XAFS analysis of each element in simulated high level liquid wastes

Okamoto, Yoshihiro  ; Nagai, Takayuki  ; Kobayashi, Hidekazu ; Shiwaku, Hideaki   ; Sato, Nobuaki*

X-ray absorption fine structure (XAFS) analyses were performed to elucidate for simulated high level liquid waste (HLLW) and its powder samples obtained by heating up to 800C. The purpose of this work is to elucidate chemical state of each element in the samples when the HLLW components mix with borosilicate glass. In the present work, a simulated HLLW equivalent to the HLLW stored in the JAEA Tokai Vitrification Facility (TVF) was used to evaluate the chemical state of Cr, Mn, Fe, Zr, Mo, Ru, Rh, Pd and Ce elements. As the results of XAFS data analysis of cerium L-edge, it was revealed that oxidation state of cerium in the simulated HLLW was trivalent but changed to tetravalent (chemical form is CeO) at 400C. The molybdate ion (MoO), which is generally observed in the waste glass form, was found in the powder sample after heating to 500C. In addition to heating temperature from 100C to 800C, influence of atmosphere at the heating (in air and in argon) was evaluated in the present work.