Radiation measurements in the Chiba Metropolitan Area and radiological aspects of fallout from the Fukushima Dai-ichi Nuclear Power Plants accident

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• 作者：Hikaru Amano ; ^{h-amano@jcac.or.jp} ; Masakazu Akiyama ; Bi Chunlei ; Takao Kawamura ; Takeshi Kishimoto ; Tomotaka Kuroda ; Takahiko Muroi ; Tomoaki Odaira ; Yuji Ohta ; Kenji Takeda ; Yushu Watanabe ; Takao Morimoto
• 关键词：Fukushima Dai-ichi Nuclear Power Plants accident ; Anthropogenic radionuclides ; Fallout ; Tap water ; Dose estimation
• 刊名：Journal of Environmental Radioactivity
• 出版年：2012
• 期刊代码：45_0265931x
• 类别：env
• 出版时间：September, 2012
• 卷：111
• 期：Complete
• 页码：42-52
• 文件大小：907 K

摘要

Large amounts of radioactive substances were released into the environment from the Fukushima Dai-ichi Nuclear Power Plants in eastern Japan as a consequence of the great earthquake (M 9.0) and tsunami of 11 March 2011. Radioactive substances discharged into the atmosphere first reached the Chiba Metropolitan Area on 15 March. We collected daily samples of air, fallout deposition, and tap water starting directly after the incident and measured their radioactivity. During the first two months maximum daily concentrations of airborne radionuclides observed at the Japan Chemical Analysis Center in the Chiba Metropolitan Area were as follows: 4.7聽脳聽10¹聽Bq聽m^鈭? of ¹³¹I, 7.5聽Bq聽m^鈭? of ¹³⁷Cs, and 6.1聽Bq聽m^鈭?聽of ¹³⁴Cs. The ratio of gaseous iodine to total iodine ranged from 5.2聽脳聽10^鈭? to 7.1聽脳聽10^鈭?. Observed deposition rate聽maxima were as follows: 1.7聽脳聽10⁴聽Bq聽m^鈭?聽d^鈭? of ¹³¹I, 2.9聽脳聽10³聽Bq聽m^鈭?聽d^鈭? of ¹³⁷Cs, and 2.9聽脳聽10³聽Bq聽m^鈭?聽d^鈭? of ¹³⁴Cs. The deposition velocities (ratio of deposition rate to concentration) of cesium radionuclides and ¹³¹I were detectably different. Radioactivity in tap water caused by the accident was detected several days after detection of radioactivity in fallout in the area. Radiation doses were estimated from external radiation and internal radiation by inhalation and ingestion of tap water for people living outdoor in the Chiba Metropolitan Area following the Fukushima accident.