2021 Fiscal Year Research-status Report
Spatial distribution of radon and thoron in the soil around active faults as a contribution to the elevated indoor radon
| Project/Area Number |
21K12228
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| Research Institution | National Institutes for Quantum Science and Technology |
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Principal Investigator |
Janik Miroslaw 国立研究開発法人量子科学技術研究開発機構, 放射線医学研究所 計測・線量評価部, 研究員 (30833933)
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| Co-Investigator(Kenkyū-buntansha) |
小平 聡 国立研究開発法人量子科学技術研究開発機構, 放射線医学研究所 計測・線量評価部, グループリーダー (00434324)
ゴメス クリストファー 神戸大学, 海事科学研究科, 教授 (20800577)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | radon / active fault / permeability |
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| Outline of Annual Research Achievements |
The sudden and catastrophic or slow and continuous surface release of naturally occurring toxic gases, such as radon or CO2, poses a serious health risk to people living in geologically active regions. Indoor radon activity concentrations, however, vary widely and depend on a variety of factors such as underlying geology, water, weather conditions, and building type. In this project, we seek to understand and estimate radon transport in soil in a region with active faults. The results of this project will 1) help find solutions to mitigate the problem of radon exposure and 2) can be used to apply radon to geohazard studies.
The configuration and validation of the radon and thoron measurement system at the reference point (QST) was completed this year. We developed a new device, called PECAME, for simultaneous measurement of permeability, CO2 and CH4. The PECAME consists of pressure and flow meters, pumps, and sensors to measure CO2 and CH4. Data are collected and stored in memory every one minute using a data logger (GRAPHTEC midi Logger GL220). The PECAME device was tested at a reference site located at the QST campus, and the permeability measurement results were compared with the commercial portable permeability measurement device RADON-JOK. The operating principle of PECAME and RADON-JOK is based on Darcy's law, which describes the flow of fluid through a porous medium.
In addition, subsurface surveys were conducted to identify faults near the active Fugendake volcano (Nagasaki Prefecture) using ground penetrating radar (GRP) and data sets were collected.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
The scope of activities this year was expanded to include the first series of measurements of radon and other parameters on the fault lines south of Mizunashigawa Valley near Unzen Fugendake Peak.
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| Strategy for Future Research Activity |
In the second year, a second measurement campaign will be conducted near Fugendake including radon, thoron, permeability, and GRP measurements to collect more data needed to test the transport model.
A process signal will be developed from the radarogram data (GRP) to include the correction for air travel, then a DEWOW filter, the calculation of the loss of energy with depth depending on the medium and the generation of a time-depth model, in order to correct for the subsurface geometry.
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| Causes of Carryover |
Travel expenses and have been reduced due to COVID-19 travel restrictions. Maintenance of devices was delayed due to COVID-19 problems with on-time transportation. The remaining budget will be used to purchase a better than planned computer for GRP data analysis and for maintenance of radon and thoron measurement equipment.
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Research Products
(1 results)
