| Summary: | Pyroprocessing is a critical technology for recycling spent nuclear fuel, which enhances the sustainability of nuclear power generation. This process begins with metal oxides, which must be converted into metal chlorides to facilitate further processing, including electrorefining and electrowinning. In this work, we investigate the chlorination of lanthanide (Nd, Gd) and actinide (Th, Np) oxides in LiCl-KCl molten salt and confirm the chlorination through electrochemical and spectroscopic analyses. Nd2O3 and Gd2O3 are chlorinated using NH4Cl, with electrochemical measurements demonstrating the electrodeposition and dissolution currents of Nd3+ and Gd3+ ions. Th and Np chlorides are prepared using AlCl3 as a reactant. The reaction between ThO2 and AlCl3 produces ThCl4, as evidenced by the electrodeposition-dissolution currents of Th4+. For the chlorination of NpO2, NpO2Cl is first prepared by dissolving NpO2 in acidic solutions and then drying. Subsequently, the reaction of NpO2Cl and AlCl3 in molten LiCl-KCl yields NpCl4. Electrochemical and UV–Vis spectroscopic measurements confirm the redox reactions of Np4+/Np3+/Np0 and the presence of NpCl4 in the molten LiCl–KCl, respectively.
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