Graduate School of Health Sciences, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan.
Institute of Radiation Emergency Medicine, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori 036-8564, Japan.
Int J Environ Res Public Health. 2021 Jan 22;18(3):978. doi: 10.3390/ijerph18030978.
Ten years have elapsed since the accident at the Fukushima Daiichi Nuclear Power Plant in 2011, and the relative contribution of natural radiation is increasing in Fukushima Prefecture due to the reduced dose of artificial radiation. In order to accurately determine the effective dose of exposure to artificial radiation, it is necessary to evaluate the effective dose of natural as well as artificial components. In this study, we measured the gamma-ray pulse-height distribution over the accessible area of Namie Town, Fukushima Prefecture, and evaluated the annual effective dose of external exposure by distinguishing between natural and artificial radionuclides. The estimated median (range) of absorbed dose rates in air from artificial radionuclides as of 1 April 2020, is 133 (67-511) nGy h in the evacuation order cancellation zone, and 1306 (892-2081) nGy h in the difficult-to-return zone. The median annual effective doses of external exposures from natural and artificial radionuclides were found to be 0.19 and 0.40 mSv in the evacuation order cancellation zone, and 0.25 and 3.9 mSv in the difficult-to-return zone. The latest annual effective dose of external exposure discriminated into natural and artificial radionuclides is expected to be utilized for radiation risk communication.
自 2011 年福岛第一核电站事故发生以来，已经过去了十年，由于人工辐射剂量的减少，福岛县的自然辐射相对贡献正在增加。为了准确确定人工辐射照射的有效剂量，有必要评估自然和人工成分的有效剂量。在这项研究中，我们测量了福岛县女川町可及区域的伽马射线脉冲高度分布，并通过区分天然和人工放射性核素来评估外照射的年有效剂量。截至 2020 年 4 月 1 日，在取消撤离命令区，人工放射性核素导致的空气吸收剂量率的中位数（范围）为 133（67-511）nGy h，在难以返回区为 1306（892-2081）nGy h。在取消撤离命令区，天然和人工放射性核素导致的外照射年有效剂量中位数分别为 0.19 和 0.40 mSv，在难以返回区分别为 0.25 和 3.9 mSv。预计将利用最新区分天然和人工放射性核素的外照射年有效剂量进行辐射风险沟通。
