Actinide removal from highly active nuclear waste solutions by solvent extraction

This paper related to studies on actinide separation from highly active nuclear wastes presents the main experimental results obtained by solvent extraction of a solution simulating the radioactive effluents (HAW) produced during the first extraction cycle of the 'Purex' process. These batch experiments have shown that the decontamination factors required for transuranic elements with high radiotoxicity (103 for americium, curium, plutonium and 10 for neptunium) can be obtained by using di (α-ethyl-hexyl)-phosphoric acid (HDEHP) or tributyl phosphate (TBP) as extracting solvents and by assuming that actinides exist on extractable forms in solution. Two separation schemes involving these solvents have been proposed. Because in any actinide separation process it may be necessary to include a decontamination step for the removal of α-emitting elements from the various solid wastes produced by the reprocessing step, two possibilities have been considered in each scheme. In the first one, special treatments are used to recover plutonium sorbed on the precipitate produced by the denitration of the HAW solution. This operation is required to remove trivalent actinides. The second possibility involves a complete preliminary plutonium extraction