Indoor and outdoor radionuclide distribution in houses after the Fukushima Dai-ichi Nuclear Power Plant accident

Hirouchi, Jun ; Takahara, Shogo  ; Yoshimura, Kazuya  

Information on the radioactivity distribution inside and outside houses is useful for indoor external dose assessments. In this study, we collected both soil samples around the target houses and house material samples (i.e., of the floor, inner wall, ceiling, outer wall, and roof). The radioactivity of the samples was measured using a high-purity germanium detector. The surface contamination densities of the floor, inner wall, ceiling, outer wall, and roof relative to the ground were 3 107 10, 6 104 10, 7 103 10, 2 101 10, and 4 102 10, respectively. The relative surface contamination densities varied depending on the material, its location, and the orientation of the surface.