Analysis of influence of slopes nearby buildings on indoor radiation dose rates using PHITS

Furuta, Takuya   ; Takahashi, Fumiaki  

After the accident at the Fukushima Daiichi Nuclear Power Station, it became important to assess radiation doses accounting dose reduction by buildings in order to take measures for radiation protection reflecting life-styles of residents according to data of the radiation monitoring in open air. We have been analyzed the radiation dose reduction in buildings standing on a flat ground. However, slopes nearby buildings can be found in many situations of houses in Fukushima area. We performed simulation using PHITS and analyzed radiation dose rates in a wooden house, which is the most popular residential house in Fukushima area, standing nearby a slope. Here, radiation dose rates in the house were computed in a situation where radioactive cesium was distributed homogenously over the ground including the slope and compared with those in the house standing on a flat ground. We found that the variation of the dose rates in the house was not significant with and without the slope. Accordingly, high dose rates possibly found in a house nearby slopes are more likely, for instance, because of contaminated plants at the slopes than due to the geometrical effect of the slopes.