Abstract

On 1 April 2017, six years have passed since the Fukushima Daiichi Nuclear Power Station (FDNPS) accident, and the Japanese government declared that some residents who lived in Tomioka Town, Fukushima Prefecture could return to their homes. We evaluated environmental contamination and radiation exposure dose rates due to artificial radionuclides in the livelihood zone of residents (living space such as housing sites), including a restricted area located within a 10-km radius from the FDNPS, immediately after residents had returned home in Tomioka town. In areas where the evacuation orders had been lifted, the median air dose rates were 0.20 μSv/h indoors and 0.26 μSv/h outdoors, and the radiation exposure dose rate was 1.6 mSv/y. By contrast, in the “difficult-to-return zone,” the median air dose rate was 2.3 μSv/h (20 mSv/y) outdoors. Moreover, the dose-forming artificial radionuclides (radiocesium) in the surface soil were 0.018 μSv/h (0.17 mSv/y) in the evacuation order-lifted areas and 0.73 μSv/h (6.4 mSv/y) in the difficult-to-return zone. These findings indicate that current concentrations of artificial radionuclides in soil samples have been decreasing in the evacuation order-lifted areas of Tomioka town; however, a significant external exposure risk still exists in the difficult-to-return zone. The case of Tomioka town is expected to be the first reconstruction model including the difficult-to-return zone.

Highlights

  • More than eight years have passed since 11 March 2011, the date of the 9.0-magnitude GreatEast Japan Earthquake, subsequent tsunami, and disaster at the Fukushima Daiichi Nuclear PowerStation (FDNPS), which is operated by the Tokyo Electric Power Company

  • Absorption of 137 Cs appears to be the primary process regulating the 137 Cs distribution in the soil profiles over five years of monitoring after contamination [34]. These findings suggest that environmental contamination and the effective dose rates on the ground in the evacuation order-lifted areas will be decreased by decontamination procedures, such as the removal of surface soil [35] (Figure 3)

  • We evaluated environmental contamination and contributions from the external exposure due to radiocesium in Tomioka town near the Fukushima Daiichi Nuclear Power Station (FDNPS)

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Summary

Introduction

More than eight years have passed since 11 March 2011, the date of the 9.0-magnitude GreatEast Japan Earthquake, subsequent tsunami, and disaster at the Fukushima Daiichi Nuclear PowerStation (FDNPS), which is operated by the Tokyo Electric Power Company. More than eight years have passed since 11 March 2011, the date of the 9.0-magnitude Great. East Japan Earthquake, subsequent tsunami, and disaster at the Fukushima Daiichi Nuclear Power. Station (FDNPS), which is operated by the Tokyo Electric Power Company. Various radionuclides were released from the FDNPS into the atmosphere, eventually being deposited on land and at sea in the surrounding areas [1]. The estimated total amount of iodine-131 (131 I) released ranged from about 100–500 petabecquerel (PBq), and that of cesium-137 (137 Cs) was generally in the range of. Res. Public Health 2019, 16, 1481; doi:10.3390/ijerph16091481 www.mdpi.com/journal/ijerph

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