著者

Kazuhisa Nakazato

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.61-80, 2013 (Released:2013-12-19)

参考文献数

20

被引用文献数

2

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A huge amount of radioisotopes(RI), such as 132Te, 131I, 134Cs and 137Cs etc., was released into the atmosphere by the accident of Fukushima Daiichi nuclear power plant of Tokyo electric power company. According to the news immediately after the Fukushima nuclear accident, it was reported that almost all clothes were largely contaminated with the RI, confirmed by the early screenings of the general public evacuated from the Fukushima nuclear accident. On account of a worry about the RI contamination on clothes, many inhabitants could not dry their clothes out of doors in an area indicated the high radiation dose caused by the RI contamination in both Fukushima prefecture and some prefectures next to Fukushima prefecture even after the accidental release of RI was stopped from the accidental Fukushima nuclear power plant.   In order to settle this situation effectively, the Ad Hoc Committee on Safety Measures against Radioactive Iodine and Cesium of the Japanese Society of Radiation Safety Management (JRSM) established a clothes analysis group. The Clothes Analysis Group aimed to analyze the actual RI contamination on clothes, and to develop a simple method to remove the RI by using washing machine sold on market, and so on.   The results were summarized as follows;   (1) The RI contamination was recognized obviously on clothes worn around the accidental Fukushima nuclear power plant immediately after the accident. However, on the clothes worn at July 2011, the RI contamination was not detected by a survey meter, but was detected a little by a Ge semiconductor detector.   (2) The RI on clothes was decontaminated easily by a wash using a usual washing machine and detergent sold on the market. The RI decontamination ratios of the March clothes and the July one in 2011 were approximately 84 % after three times wash and 88 % after a once, respectively.   (3) Radioactive Cs remained slightly after the wash and attached a little on clothes dried out of doors. Whenever the public lived in Fukushima prefecture might wear continuously the clothes contaminated by a trace of Cs after the wash and drying outside, the radiation safety was sufficiently confirmed because the estimated effective dose rate would be extremely lower than the annual dose limit.   Consequently, the wash by using a commercial washing machine and detergent was useful and easy for removing the RI from clothes without a special apparatus for the RI decontamination. Furthermore, the wash was effective both for eliminating an anxiety over radiation exposure by wearing the contaminated clothes, and for bringing a feel of relief by wearing the clean washed clothes.