To contribute to the reconstruction and revitalization of Fukushima Prefecture following the 2011 nuclear power disaster, annual individual doses were estimated for evacuees who will return home to Tamura City, Kawauchi Village, and Iitate Village in Fukushima. Ambient external dose rates and individual doses obtained with personal dosimeters were measured at many residential and occupational sites throughout the study areas to obtain fundamental data needed for the estimation. The measurement results indicated that the ratio of individual dose based on a personal dosimeter to the ambient external dose measurement was 0.7 with 10% uncertainty. Multiplying the ambient external dose by 0.7 may be an appropriate measure of the effective dose to an individual in the investigated area. Annual individual doses were estimated for representative lifestyles and occupations based on the ambient external dose rates at the measurement sites, taking into account the relationship between the ambient external dose and individual dose. The results were as follows: 0.6–2.3 mSv y−1 in Tamura, 1.1–5.5 mSv y−1 in Kawauchi, and 3.8–17 mSv y−1 in Iitate. For all areas investigated, the estimated dose to outdoor workers was higher than that to indoor workers. Identifying ways to reduce the amount of time that an outdoor worker spends outdoors would provide an effective measure to reduce dose.
*National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-City, Chiba 263-8555, Japan; †Department of Applied Physics, National Defense Academy of Japan, 1-10-20 Hashirimizu, Yokosuka-City, Kanagawa 239-8686, Japan; ‡Department of Radiation Physics and Chemistry, School of Medicine, Fukushima Medical University, 1 Hikarigaoka, Fukushima-City, Fukushima 960-1295, Japan; §Department of Human Care, Tohto College of Health Sciences, 4-2-11 Kamishiba-cho Nishi, Fukaya-City, Saitama 366-0052, Japan.
The authors declare no conflicts of interest.
Corresponding author: Kazuaki Yajima, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-City, Chiba 263-8555, Japan, or email at firstname.lastname@example.org.
(Manuscript accepted 25 March 2015)