Chronopotentiometric measurements were used to study the diffusion of U3+ and U4+ ions in eutectic melts. When the U ions were added as UCl3, the diffusivity of U3+ (0.016 to 0.40mol/l) at 450C was equal to 4.8 x 10-6cm2/s. The activation energy, at temperatures ranging from 375 to 530C, was 8.7kcal/mol. The corresponding values for U4+ were 6.6 x 10-6cm2/s and 9.8kcal/mol. When the U ions were added as UF4, the diffusivity of U4+ (0.012 to 0.08mol/l) at 450C was equal to 1.3 x 10-5cm2/s. The activation energy, at temperatures ranging from 415 to 550C, was 8.4kcal/mol.

Chronopotentiometry in Molten Chlorides. Application to the Study of the Electrochemical Properties of U and Pu in LiCl-KCl. A.Leseur: Commission d’Energie Atomique Report CEA-R-3793, 1969