イオン交換体による同位元素分離に関する基礎的知見, (IX)

Abstract

Breakthrough experiments were carried out to study ion exchange separation of uranium isotopes. Four kinds of solutions containing natural uranium (mole fraction of 235U 0.7200×10-2), (1) 0.05M TnOA/benzene solution saturated with U (IV)-chloro complex, (2) mixture of 0.05M TnOA/benzene solution saturated with U (IV)-chloro complex and 0.05M TnOA/benzene solution saturated with U (VI)-chloro complex, (3) 0.05M TBP/benzene solution with U (IV)-chloro complex, (4) mixture of 0.05M TBP/benzene solution saturated with U (IV)-chloro complex and 0.05M TBP/benzene solution saturated with U (VI)-chloro complex, were passed through 100 cm long, 1.3cm diameter anion exchange resin columns until the composition of the effluents became equal to that of the feed solutions.Near the front of the breakthrough of the solution (4) above, the 235U was found enriched to 0.7324×10-2 (enrichment factor 1.017), while in the case of the solution (2), 235U was depleted to 0.7107×10-2 (enrichment factor 0.987).From the total amounts of 235U enriched or depleted by these breakthrough experiments, single process ion exchange separation factors of uranium isotopes were estimated to be 1.000000 for the solution (1), 1.00033 for the solution (2), 0.99989 for the solution (3), and 0.99988 for the solution (4).Based on these data, the apparent equilibrium coefficients of the electron exchange reaction, 235U (VI)+238U (IV)_??_238U (VI)+235U (IV)were estimated to be 1.0010 and 1.0013 for TnOA/benzene and TBP/benzene systems, respectively. These values are smaller than the value of 1.0020 obtained for 8M hydrochloric acid in the previous paper. The apparent equilibrium coefficient of the electron exchange reaction in the anion exchange resin (Dowex 21 K) was estimated to be 1.00101.0013.