Abstract: | The extreme limits for 235U/238U % at ambiant temperature were determined experimentally with a long time band displacement process (almost 1 year) using the isotope exchange reaction between U(IV)resin and U(VI)solution. These limits are 0.738 and 0.712, considering 235U/238 = 0.725% for natural uranium. The redox reactions, allowing the band displacement were: 1) in front of the band is the reduction of U(VI) in solution by a cathionic resin in Ti(III)-form; 2) in the tail of the band is the oxydation of U(IV) in resin by a solution containing Fe(III) ions. |