Evaluation of Environmental Contamination and Estimated Radiation Exposure Dose Rates among Residents Immediately after Returning Home to Tomioka Town, Fukushima Prefecture
Evaluation of Environmental Contamination and Estimated Radiation Exposure Dose Rates among Residents Immediately after Returning Home to Tomioka Town, Fukushima Prefecture
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DOI：
10.3390/ijerph16091481
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发表时间：
2019-05-01
影响因子：
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通讯作者：
Takamura, Noboru
中科院分区：
文献类型：
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作者：
Matsuo, Masahiko;Taira, Yasuyuki;Takamura, Noboru
2017年4月1日，距离福岛第一核电站（FDNPS）事故已经过去了6年，日本政府宣布居住在福岛县富冈町的部分居民可以返回家园。在富冈富冈町的居民返回家园后，立即对居民的生活区（住宅等生活空间），包括以FDNPS为中心的10 km范围内的限制区域内的环境污染和人工放射性核素的照射剂量率进行了评价。在疏散命令已经解除的地区，空气剂量率的中位数为室内0.20 mu Sv/h，室外0.26 mu Sv/h，辐射照射剂量率为1.6 mSv/y。相比之下，在“难以返回区”，空气剂量率的中位数为2.3 μ Sv/h（20 mSv/y）的室外。此外，在疏散令解除地区，表层土壤中形成剂量的人工放射性核素（放射性铯）为0.018 μ Sv/h（0.17 mSv/y），在难以返回地区为0.73 μ Sv/h（6.4 mSv/y）。这些研究结果表明，在富冈镇解除疏散令的地区，土壤样品中人工放射性核素的当前浓度一直在下降;然而，在难以返回的地区仍然存在重大的外部照射风险。富冈镇的情况预计将是第一个重建模式，包括难以返回的地区。
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 mu Sv/h indoors and 0.26 mu Sv/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 mu Sv/h (20 mSv/y) outdoors. Moreover, the dose-forming artificial radionuclides (radiocesium) in the surface soil were 0.018 mu Sv/h (0.17 mSv/y) in the evacuation order-lifted areas and 0.73 mu Sv/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.