In situ Measurements of Radon and Thoron Exhalation Rates and Their Geological Interpretation

Hosoda, Masahiro; Shimo, Michikuni; Sugino, Masato; Furukawa, Mutsuhisa; Fukushi, Masahiro

doi:10.5453/jhps.39.206

Cited by 21 publications

(7 citation statements)

References 3 publications

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“…This method was used by many researchers to measure radon emanation coefficient. 25) and HOSODA 26) used an accumulation chamber, air filter, scintillation cell (300A, Pylon, Canada) and its monitor (AB-5, Pylon, Canada) to measure radon mass exhalation rate and radon emanation coefficient.…”

Section: ~18)mentioning

confidence: 99%

Radon Migration Process and Its Influence Factors; Review

Hassan

Hosoda²,

Ishikawa³

et al. 2009

Hoken Butsuri

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Radon (222 Rn) generated within the grains of rocks, soils, building materials and other materials by the radioactive decay of radium ( 226 Ra) can migrate to the atmosphere. This paper reviews the emanation coefficient, diffusion coefficient, and exhalation rate, and the factors that control the rate at which radon can enter atmosphere. The emanation coefficient which is the fraction of radon generated within the grains of materials and escaped to the pore space, varied from 2.1 to 32% for rocks, from 0.14 to 80% for soil, and from 0.10 to 58% in case of building materials. In addition, measurement methods used to evaluate emanation coefficient and its influence factors are also reviewed. The diffusion of radon is a process determined by radon concentration gradient across the radon sources and the surrounding air. The effective diffusion coefficient of some materials is summarized. Moreover, the radon exhalation rate process and the main influencing factors on the variation of exhalation rate data are reviewed. The exhalation rate varied in the range of 0.11 to 80 mBq m -2 s -1 , 2.0 10 -3 to 5.0 10 4 mBq m -2 s -1 and 4.0 10 -3 to 5.0 10 1 mBq m -2 s -1 for rocks, soils and building materials, respectively.

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Section: ~18)mentioning

confidence: 99%

Radon Migration Process and Its Influence Factors; Review

Hassan

Hosoda²,

Ishikawa³

et al. 2009

Hoken Butsuri

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“…Measurements Measurements of radon and thoron exhalation rates have been done using the radon and thoron exhalation rate measuring instrument (MSZ) adopting the accumulation method. Since details of the MSZ have already been reported, 5,13,14) only an outline is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…The results of these studies suggest that regional variation in exhalation rates is mainly controlled by soil characteristics. [5][6][7][8] Much research has been conducted concerning the relationship between the exhalation rates and the soil moisture content, 3,4,9,10) pressure difference in soil air, 11) and effect of rainfall, 12) etc. In this paper, we turned our attention to the relation between the exhalation rates and soil moisture content.…”

Section: Introductionmentioning

confidence: 99%

Effect of Soil Moisture Content on Radon and Thoron Exhalation

Hosoda

Shimo

Sugino

et al. 2007

Journal of Nuclear Science and Technology

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ÃÃIn this study, the authors considered the effect of soil moisture in the emanation process of radon and thoron gases. Weathered granite soil was selected as the test soil and it was packed in a polypropylene container (275 Â 210 mm 2 and 100 mm in height), up to 50 mm in depth from the bottom. The container was covered with the exhalation rate measuring instrument adopting the accumulation method and -particles were counted at 30 s intervals for 30 min to estimate the exhalation rates. A sporadic increase in the radon and thoron exhalation rates was caused by the increase in the moisture content up to 8%. However, the exhalation rates showed a decreasing tendency with the increase in moisture content over 8%. Although the measured radon exhalation rate was about 25% of the calculated one, both measured and calculated radon exhalation rates had similar trends with an increase in the moisture content in the soil. The measured thoron exhalation rate agreed well with the calculated one. When the moisture content was in the range of 3.5-18%, it was considered that applying the correlation between the moisture content and the measured thoron exhalation rate is useful for estimating the thoron effective diffusion coefficient.

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“…Based on the surface geological map of Fukushima Prefecture [ 30 ], loam, granite and black schists are distributed around Nihonmatsu City. The radon exhalation rate from the soil surface, which is one of the influential parameters for outdoor and indoor radon activity concentrations, depends on the surface geology [ 31 , 32 ]. Although the radon exhalation rates were not measured around the measurement points of the indoor radon activity concentrations, the entry of radon exhaled from the soil surface into the residences cannot be completely ruled out.…”

Section: Resultsmentioning

confidence: 99%

A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident

Hosoda¹,

Tokonami²,

Omori³

et al. 2016

Journal of Radiation Research

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Due to the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, the evacuees from Namie Town still cannot reside in the town, and some continue to live in temporary housing units. In this study, the radon activity concentrations were measured at temporary housing facilities, apartments and detached houses in Fukushima Prefecture in order to estimate the annual internal exposure dose of residents. A passive radon–thoron monitor (using a CR-39) and a pulse-type ionization chamber were used to evaluate the radon activity concentration. The average radon activity concentrations at temporary housing units, including a medical clinic, apartments and detached houses, were 5, 7 and 9 Bq m−3, respectively. Assuming the residents lived in these facilities for one year, the average annual effective doses due to indoor radon in each housing type were evaluated as 0.18, 0.22 and 0.29 mSv, respectively. The average effective doses to all residents in Fukushima Prefecture due to natural and artificial sources were estimated using the results of the indoor radon measurements and published data. The average effective dose due to natural sources for the evacuees from Namie Town was estimated to be 1.9 mSv. In comparison, for the first year after the FDNPP accident, the average effective dose for the evacuees due to artificial sources from the accident was 5.0 mSv. Although residents' internal and external exposures due to natural radionuclides cannot be avoided, it might be possible to lower external exposure due to the artificial radionuclides by changing some behaviors of residents.

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In situ Measurements of Radon and Thoron Exhalation Rates and Their Geological Interpretation

Cited by 21 publications

References 3 publications

Radon Migration Process and Its Influence Factors; Review

Radon Migration Process and Its Influence Factors; Review

Effect of Soil Moisture Content on Radon and Thoron Exhalation

A comparison of the dose from natural radionuclides and artificial radionuclides after the Fukushima nuclear accident

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