Actinides Recovery From A Molten Chloride Salt

Abstract:

Pyrochemical separations technology using high-temperature molten salt and metal media shows potential as a component of an overall separation and transmutation strategy for long-lived radionuclides. It could also be used for advanced fuel cycles associated with new types of reactors (Gas Cooled Reactor, Molten Salt Reactor, Fast reactor with metallic fuels, Accelerator Driven Systems).A pyrochemical process has been developed at the laboratory scale. The separation between the actinides and the fission products is operated by liquid-liquid extraction between a molten fluoride salt and a liquid metallic aluminum phase. Actinides are then back-extracted from the aluminum phase in a molten LiCl-CaCl2 salt at 700°C. Among the different steps of the process that still need to be studied is the head-end step with the recovery of the actinides from the molten chloride salt under an oxide form.The use of carbonate salts that deliver O2- ions and induce the actinides precipitation under oxide and oxychloride forms is known. However this method is increasing the solvent volume and therefore the waste production.Another method consists in precipitating the actinides with a carrier gas that brings O2- ions. This paper presents the results of our back-extraction and precipitation studies from the molten LiCl-CaCl2 salt at 700°C with lanthanides and actinides. We first describe our methodology used to monitor both reactions and to determine the reaction yield. The characterization of the different phases obtained after the precipitation and the calcination is then presented. As a conclusion, the viability of this process is discussed.

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