Research and development behind a computation system for 3D distributions of air dose rates in the environment. Estimating environmental radiation doses using PHITS together with remote sensing data

Here we outline a system for generating three dimensional models of urban and rural areas in Fukushima Prefecture. The ¹³⁴Cs and ¹³⁷Cs radioactivity distribution can be set flexibly across the different components of the model. The models incorporate realistic representations of local buildings, individual conifer and broadleaf trees, and the topography of the land surface. The system is demonstrated by modelling a suburban area 4 km from the Fukushima Daiichi Nuclear Power Plant that has yet to be decontaminated. Air dose rates calculated in PHITS were correlated with measurements taken across the site in a car-borne survey. (author)