Assessment of Exposure Doses and Decontamination
（2017）
ＱIs there any way to efficiently remove radioactive Cs from contaminated soil?
ＡTo clay minerals, we added mixed salts （NaCl-CaCl2） as a high-performance absorbent of radioactive Cs to accelerate their reaction. Then, we heated them at relatively low temperatures and washed them with water to find that the radioactive Cs had been successfully removed.。
Fig.1 Cs K edge XAFS spectra using synchrotron X-rays heated from room temperature
(a) without mixed salts: no differences were observed between the shapes during processing from room temperature to 700 ℃ and back to room temperature.
(b) with mixed salts: the shapes of spectra were different before and after heating. These results indicate that the local Cs structure was drastically changed by heating in the presence of mixed salts.
Fig.2 Mechanism of Cs removal from weathered biotite
Synchrotron X-rays can determine the local Cs structure. These graphs show that during the course of molten salt cooling in the heat treatment with mixed salts, Cs first bonded to O and then to Cl instead of O.
Fig.3 Cs remaining in clay minerals after heat treatment with mixed salts
We confirmed that Cs was released with high efficiency after heating at 700 ℃.