Characteristics of radon and thoron exhalation rates in Okinawa, subtropical region of Japan

222Rn and 220Rn surface exhalation rates from earthen building materials used in high background radiation areas of Homa and Ruri, Kenya have been measured using an accumulation chamber coupled with RAD7 detector. Activity concentrations of 226Ra and 232Th in the building materials were determined by γ-ray spectroscopy. In Homa the average 222Rn surface exhalation was 1 ± 0.1 mBqm−2 s−1, while that of 220Rn was 18 ± 2 Bqm−2 s−1; in Ruri 222Rn was 0.9 ± 0.1 mBqm−2 s−1 and 220Rn was 25 ± 3 Bqm−2 s−1. 222Rn was 26 times lower than world average and 220Rn was higher by a factor of 21. Average 232Th in Ruri was 1094 ± 55 Bq/kg, three times that in Homa; 226Ra was 129 ± 10 and 111 ± 6 Bq/kg in Homa and Ruri, respectively. There was a strong correlation between exhalation rate of 222Rn and concentration of 226Ra, as well as between 232Th and 220Rn. Thus, 220Rn was the major contributor to the inhaled dose in earthen dwellings of the two regions.

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Estimation of radon emanation coefficient for representative soils in Okinawa, Japan

Shiroma

Hosoda

Ishikawa

et al. 2015

Radiation Protection Dosimetry

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Radon ((222)Rn) emanation coefficients for the representative soils distributed in Okinawa Island, Japan, have been estimated empirically. Arithmetic means of the emanation coefficients for dry and moist conditions were calculated to be 0.19 and 0.29, respectively. In Okinawa, the soils are traditionally classified into three types, namely the dark red soils, the residual regosols and the red and yellow soils. The dark red soils have relatively high coefficients. The residual regosols and the red and yellow soils have relatively low coefficients. To investigate the variable factor of the emanation coefficients, analyses of radioactive elements and physical properties have also been performed on the soils. For the dark red soils, the contents of the fine particle and the (226)Ra are relatively higher than those for the other soils. Based on these results, it is suggested that the variation in the radon emanation coefficient is mainly regulated by the (226)Ra concentration, the particle sizes and the water contents of the soils.

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Characteristics of radon and thoron exhalation rates in Okinawa, subtropical region of Japan

Cited by 5 publications

References 4 publications

Lung damage by thoron progenies versus possible damage redemption by lung stem cells: a perspective

Lung damage by thoron progenies versus possible damage redemption by lung stem cells: a perspective

Radon and Thoron Exhalation Rates From Earthen Building Materials Used in High Background Radiation Areas of Homa and Ruri, Kenya

Estimation of radon emanation coefficient for representative soils in Okinawa, Japan

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