- 著者
- Naoko Morita Miwa Miura Toshiro Usa Takashi Kudo Naoki Matsuda
- 出版者
- 日本放射線安全管理学会
- 雑誌
- Radiation Safety Management (ISSN:13471511)
- 巻号頁・発行日
- vol.12, no.2, pp.48-55, 2013 (Released:2013-12-19)
- 参考文献数
- 20
The internal doses of 372 persons who were dispatched to the Fukushima prefecture at any time from April 2011 to March 2012 were examined using a whole body counter within 2 months after they left Fukushima. 131I was only detected in April while 134Cs and 137Cs were found up to November 2011. The maximum committed effective dose and thyroid equivalent dose were 22.4 μSv and 0.4 mSv, respectively, which were observed in April 2011 by the scenario of acute inhalation. The internal radioactivity was found in persons staying in almost all of the interior and the coastal regions regardless of the distance from the Fukushima-Daiichi nuclear power plant. Although there was no statistical significance, the detection rate of 134Cs and 137Cs appeared higher in subjects dispatched for relatively long-terms. Comparison of internal doses evaluated by the whole body counter and by prediction from environmental radioactivity indicates that the intake of radioactivity in March, April and possibly May 2011, would be mainly attributable to the inhalation of airborne radioactive particles, whereas in June and later months ingestion of contaminated food would be the major route of radioactive intake. These results suggest that the risk for internal exposure existed for approximately six months after the radiological accident in almost the entire area of Fukushima, however, adverse health consequences by the radiation dose due to internal exposure seem to be negligible. Furthermore, the present risk for internal exposure is quite low in the normal living situation.
- 著者
- Takahira TAKEMOTO Kazutaka OHSAWA Naoki MATSUDA
- 出版者
- Japanese Society of Radiation Safety Management
- 雑誌
- Radiation Safety Management (ISSN:13471511)
- 巻号頁・発行日
- vol.19, pp.49-57, 2020 (Released:2020-06-26)
- 参考文献数
- 24
To support the safe return of residents after the TEPCO Fukushima Daiichi Nuclear Power Plant accident, cleaning methods and materials for the removal of radiocesium (137Cs) from household surfaces were compared. A spot contaminated with 137Cs on a vinyl floor sheet or a glass plate was wiped in different moisture conditions with different cleaning materials, including a paper sheet, cellulose sponge, polyester sheet, and a polyesterpolyamide sheet. Radioactive solid particles on a vinyl sheet were wiped with miniature mops made of cellulose sponge, polyester microfiber, or cotton yarn. There was little difference in the removal of radioactivity among cleaning materials when the contaminated spot was wiped in wet conditions. The removal of contaminated particles depended on the structure of the mop. The use of an abrasive and a detergent worked well for the vinyl sheet and the glass plate, respectively. These observations suggested that, in appropriate conditions, effective decontamination was achievable by regular indoor cleaning with commercially available cleaning devices.