To develop an advanced technology which uses compacted equipment and generates less radioactive waste for reprocessing spent nuclear fuels, a new aqueous reprocessing system based on ion exchange separation has been studied. This process consists of (1) Pd removal by selective adsorption; (2) electrolytic reduction for the valence adjustment of U and some fission products such as Tc and Ru; (3) recovery of U, Pu and Np by anion exchange; and (4) separation of the long-lived minor actinides (Am, Cm) by extraction chromatography. For this process, we have prepared several novel anion exchangers and some chelating extraction-resins which are immobilized in porous silica particles. In this article, studies on the adsorption characteristics of various oxidation states of typical elements (nuclides) in spent nuclear from nitric acid solution with the anion exchangers are reviewed. Separation behavior of the nuclides in practical spent fuel solutions is demonstrated using the anion exchange columns. The results indicate that the proposed U and Pu recovery process is essentially feasible, although further works such as scale-up testing are needed.

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New adsorption materials for the metal ions were synthesized with β-diketones retained on the octadecyl-group bonded to silica gel (C18) to capture the metal ions. The β-diketones such as TTA and BFA were used as reagents for separation of the metal ions. The reaction ability of materials (Silica gel, C-18, TTA-C18 and BFA-C18) was evaluated by solid-liquid distribution behavior. It was found that these materials have adsorption ability with metal ions at pH 2-6. On the other hand, silica gel and C-18 could not react with metal ion at pH 2-5.5. It was confirmed that these metal ions were adsorbed on these materials by an ion-exchange reaction, and their selectivity series was Cu²⁺+>Ni²⁺>Co²⁺=Zn²⁺>Mn²⁺. The mutual separation ability was found to be better than that of reported inorganic ion-exchangers such as dihydrogen tetratitanate hydrate fibers. BFA-C18 had an especially high selectivity for Cu²⁺.

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A Chelating fiber containing an amidoxime group as a chelate-forming group was prepared by radiation-induced cograft polymerization of acrylonitrile and methacrylic acid and subsequent conversion of the produced cyano group into the amidoxime group. The effect of repeated use of monomers for radiation-induced graft copolymerization on the composition of the graft chain and its adsorption capacity for metal ions was determined. The degree of cografting decreased by as low as 10% at the fourth cycle of cografting, compared with an initial degree of cografting of 170%, because the amount of homopolymer formed in cografting was negligibly small at 0.15g/L of the monomer solution. The repeated use of monomers did not affect the amidoxime group density and the adsorption capacities of zinc and cadmium ions, resulting in the cost reduction of the preparation of the chelating fiber.

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Computational chemistry is a powerful tool that can provide increased insight and understanding of many complex topics. The rapid advances in computer hardware and software for computational chemistry over the last decade allow meaningful chemistry calculations to be performed on standard desktop computers. Chemists and chemical engineers now have an additional tool available that is complementary to traditional experimental and theoretical techniques. This paper focuses on how we utilize the advantage of molecular modeling and related computational techniques to prepare the separation materials for antimony (III) .

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