ELUTION OF RADIOCESIUM FROM SOIL AND SLUDGE

Elution of radiocesium from soil was studied as a first step for the reduction of external radiation exposure. Three experiments were independently carried out on elution of 137Cs with: (I) rainfall, (II) oxidation power of ozone, and (III) chemical reagents. In experiment I, rainfall was simulated by passing deionized water through a soil column, but no elution of 137Cs was observed. A sludge sample which was contaminated with the fallout from the Fukushima Daiichi Nuclear Power Plant accident was treated with ozone micro-bubbles and ozone gas in experiment II, but 137Cs was not released from the sludge. The oxidation power of ozone had no effects on the elution of 137Cs under the present experimental conditions. In experiment III, Good\u27s buffers such as MES (pH6.0) and HEPES (pH 7.5) were used to elute 137Cs from soil; however, 137Cs eluted into these buffers was below the detection limit. When the soil was soaked with 100 mM KCl and 100 mM (NH4)2SO4, 4.1% and 15.4% respectively, of the total 137Cs radioactivity were eluted into these chemical solutions. From these results, it was concluded that 100 mM (NH4)2SO4 was the most effective chemical to elute 137Cs from the soil.Environmental monitoring and dose estimation of residents after accident of TEPCO\u27s Fukushima Daiichi Nuclear Power Station