Selected topics of molten fluorides in the field of nuclear engineering

A new reference electrode in fluoride melts and a new concept for a spent zircaloy wastes treatment using a mixture of fluoride and chloride melt are proposed. Electrochemical formation of Au2Na on Au wire in a LiF–KF–NaF shows the equilibrium potential of the reaction: 2Au + Na+ + e− = Au2Na at 0.535 V vs. K+/K in LiF–NaF–KF eutectic melt at 773 K. The (Au2Na + Au) electrode demonstrates excellent characteristics as a reference electrode in terms of reproducibility, stability and reversibility. LiF–LiCl–KCl melt enhances dissolution and deposition rate of zirconium, which enable us to develop a new decontamination process for a spent zircaloy. Electrochemical decontamination using LiF–LiCl–KCl melt is experimentally achieved a clearance level.