Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air
Thoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron in...
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doaj-26284e1c69a444c3b74b90c1c09402ad2020-11-25T03:33:08ZengMDPI AGInternational Journal of Environmental Research and Public Health1660-46012020-02-0117397410.3390/ijerph17030974ijerph17030974Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer AirYasutaka Omori0Michikuni Shimo1Miroslaw Janik2Tetsuo Ishikawa3Hidenori Yonehara4Department of Radiation Physics and Chemistry, Fukushima Medical University, 1 Hikarigaoka, Fukushima 960-1295, JapanFujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake, Aichi 470-1192, JapanCenter for Advanced Radiation Emergency Medicine, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, JapanDepartment of Radiation Physics and Chemistry, Fukushima Medical University, 1 Hikarigaoka, Fukushima 960-1295, JapanNuclear Safety Research Association, 5-18-7 Shimbashi, Minato-ku, Tokyo 105-0004, JapanThoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron interference. Rates of thoron infiltration (as thoron interference) into the diffusion chamber of the monitor were evaluated. The temporal variation was obtained based on measurements of the underfloor space of a Japanese wooden dwelling using a diffusion-type radon monitor, a reference radon monitor which was not affected by thoron interference, and a thoron monitor. The thoron infiltration rate for the diffusion-type monitor varied from 0% to 20%. In particular, it appeared to increase when ventilation of the underfloor space air was forced. The variable thoron infiltration rate, with respect to ventilation strength, implied that not only a diffusive process, but also an advective process, played a major role in air exchange between the diffusion chamber of the monitor and the outer air. When an exposure room is characterized by the frequent variation in air ventilation, a variable thoron response is considered to occur in radon−thoron discriminative detectors, in which only diffusive entry is employed as a mechanism for the discrimination of radon and thoron.https://www.mdpi.com/1660-4601/17/3/974air exchangediffusionfilterinfiltrationpassive monitorradonthoron interferenceventilation |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yasutaka Omori Michikuni Shimo Miroslaw Janik Tetsuo Ishikawa Hidenori Yonehara |
spellingShingle |
Yasutaka Omori Michikuni Shimo Miroslaw Janik Tetsuo Ishikawa Hidenori Yonehara Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air International Journal of Environmental Research and Public Health air exchange diffusion filter infiltration passive monitor radon thoron interference ventilation |
author_facet |
Yasutaka Omori Michikuni Shimo Miroslaw Janik Tetsuo Ishikawa Hidenori Yonehara |
author_sort |
Yasutaka Omori |
title |
Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air |
title_short |
Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air |
title_full |
Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air |
title_fullStr |
Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air |
title_full_unstemmed |
Variable Strength in Thoron Interference for a Diffusion-Type Radon Monitor Depending on Ventilation of the Outer Air |
title_sort |
variable strength in thoron interference for a diffusion-type radon monitor depending on ventilation of the outer air |
publisher |
MDPI AG |
series |
International Journal of Environmental Research and Public Health |
issn |
1660-4601 |
publishDate |
2020-02-01 |
description |
Thoron interference in radon measurements using passive diffusion radon detectors/monitors is a crucial problem when it comes to assessing the internal exposure to radon precisely. The present study reported, as one of the potential factors, the effects of air flow conditions on changes in thoron interference. Rates of thoron infiltration (as thoron interference) into the diffusion chamber of the monitor were evaluated. The temporal variation was obtained based on measurements of the underfloor space of a Japanese wooden dwelling using a diffusion-type radon monitor, a reference radon monitor which was not affected by thoron interference, and a thoron monitor. The thoron infiltration rate for the diffusion-type monitor varied from 0% to 20%. In particular, it appeared to increase when ventilation of the underfloor space air was forced. The variable thoron infiltration rate, with respect to ventilation strength, implied that not only a diffusive process, but also an advective process, played a major role in air exchange between the diffusion chamber of the monitor and the outer air. When an exposure room is characterized by the frequent variation in air ventilation, a variable thoron response is considered to occur in radon−thoron discriminative detectors, in which only diffusive entry is employed as a mechanism for the discrimination of radon and thoron. |
topic |
air exchange diffusion filter infiltration passive monitor radon thoron interference ventilation |
url |
https://www.mdpi.com/1660-4601/17/3/974 |
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