XRD and EXAFS simulation study of molten uranium trichlorides

Okamoto, Yoshihiro  ; Shiwaku, Hideaki   ; Suzuki, Shinichi; Yaita, Tsuyoshi; Paul, M.*

We have investigated the local structure and structural change of trivalent uranium chloride (UCl) melts by high-temperature X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) techniques. A molecular dynamics (MD) simulation technique was essentially used in the data analysis of the XRD and the EXAFS. The XRD data of molten pure UCl was reproduced by the simulation with a polarizable ionic model. The potential model, which had been optimized by comparison with the XRD structural data, was also reproduce the transport properties like the diffusion coefficient, electrical conductivity and shear viscosity. The EXAFS analysis was performed to elucidate the mixing effect of molten UCl in molten alkali chlorides (LiCl-KCl). It can be estimated from the EXAFS and the MD results that a stable octahedral coordination structure like (UCl) is not formed in UCl-LiCl binary system.