Cyclic Voltammetry on Zr, Sn, Fe, Cr and Co in LiCl-KCl Salts at 500oC for Electrorefining of Irradiated Zircaloy-4 Cladding

Abstract

To achieve a better understanding of Zircaloy-4 electrorefining in LiCl-KCl at 500 degrees C, redox behaviors of Zr, Sn, Cr, Fe and Co, were examined by cyclic voltammetry using tungsten working and counter electrode. Zr metal can be produced from Zr4+ through two step reduction and ZrCl is generated as an intermediate product. As ZrCl4 concentration decreases, ZrCl would be easily reduced into Zr metal. In addition, Zr2+ formation would be unlikely at low ZrCl4 concentration. The redox reactions of the other elements are much simpler than Zr. The reduction of Zr4+ into ZrCl was close to irreversible but the reduction reactions of the other elements are close to reversible. The diffusion coefficients and apparent reduction potentials were calculated using equations for a reversible or irreversible reaction. The diffusion coefficients are in the order of 10(-9) m(2)/s and Zr is less reductive than other elements.