Study on the electrolytic reduction of kilogram-scale U3O8 in molten LiCl

This study investigated the electrolytic reduction of kilogram-scale U₃O₈ pellets in molten LiCl and focused on optimizing the process for nuclear fuel cycle applications. Critical developments included resolving carbon impurity issues in LiCl, implementing a sequential kerosene-cyclohexane washing process at 150 °C for lithium anode pretreatment, and establishing optimal pellet fabrication parameters. By adjusting the sintering atmosphere, the pellet density (4.5–8.5 g/cm 3 ) and chemical composition (U₃O₈ or U₄O₉) could be controlled. The electrolytic reduction used a stainless-steel cathode basket loaded with sintered pellets and a lithium metal counter electrode. The experiment was conducted in an inert-atmosphere glove box for 181h. The results showed reduction extents of 99.09% for U₃O₈ and 99.17% for U₄O₉, a uranium metal production rate of 55.7 gU/h, and a current efficiency of 56.1%. X-ray diffraction analysis confirmed that the primary reduction products were metallic uranium and uranium carbide.