Key words: supercritical fluid extraction, liquid and supercritical carbon dioxide, spent nuclear fuel reprocessing, complexation, tributyl phosphate, aqueous Fe(III) nitrate solutions
Solubility of UO2(NO3)2-tributyl phosphate (TBP) complex in liquid and supercritical (SC) carbon dioxide as a function of temperature and pressure is measured. This complex is formed during the dissolution of uranium oxide in two-phase system consisting of aqueous iron nitrate solution and liquid or supercritical CO2 saturated with TBP. Kinetics of ceramic UO2 dissolution in such two-phase solvent is studied. The feasibility of the recovery of uranium from spent oxide nuclear fuels via its dissolution in sub-acid iron nitrate aqueous solutions accompanied by simultaneous extraction of the above mentioned complex into «TBP — SC-CO2» phase is demonstrated.