Rotating Disk Electrode Study of Sm(III)/Sm(II) in LiCl-KCl Eutectic Molten Salt

Abstract

Understanding the redox reactions of fission products in molten salts is crucial for developing pyroprocessing techniques for used nuclear fuel. A rotating disk electrode is useful for investigating the electrochemical reactions with controlled mass transfer conditions, but its application has been limited in high-temperature corrosive molten salts. This study employs a tungsten rotating disk electrode to measure the electrochemical and kinetic properties of the Sm(III)/Sm(II) redox reaction in a LiCl-KCl eutectic molten salt. The properties of the Sm(III)/Sm(II) redox reaction, including diffusion coefficients, exchange current densities, charge transfer coefficients, activation energies, and Tafel slopes, were determined over a temperature range of 723-803 K using limiting currents in linear sweep voltammetry at various rotating speeds and mass transfer-corrected Tafel plots. The kinetic parameters obtained using the rotating disk electrode system can be useful for optimizing the design of pyroprocessing techniques.