Effects of non-decontamination human activities on the reduction of ambient dose equivalent rates in residential areas near the Fukushima Daiichi Nuclear Power Plant

Kim, M.  ; Yoshimura, Kazuya  ; Sakuma, Kazuyuki   ; Malins, A.*; Abe, Tomohisa ; Nakama, Shigeo ; Machida, Masahiko  ; Saito, Kimiaki  

This study quantitatively evaluated the effects of non-decontamination human activities, such as traffic, on ambient dose rates in residential areas near the Fukushima Daiichi Nuclear Power Plant through field measurements and simulations. Field surveys showed that areas with higher traffic had greater reductions in Cs deposition, suggesting that vehicular movement may enhance cesium weathering. Monte Carlo simulations using 3D-ADRES confirmed that human activities accelerate the decrease in ambient dose rates on paved surfaces, with reductions of up to approximately 50%. These results indicate that non-decontamination human activities significantly contribute to lowering ambient dose rates.