著者

藤原 慶子 高橋 知之 高橋 千太郎

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.51, no.1, pp.19-26, 2016 (Released:2016-07-06)

参考文献数

11

被引用文献数

4

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The accident at the Fukushima nuclear power plant in 2011 caused the release of large amounts of tellurium (Te) isotopes, with radio-cesium (Cs) and radio-iodine (I), into the environment. The total amounts of 127mTe and 129mTe released from the nuclear power plant were estimated as 1.1 × 1015 and 3.3 × 1015 Bq, respectively. At the location where the deposition of 129mTe was relatively large, the ratio of the radioactivity of 129mTe to that of 137Cs reportedly reached 1.49 on June 14, 2011. Since 127mTe has a relatively long half-life, it possibly contributed to the internal radiation dose at the early stage after the accident. In this paper, the ratio of the committed effective dose of 127mTe to that of 137Cs after the oral ingestion of rice was estimated by using various reported parameters. The relevant parameters are: 1) the deposition ratios of 127mTe, 129mTe, and 134Cs to 137Cs; 2) the deposition ratio of 127mTe to 129mTe; 3) the transfer factors of Te and Cs; and 4) the effective dose coefficients for 127mTe, 129mTe, 134Cs, and 137Cs. The ratios of the committed effective dose of 127mTe to that of 137Cs were calculated for adults after a single ingestion at the time of the rice harvest. The ratio was 0.45 where the 129mTe/137Cs in the soil was higher and 0.05 where the level of 129mTe/137Cs was average. The ratio of the committed effective dose from 129mTe and 127mTe to that from 137Cs for one year reached 0.55 and 9.03 at the location where the level of 129mTe/137Cs in the soil was higher. These data could indicate that radioactive Te should not be disregarded in reconstructing the internal radiation dose from food for one year after the accident.

著者

藤原 慶子 山崎 敬三 高橋 知之 高橋 千太郎 北川 晃三 神藤 克人

出版者

日本保健物理学会

雑誌

保健物理 (ISSN:03676110)

巻号頁・発行日

vol.47, no.4, pp.282-285, 2012 (Released:2013-12-17)

参考文献数

8

被引用文献数

1

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After the Fukushima Daiichi Nuclear Power Plant Accident, many people are concerned about the contamination of radioactive substances in their ordinary surrounding environment. In this study, we determined the levels of radioactive contamination with 137Cs in towels, very common textile products in our life, after exposing those to the soil collected from a farm field near Fukushima city. Three kinds of towels made from the same cotton fiber with different thickness were exposed to the soil under dry or water-suspension conditions. The radioactivities of 137Cs retained/absorbed were 30-50% of the loaded radioactivity per gram weight of the towel. When their weight and absorbency are taken into consideration, the differences in thickness did not so much affect the above values. Under standard washing condition, which mimic those with household washing machine, almost all the radioactive cesium were removed from the towels contaminated under the dry conditions, whereas only 50-70% were removed when the towels were contaminated under the wet conditions. A commercial soil-release treatment (Preshade-SR) didn't reduce the contamination under both dry and wet conditions, although processing the towels with silver nano-particles did.

著者

藤原 慶子

出版者

Kyoto University

巻号頁・発行日

2016-11-24

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新制・課程博士

著者

高橋 知之 福谷 哲 藤原 慶子 木野内 忠稔 服部 友紀 高橋 千太郎

出版者

京都大学

雑誌

基盤研究(C)

巻号頁・発行日

2012-04-01

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東京電力福島第一原子力発電所の事故では大量の放射性核種が環境中に放出された。このうちTe-127mの半減期は約109日と比較的長く、IAEAの報告書に記載された土壌ー農作物移行係数を用いて評価すると、特に福島第一原発から南方向では、放射性テルルの内部被ばくへの寄与が放射性セシウムに比べて無視できるレベルではない可能性があった。よって、安定テルルと安定セシウムを同時に添加した土壌を用いて植物栽培実験を行い、それぞれの移行係数を求めた。その結果、テルルの移行係数は既報値よりも低く、実際の放射性テルルの線量の寄与は既報値を用いた評価よりも十分に低くなる可能性があることが明らかとなった。