5. Chemical exchange separation processes

The slight difference between the chemical properties of two isotopes of the same element makes it possible to separate these isotopes by reversible chemical exchange. Nobel Prize-winner U.C. Urey was the first to use this method in 1935 for the light elements (H, B, C, N). For uranium, two processes have been studied: the Japanese process uses exchange between valence ions IV (uraneous) and VI (uranyl), while the French process uses exchange between valence ions III and IV.