Measurements of thoron progeny concentration using a potential alpha-energy monitor in Japan.
It is reported that thoron concentration in Japanese dwellings may be higher than in other dwellings. Therefore, in order to assess the risk for indoor thoron progeny, the portable potential alpha-energy monitor has been developed. The monitor detects alpha-particles from the 212Po collected on the filter using a piece of cellulose nitrate film. The detection efficiency of the alpha-particles has been estimated by Monte Carlo calculation. From the results of measurements, the mean indoor thoron progeny concentration in the dwellings was 1.5 Bq m-3 (ECTn), and ranged from 0.04 to 8.2 Bq m-3. The effects of three typical interior walls (soil-based plaster, concrete, and modern materials) on the thoron progeny supply were considered. The mean annual effective dose equivalent was 0.45 mSv.
Yamasaki
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Chubu Electric Power Company, Inc., Nagoya, Japan.
Iida
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D000396:Air Pollutants, Radioactive / Q000032:analysis; D016902:Air Pollution, Indoor / Q000032:analysis; D000512:Alpha Particles; D055592:Biophysical Phenomena; D001703:Biophysics; D006798:Housing; D006801:Humans; D007564:Japan; D011834:Radiation Monitoring / Q000295:instrumentation*; D011886:Radon / Q000032:analysis*
D000396:Air Pollutants, Radioactive; D011886:Radon