A Preliminary dose assessment for the population in an area outside the 30 km zone after the Fukushima Daiichi Nuclear Power Plant accident

Kimura, Masanori ; Kinase, Sakae   ; Takahara, Shogo  ; Homma, Toshimitsu

The dose received by the public was assessed for one month since the Fukushima Daiichi Nuclear Power Plant accident onset to reconstruct and predict external and internal doses to the public at an area using the radiation monitoring data provided by regulatory authorities. The cumulative doses were estimated by fitting the exponential model, with the decay of nuclides (I, Cs + Cs) considered, to the measurement data. The external doses were evaluated by supplementing the measurement data with the estimates. In addition, the internal doses by inhalation and ingestion of radioiodine I were evaluated using the concentration of airborne effluents and the tap water. Consequently, the total dose for the public was found to be less than 20 mSv. The averted dose by restrictions on the ingestion of the tap water was also discussed.