[1I13-17] Environmental Dynamics 3

[1I13] Investigation on distribution of radioactive substances in Fukushima

(13) Evaluation of indoor dose reduction factor based on air dose rate measurement

*Rina Sato¹, Kazuya Yoshimura¹, Yukihisa Sanada¹, Tetsuro Sato², Tsubasa Mori², Marie Takagi² (1. JAEA, 2. Hitachi Solutions East Japan)

Keywords:Fukushima Daiichi Nuclear Power Station accident, ambient dose equivalent, reduction factor, natural radionuclide

In order to accurately estimate air dose rates of indoors with a high percentage of stay, indoor dose reduction factor was evaluated based on indoor and outdoor air dose rate measurements, taking into account air dose rates due to natural radionuclides. The measurements were conducted on wooden and concrete buildings in 2021 in municipalities with specified reconstruction and revitalization base. Indoor air dose rates were estimated from outdoor air dose rates using representative values of the evaluated indoor dose reduction factors. As a result, indoor air dose rates were estimated more accurately when the effect of natural radionuclides was taken into account, because the error indicators were smaller than those in the case without the effect of natural radionuclides.