Inhibition of Cs137 contamination in cesium iodide

We have extensively studied the mechanism of the Cs137 and Cs134 contamination in CsI compounds. The nuclei Cs137 and Cs134 in various samples have been studied using a HPGe detector at deep underground. The main source of the Cs137 contamination in CsI powder was water dissolved Cs137 used in the chemical process of cesium extraction at company side. We also found that Cs134 was produced mainly from Cs133 by neutron capture. We have successfully produced CsI powder containing no more than 2 mBq/kg of Cs137 by using only ultra-pure water for whole extraction process from raw ore (pollucite).