Abstract: A method of dissolving in an ionic liquid a metal in an initial oxidation state below its maximum oxidation state, characterized in that the ionic liquid reacts with the metal and oxidizes it to a higher oxidation state. The initial metal may be in the form of a compound thereof and may be irradiated nuclear fuel comprising UO2 and/or PuO2 as well as fission products. The ionic liquid typically is nitrate-based, for example a pyridinium or substituted imidazolium nitrate, and contains a Bronstead or Franklin acid to increase the oxidizing power of the nitrate. Suitable acids are HNO3, H2SO4 and [NO+]. Imidazolium nitrates and certain pyridinium nitrates form one aspect of the invention.

Abstract: A process is disclosed for the treatment of a solvent which has been used in nuclear fuel reprocessing or uranium ore purification, the solvent comprising an organophosphate ester and a hydrocarbon diluent. The process includes distilling the solvent under reduced pressure to remove substantially all the diluent and a major proportion of the organic ester, converting organophosphate to inorganic phosphate and encapsulating the residual material.