Ecological half-life of radioactive caesium within 80 km-radius of the Fukushima Daiichi Nuclear Power Plant

福島第一原子力発電所80km圏内の放射性セシウムの環境半減期

木名瀬 栄   ; 佐藤 仁士; 高橋 知之*; 坂本 隆一*; 斎藤 公明  

Kinase, Sakae; Sato, Satoshi; Takahashi, Tomoyuki*; Sakamoto, Ryuichi*; Saito, Kimiaki

To obtain the perspective of assessing the evolution of the long-term exposure situation, prediction models have been developed for the radioactive caesium distribution within 80 km-radius of the Fukushima Daiichi Nuclear Power Plant. Exponential functions characterised by ecological half-lives of radioactive caesium were adapted for the preliminary prediction models. The ecological half-lives were evaluated using the changes in ambient dose equivalent rates. Cumulative distribution functions for the ecological half-lives of radioactive caesium were obtained for each land use. It was found that ecological half-life of radioactive caesium for forest areas is much larger than that for urban and water areas.