A Simple method for selective quantification of cesium-134 and 137 using NaI(Tl) spectrometer

Yin, Y.-G.; Suzui, Nobuo; Yamaguchi, Mitsutaka; Kawachi, Naoki; Tanoi, Keitaro*; Nakanishi, Tomoko*; Chino, Mitsuo*; Nakamura, Shinichi*; Fujimaki, Shu

There is very high demand for analysis of radiocesium content in contaminated samples such as soils and foods. NaI(Tl) scintillation spectrometer can be a most promising tool for this situation because it has advantages compared to Ge semiconductor detector, that is, lower price, small size and light weight, and easy handling. However, NaI(Tl) scintillation spectrometer has a critical disadvantage that it cannot completely distinguish the rays emitted by Cs-134 and Cs-137 and thus has difficulty to measure Cs-134 and Cs-137 selectively. In this study, we propose a simple method to determine the amounts of Cs-134 and Cs-137 separately without any special software, based on the spectral data obtained with NaI(Tl) scintillation spectrometer. Several samples from contaminated fields were subjected to this method and the results successfully showed high consistency (87% - 106%) with the values obtained with Ge semiconductor detector, for the respective nuclides.