Mathematical modeling of radio-cesium migrations and air dose rate changes in eastern Fukushima Prefecture

Kitamura, Akihiro   ; Kurikami, Hiroshi  ; Sakuma, Kazuyuki   ; Malins, A.  ; Okumura, Masahiko   ; Itakura, Mitsuhiro  ; Yamada, Susumu  ; Machida, Masahiko  

Radioactive cesium that was deposited over Fukushima after the accident at the FDNPP is one of the major concerns regarding health physics. In order to predict the future distribution of radioactive cesium and resulting air dose rate at any location in Fukushima, we have integrated a number of mathematical models covering different time and scales. We present simulation results of sediment movement and radioactive cesium migration using semi empirical and physics based watershed models, and that of sediment and radioactive cesium behavior in a dam reservoir using one and two dimensional river simulation models. We also present a tool for calculating air dose rates from arbitrary radio cesium depth profiles and spatial distributions. The predicted dose rates were compared against dose rates measured in the field with handheld survey meters and good correlation was found between the two.