Separation characteristics of a spent fuel surrogate in the molten salt electrorefining process

The electrorefining experiments with an anode composed of U, Y, Gd, Nd and Ce were carried out in the KCl–LiCl and LiF–NaF–KF (FLINAK) eutectic melt at 500 and 600 °C, respectively. Uranium was the major component in the cathode deposits, and the separation factors of the uranium with respect to the rare earths (REs) are nearly the same in both electrolytes. REs concentrations in the molten salts and cathode deposits increased sharply at above 1.9 V, which is the decomposition voltage of the REs. The current efficiency was inversely in proportion to the applied voltage in the range of 1.0–1.9 V (versus iron and Ni). The dependency of the applied voltage on the current efficiency as well as the deposition rate was discussed in terms of the microstructural feature of the deposit.