Ultrasound-enhanced dissolution of UO2 in supercritical CO2 containing a CO2-philic complexant of tri-n-butylphosphate and nitric acid

Application of ultrasound can significantly enhance the dissolution Of UO2 Powders placed on small glass beads in supercritical fluid CO2 Using a CO2-Soluble tri-n-butylphosphate (TBP)/ HNO3/H2O complexant as an extractant. The amount Of UO2 dissolved in CO2 for a 20-min dynamic extraction at 323 K and 15 MPa can be increased by an order of magnitude with sonification compared to experiments without sonification. The application of ultrasound probably contributes to the transfer of locally concentrated UO2(NO3)(2).2TBP from the surface of glass beads into supercritical fluid CO2. This ultrasound-aided process for direct dissolution Of UO2 in supercritical fluid CO2 that requires no aqueous solutions and organic solvents may have important applications for reprocessing of spent nuclear fuels and for treatment of certain nuclear wastes.