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FEDERAL REPUBLIC OF GERMANY n 7 5 i 4 EGGENSTEIN-LEOPOLDSHAFENRecent trends in reprocessing of spent LWR-fuel necessitate improved neptunium decontamination in uranium purification cycles.For the uranium purification cycles of the WAK plant and the EUROCHEMIC plant, respectively, the time dependent performance of the 2D-extractors has been calculated using the VISCO program for the mathematical modelling of solvent extraction processes. Results have been validated using dataacquiredin laboratory-scale extraction facilities and in the plant.Intercycle evaporation and thus high uranium concentration in the aqueous feed solution results in a high organic-to-aqueous flow ratio within the extraction part of the 2D-extractor. The required neptunium decontamination is achieved by allowing a considerable amount of uranium to leave the extractor with the aqueous raffinate rather than with the organic product stream. Thereby an increased amount of process control is required. aqueous raffinate stream by feeding diluted uranium solutions, received from the preceeding backextraction step, to the 2D-extractor. Then the uranium yield of the extraction step is high, while the amount of process control required is low.AS an alternative, neptunium can be sent directly to the Copyright 0 1984 by Marcel Dekker, Inc.

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