling of these elements. The Sr, Am and Ln extractant is a diglycolamide (DGA) that also serves as modifier for the Cs extractant, a calixarene crown-ether (CC) insoluble in kerosene.
At first, the Ph.D. student will study several commercially available DGAs in combination with 2 CCs to assess their extraction efficiency and selectivity, followed by the determination of the speciation and the supramolecular assemblies of these systems by various analytical tools. Then, the student will perform the selective stripping of Am by phenanthroline-based hydrosoluble ligands previously tested on Lns by an other student.
The student will eventually gain knowledge on the nuclear fuel cycle, hydrometallurgy and analytical tools that can lead to pursue academic work or to a job in the hydrometallurgy industry.
The candidate is M.Sc. with chemistry as major. A solid basis in analytical chemistry is recommended.