Dissolution of oxide nuclear fuel in subacidic iron(III) nitrate solutions and extraction of uranium from it with tributyl phosphate-containing supercritical carbon dioxide

The solubility of the uranyl nitrate complex with tributyl phosphate (TBP) in liquid and supercritical carbon dioxide (SC-CO 2 ) has been measured as a function of temperature and pressure. This complex is formed upon the dissolution of uranium dioxide in the two-phase system consisting of aqueous iron(III) nitrate and TBP-saturated liquid or supercritical CO 2 . The kinetics of the dissolution of ceramic UO 2 in such a two-phase solvent is studied. It has been shown that uranium can be extracted in the presence of TBP-containing supercritical CO 2 via the dissolution of spent oxide nuclear fuel in subacidic iron(III) nitrate solutions with the simultaneous extraction of the uranium complex into the TBP-SC-CO 2 phase.