In order to enhance the efficiency of pyrochemical technology, especially electrorefining process, physicochemical data of
trivalent uranium in LiCl–KCl eutectic at 773 K were measured, including molar absorptivity, formal potential and diffusion
coefficient of U3+ ions. The molar absorptivities of U3+ were determined to be 765 ± 48 and 686 ± 39 M−1 cm−1 at 465 and 550 nm, respectively. The formal potential of U3+/U4+ redox couple and diffusion coefficient of U3+ ions were measured to be −0.308 V vs. Ag/Ag+ and 8.7 × 10−6 M−1 cm−1, respectively. To elucidate the chemical behavior of U3+ ions under the existence of oxide ions, U3+ ions were reacted with oxides ions in situ produced at the LiCl–KCl media. Surprisingly, it was revealed from XRD patterns
that UO2 was formed from the reaction between U3+ ions and O2− ions with the molar ratio of 1:1.