A method for the separation of U and RE from LiCl–KCl eutectic salt containing a high concentration of RE

In the pyroprocessing of used nuclear fuel, it is difficult to recover U in a recyclable form from LiCl–KCl eutectic salt containing a high concentration of rare earths (REs) by co-deposition of U and RE. To derive a solution to this problem, it is necessary to develop a technology to reduce the RE concentration or separate the RE in the salt. To this end, an integrated process of chemical conversion of UCl 3 into an oxide form and electro-deposition of NdCl 3 in a metal form was evaluated using a simulated LiCl–KCl salt containing about 1.4 wt% of UCl 3 and 4.0 wt% NdCl 3 in this study. Through the integrated process, higher than 99% conversion efficiency of U was obtained and the concentration of Nd in the simulated salt was reduced to less than 1/100. It is expected that the integrated process also can be applied effectively to the recovery of U from LiCl–KCl eutectic salt containing a high concentration of RE.