Electrolysis of burnup-simulated uranium nitride fuels in LiCl-KCl eutectic melts

Abstract

The electrochemical behavior of burnup-simulated uranium nitride fuels containing representative solid fission product elements, UN+Mo (Mo = 2.84 wt%), UN+Pd (Pd = 4.6 wt%) and (U, Nd)N (NdN = 8.0 wt%), was investigated in the molten LiCl-KCl eutectic salt with 0.54 wt% UCI3 in order to clarify the effects of fission products on the dissolution of actinide nitrides and the behavior of FPs in the electrorefining of spent nitride fuel. The rest potentials of burnup-simulated UN pellets were similar to that of pure UN. The electrochemical dissolution of UN began at about -0.75 vs Ag/AgCl reference electrode in all samples as well as that of pure UN. After the electrolyses at the constant anodic potential of -0.65-0.60 vs Ag/AgCl, most of UN was dissolved into LiCl-KCl as UCI3 at the anode, and U was recovered in the liquid Cd cathode in all samples. Furthermore, Nd was dissolved at the anode and accumulated into LiCl-KCl as NdCl3, while Mo and Pd were not dissolved but remained at the anode. ©Atomic Energy Society of Japan. © Atomic Energy Society of Japan.