Study of Molten Salt Electrorefining ofU-Pu-Zr Alloy Fuel

Electrorefining of unirradiated metal alloy fuel, U-20Pu-10Zr (% by weight), was carried out in an Ar atmosphere cell to obtain a basic knowledge of spent fuel treatment. Before electrorefining, the Pu ion concentration in LiCl-KCl electrolyte was adjusted to 4 wt.% using pure Pu metal and CdCl2. Cylindrical alloy fuel was anodically dissolved in the salt electrolyte. Electrotransport to either liquid Cd cathode or solid cathode was carried out several times in galvanic mode. The deposit on the solid cathode mostly consisted of metal U and entrained salt and took place at high current efficiency. The recovery of Pu and Am into a liquid cadmium cathode was also demonstrated with high current efficiency. The anodic dissolution of the fuel alloy was found to progress from the outside whilst leaving a dense salt layer on the alloy surface. The peculiar fluctuation of anode potential during U-Pu-Zr dissolution was explained by the competitive oxidation of U-Pu and Zr.