Isotope separation factor in uranium enrichment using ion-exchanger

The uranium enrichment by redox chromatography using an ion-exchanger was studied. As a result, the isotope separation factor in this process is smaller than that determined from the equilibrium constant of solution. There exist three kinds of equilibrium reactions in this process: isotope equilibrium by electron exchange, that by adsorption/desorption of complexes (U⁴⁺, UO₂²⁺) to resin, and phase equilibrium of U⁴⁺ and UO₂²⁺. We made it clear that small isotope separation factor mainly dependes upon the adsorption characteristics of complexes (U⁴⁺, UO₂²⁺) to the ion-exchanger among those reactions. On the other hand, computer simulation of chromatographic development was carried out to analyze the details of experimental results theoretically. The separation column was hypothetically divided into equilibrium stages, and the equilibrium condition of each stage was simulated. A comparison between the calculated and observed separation factors was made. By this theoretical treatment, it was clarified that the separation factor decreases drastically in the region where development length is short. (author)