Electrochemical Investigation of Exchange Current Density of Uranium and Rare-earths Couples (M3+/M-0) in LiCl-KCl Eutectic Electrolyte

Abstract

The objective of this work is to use electrochemical techniques to quantify the electrode reaction rate of some rare-earth elements and uranium in a LiCl-KCl eutectic electrolyte at 500 degrees C. The exchange current densities of the oxidation-reduction couples of M3+/M-0 (La3+/La-0, Ce3+/Ce-0, Pr3+/Pr-0, Nd3+/Nd-0, Gd3+/Gd-0, Y3+/Y-0, U3+/U-0) on a tungsten electrode were measured by applying a linear polarization resistance technique. A region of linear dependence of potential on applied current could be found to describe the reaction rate of oxidation-reduction system. From these measurements, the estimated exchange current density was 0.38 mA/cm(2) for uranium, and was within the range of 0.27 to 0.38 mA/cm(2) for rare-earth elements.