URANIUM,THORIUM AND RARE EARTH ELEMENTS DISTRIBUTION IN FUKUSHIMA SOIL SAMPLES

There is a growing interest on parent daughter pairs in uranium (U) and thorium (Th) decay series, which are present in natural materials but not in radioactive equilibrium. Rare earth elements (REEs) are important geochemical tracers, which appear as natural trace metals in whole geosphere and as radionuclides in the decay series of nuclear fission. Therefore, measurement of REEs with U and Th in soil samples is highly important. We have used a microwave acid-digestion system for fast decomposition of soil into solution. It is necessary to get more data on REEs, U and Th in Fukushima soils after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. Different types of chemical digestion methods were carried out for validation of analytical procedure and accuracy with certified reference materials (CRMs) supplied by Geological Survey ofJapan e.g. JLk-1, JSd-2 and JB-3. Inductively coupled plasma mass spectrometry (ICP-MS)technique was used for precise, accurate and rapid determination of REEs, U and Th simultaneously from digested soil samples. The developed method was applied to Fukushima soil samples. Major elements (as an oxide) were analyzed by X-ray Fluorescence Spectrometry to understand nature of mineral composition of soils. Abundance ratio of Th/U varies from (2.5-4), whereas total REEs (excluding Y) concentration range between 10-100 μg/g.9th International Conference on High Level Environmental Radiation Areas-For Understanding Chronic Low-Dose-Rate Radiation Exposure Health Effects and Social Impacts (ICHLERA 2018