Role of diluents in the comparative extraction of Th(IV), U(VI) and other relevant metal ions by DHOA and TBP from nitric acid media and simulated wastes: Reprocessing of U-Th based fuel in perspective

Keeping reprocessing of U-233-Th based fuel in perspective, solvent extraction of Th(IV), U(VI) and some relevant metal ions has been carried out from nitric acid media and simulated high-level waste (HLW) typical of a fast-breeder reactor using dihexyloctanamide (DHOA) in commercially available alternate diluents, viz. Solvesso 100 and ShellSol D70. Acid uptake constant (K-H) and distribution ratios (D) of metal ions as a function of nitric acid, thorium ion and extractant concentrations are determined. Slope-analysis results showed various types of species extracted into the organic phase. For comparison, a similar set of experiments were carried out with tri-n-butyl phosphate (TOP) in both diluents. A few clear and interesting trends were observed in the variation of D values of metal ions. Interference of other relevant metal ions likely to get co-extracted along with Th(N) and U(VI) was also studied by ICP-AES using a simulated HLW. (C) 2015 Elsevier B.V. All rights reserved.