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

Sato, Takumi  ; Iwai, Takashi; Arai, Yasuo

The electrochemical behavior of burnup-simulated uranium nitride fuels containing representative solid fission product elements, UN+Mo (Mo = 2.84wt%), UN+Pd (Pd = 4.6wt%) and (U,Nd)N (NdN = 8.0wt%), was investigated in the molten LiCl-KCl eutectic salt with 0.54wt% UCl in order to clarify the effect of fission products on the dissolution of actinide nitrides and behavior of FPs in the electrorefining process of spent nitride fuel. The electrochemical dissolution of UN began at about -0.75 V 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 V vs. Ag/AgCl, most of UN was dissolved into LiCl-KCl as UCl at the anode, and U was recovered in the liquid Cd cathode in all samples. Further, Nd was dissolved at the anode and accumulated into LiCl-KCl as NdCl, while Mo and Pd were not dissolved but remained at the anode.