Uranium chemical species in LiCl-KCl eutectic under different conditions for the dissolution of U3O8

As a typical uranium oxide , the electrochemical behaviors of U 3 O 8 in molten salt have attracted many research endeavors, but its dissolution behavior and related mechanism in molten salt has been less well understood. In this work, we reported the dissolution of U 3 O 8 in LiCl-KCl eutectic with the assistance of NH 4 Cl, which has potential significance for the pyrochemical reprocessing of spent oxide fuels. The spectroscopic techniques such as fluorescence emission spectroscopy, UV-Vis absorption spectroscopy , and X-ray Absorption Fine Structure (XAFS) were used to determine the chemical species during the dissolution process of U 3 O 8 . The results show that U 3 O 8 can be completely dissolved in molten salt under the air atmosphere, and it exists in the form of [UO 2 Cl 4 ] 2− . In contrast, under an argon atmosphere , the soluble [UO 2 Cl 4 ] 3− and insoluble UO 2 were detected as the main products.