Development of cesium-free mineralization for volume reduction and reuse of radioactive contaminated soil

Shimoyama, Iwao   ; Honda, Mitsunori   ; Kogure, Toshihiro*; Baba, Yuji  ; Hirao, Norie*; Okamoto, Yoshihiro  ; Yaita, Tsuyoshi; Suzuki, Shinichi

The decontamination method has not been established for soil contaminated with radioactive Cs. We adopted weathered biotite (WB) which sorbed non-radioactive Cs as a model contaminated soil and applied heating treatment to the WB at 700C under a low pressure condition with CaCl or KCl salt. X-ray fluorescence analysis showed that almost all Cs was removed after the heating at 700C with CaCl and Ca became dominant with temperature. X-ray diffraction and transmission electron microscopy analysis indicated some phase transition from WB after the heating treatment. These results suggest a model that Ca derived from the salt induced the formation of augite, and that Cs were eliminated from the product as these large-size cations cannot constitute augite. Based on this model, we propose Cs free mineralization which can achieve decontamination and reuse of soil in Fukushima.