Radiation monitoring and evaluation of exposure doses to lift the evacuation orders for the zones designated for reconstruction and recovery

Sanada, Yukihisa   ; Kurikami, Hiroshi  ; Funaki, Hironori ; Yoshimura, Kazuya  ; Abe, Tomohisa ; Ishida, Mutsushi*; Tanimori, Soichiro*; Sato, Rina

Japanese government starts to consider radiation protection in the "specific reconstruction reproduction base area" of which evacuation order will be lifted by 2023. It is essential to grab the present situations of radiation contamination and evaluate exposure dose in the area to realize the plan. Many surveys have evaluated the distributions of air dose rate and exposure dose has been estimated based on the results since the Fukushima Daiichi Nuclear Power Plant accident. Nevertheless, more detailed information on exposure is needed for the areas because its radiation level is relatively high. That is also to help make prudent evaluation plan. This study aimed to evaluate the detailed contamination situation there and estimate exposure dose with considering areal circumstances. Investigations were carried out for (1) airborne survey of air dose rate using an unmanned helicopter (2) evaluation of airborne radiocesium and (3) estimation of external/internal effective doses for typical activity patterns assumed.