Dose rate survey inside and outside three public buildings located approximately 40 km northwest of the Fukushima Daiichi Nuclear Power Stations

We surveyed the reduction of the dose rate inside three public buildings compared to the dose rate outside in Kawamata-machi, Fukushima Prefecture. The three buildings—a wooden construction district meeting place, a steel construction public hall, and a reinforced concrete school building—are located approximately 40 km northwest of TEPCO's Fukushima Daiichi Nuclear Power Stations. The dose rate measurement, performed with a NaI(Tl) scintillation survey meter, was carried out on January 19, 2012. We evaluated the reduction of the dose rate inside the building using the reduction factor, which was determined to be the ratio of the dose rate inside the building to that outside the building. The reduction factors 1 m inside from the window were 0.51-0.56 for the wooden building, 0.34-0.51 for the steel construction building, and 0.27-0.31 for the concrete building. The reduction factors at the center of the room were 0.48 for the wooden building, 0.23-0.34 for the steel construction building, and 0.10-0.16 for the concrete building. (author)