Electrochemical Properties of Uranium and Zirconium on Solid and Liquid Electrodes in 3LiCl–2KCl Based Melts

Abstract

Spent nuclear fuel (SNF) reprocessing for fast neutron reactors can be organized by employing high temperature pyrochemical methods. Fused salts and liquid metals or alloys are the working media in the pyrochemical processes. Electrochemical deposition and electrochemical separation of uranium from fission products is an important stage of pyrochemical SNF reprocessing. Reliable data on electrochemical properties of uranium and fission product elements are required for development and optimization of the pyrochemical processes. Uranium and zirconium have very close electrode potentials and separating uranium (fissile material) from zirconium (fission product) is an important and difficult to solve task in the pyrochemical reprocessing. This work devoted to studying electrochemical properties of zirconium and uranium employing cyclic voltammetry method in 3LiCl–2KCl eutectic based melts containing uranium and zirconium chlorides. Various types of electrodes were tested to determine uranium and zirconium deposition potentials aiming to finding the cathode material with the largest difference of uranium and zirconium potentials. Tungsten was used as a solid cathode, and liquid alloys based on Ga, Al, Zn, Sn and their mixtures were tried as low-melting liquid cathodes. Electrochemical measurements were made in temperature range of 450–800 0C. On the basis of the results of electrochemical measurements the possibility of separating uranium and zirconium employing liquid metal alloys was elucidated. Acknowledgements: This work was supported by the Russian Science Foundation (project No 17–73–20156).