Identification of penetration path and deposition distribution of radionuclides in houses by experiments and numerical model

実験と数値モデルによる家屋内の放射性物質の浸入経路と沈着分布の調査

廣内 淳 ; 高原 省五  ; 飯島 正史; 渡邊 正敏; 宗像 雅広 

Hirouchi, Jun; Takahara, Shogo; Iijima, Masashi; Watanabe, Masatoshi; Munakata, Masahiro

The dose assessment for people living in preparation zones for the lifting of the evacuation order is needed with the return of the residents. However, it is difficult to assess exactly indoor external dose rate because the indoor distribution and infiltration pathways of radionuclides are unclear. This paper describes indoor and outdoor dose rates measured in eight houses in the difficult-to-return zone in Fukushima prefecture to examine the distribution of radionuclides in a house and the main infiltration pathway of radionuclides. In addition, it describes also dose rates calculated with a Monte Carlo photon transport code to understand thoroughly the measurements. These measurements and calculations provide that radionuclides can infiltrate mainly through ventilations, windows, and doors, and then deposit near the gaps, while those infiltrate hardly through sockets and air conditioning outlets.