ION-EXCHANGE BEHAVIOR AND SEPARATION OF ACTINIDES IN VARIOUS OXIDATION-STATES ON CATION-EXCHANGERS IN DILUTE HF

The distribution coefficients of Th, Pa, U, Np, Pu, Am, and Cf, in add ition to Zr-Nb between the cation-exchanger Dowex-50 and HF solutions as a function of [HF] (0.01-1.0 M) and the presence of an oxidizer (Pb O2) on the resin are determined. The basic principles of the behavior of the actinides are found. Suggestions are made about the sorption me chanism from HF solutions of these elements in various oxidation state s on the cation exchangers. Simple effective methods are presented for the separation of trivalent TPE from the other actinides (Pa, U, Np, Pu) and for the separation of certain pairs of actinides in higher oxi dation states using small cation-exchange columns and 0.01-0.5 M HF as eluents. Continuous generation of isotopically pure Np-239 and Pa-233 is possible from the parent Am-243 and Np-237, respectively. A method is developed for isolating and purifying Pa-231 and its radioactive d ecay products Ac-227 and Th-227 on a single cation-exchange column.