Determination of uranium and rare-earth metals separation coefficients in LiCl-KCl melt by electrochemical transient techniques

Kuznetsov, S. A.*; Hayashi, Hirokazu ; Minato, Kazuo ; Gaune-Escard, M.*

The knowledge of separation coefficients of actinides and rare-earth metals is important for developing pyrometallurgical process of spent nuclear fuel. Electrochemical experiments were carried out at 723-823 K to estimate separation coefficients in LiCl-KCl eutectic melt containing uranium and lanthanum trichlorides. Uranium and lanthanum separation coefficients is calcurated with the voltammetric peak potentials of U (III) and La (III), their concentration in the melt and kinetic parameters for U(III) discharge such as diffusion coefficients, and standard rate constants of charge transfer. The diffusion coefficients of U (III) were determined by some electrochemical measurements. The standard rate constants of charge transfer for electroreduction of uranium U(III) +3e =U were calculated by impedance spectroscopy method.