Recovery of uranium and plutonium from pyrochemical salt matrix using supercritical fluid extraction

Pyrochemical reprocessing of spent nuclear fuel involves use of molten salts for the separation of actinides from fission products. Salt waste arising from this process contains residual actinides along with fission products. In the present study, extraction of residual uranium and plutonium from pyrochemical salt matrices was investigated using supercritical fluid extraction (SFE) technique. Supercritical carbon dioxide (SCCO2) containing various ligands was examined to recover actinides from salt matrix with minimum generation of secondary liquid waste. Influence of ligand, salt matrix, temperature, pressure, co-solvent and HNO3 concentration was examined for efficient recovery of actinides. Among the ligands employed in present study, SCCO2 containing trioctylmethylammonium chloride resulted in better recovery of actinides. The recovery of uranium from salt matrix was also demonstrated using semi-preparative scale SFE facility. This study is first of its kind for recovery of actinides from pyrochemical salts using SFE.