プラズマを用いた超高感度元素分析 4.誘導結合プラズマ質量分析法の環境放射能研究への応用

抄録

Applications of inductively coupled plasma mass spectrometry (ICP-MS) to the determination of long-lived radionuclides in environmental samples were summarized. In order to predict the long-term behavior of the radionuclides, related stable elements were also determined. Compared with radioactivity measurements, the ICP-MS method has advantages in terms of its simple analytical procedures, prompt measurement time, and capability of determining the isotope ratio such as²⁴⁰Pu/²³⁹Pu, which can not be separated by radiation. Concentration of U and Th in Japanese surface soils were determined in order to determine the background level of the natural radionuclides. The ²³⁵U/²³⁸U ratio was successfully used to detect the release of enriched U from reconversion facilities to the environment and to understand the source term. The ²⁴⁰Pu/²³⁹Pu ratios in environmental samples varied widely depending on the Pu sources. Applications of ICP-MS to the measurement of I and Tc isotopes were also described. The ratio between radiocesium and stable Cs is useful for judging the equilibrium of deposited radiocesium in a forest ecosystem.