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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After an overview of the applications of ion‐exchangers in reprocessing, our present investigations using macroporous resins are reported. A polystyrene‐divinylbenzene tributylphosphate copolymerisate resin (Levextrel‐TBP Bayer AG.) as stationary phase was used for the extraction chromatography of actinides. Distribution coefficients of U, Pu, Np, Am in 0.1 to 6 M HNO3 solutions were measured. A loading capacity up to 140 g Pu/1 resin was achieved in equilibrium with solutions containing 20 g Pu/1 and 6 M HNO3. Elution using 3 bed volumes of 0.3 M HNO3 at 50°C and a flow rate of ca. 1 cm/min removed more than 99.5% of Pu from the resin. A process for separation of plutonium from americium and fluoride was developed. Studies on the removal of tributyl‐ and dibutyl phosphate from aqueous product and waste streams by macroporous styrene‐divinylbenzene copolymers (without functional groups) are described. The process developed is routinely used for purification of radioactive solutions in the laboratory‐scale reprocessing facility MILLI in Karlsruhe. Loadings of 200 g TBP per liter resin and separation of TBP to less than 2ppm in the aqueous effluent solutions can be achieved.

Die Aufbereitung bestrahlter Kernbrennstoffe mit Dibutyläther als Extraktionsmittel hat gegenüber dem Purex‐Verfahren (Extraktion mit Tributylphosphat) einige Vorteile: Höhere Dekontaminierungsfaktoren, geringere Neigung zur Emulsionsbildung und somit einfachere Handhabung in den Extraktionskolonnen und Mixer‐Settlern, kleinere Volumina an Waschphase bei der Rückwäsche des uranhaltigen Produkts aus der Solventphase, weitgehender Verzicht auf eine Reinigung der Solventphase (Wäsche mit verdünnter Salpetersäure genügt). Als Nachteil ist hingegen die Anwendung von Calciumnitrat als Aussalzagens aufzufassen, da dieses kaum rückgewinnbar ist und daher den Feststoffgehalt der radioaktiven Abwässer bedeutend erhöht.