A Study on prediction models for caesium distribution within the 80 km radius of the Fukushima Daiichi Nuclear Power Plant

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

In the present study, preliminary prediction models for caesium distribution within 80 km radius of the Fukushima Daiichi Nuclear Power Plant were developed using the radiological quality of the environment. Bi-exponential functions characterised by fast and slow ecological half-life components were adopted for the prediction models. Ecological half-life components were evaluated using the changes in ambient dose equivalent rates. Cumulative distribution functions for the ecological half-life of caesium were obtained for each land use. It was found that ecological half-life of caesium for forest areas was much larger than that for urban and rice-paddy areas. The preliminary conclusion was that the prediction models for caesium distribution specific to land use should be sophisticated.