COMPARISON OF DIALKYL PHENYLPHOSPHONATES WITH TRI-n-BUTYL PHOSPHATE IN NITRATE SYSTEMS: EXTRACTION PROPERTIES, STABILITY, AND EFFECT OF DILUENT ON THE RECOVERY OF URANIUM AND THORIUM FROM SPENT FUELS

摘要

Di-n-butyl phenylphosphonate (DBPP) and di-sec-butyl phenylphosphonate (DSBPP) were investigated as possible substitutes for tri-n-butyl phosphate (TBP), the reagent presently employed in the reprocessing of uranium and thorium nuclear reactor fuels. The phenylphosphonates form complexes with uranium and thorium that are mostly insoluble in the aliphatic solvents commonly used as diluents for TBP but that are soluble in other diluent types, for example, aromatics and CC14. Therefore, the phosphonate were diluted with aromatics and the TBP was diluted with both aliphatic and aromatic diluents.