2023 Fiscal Year Annual Research 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 / thoron / active faults / carbon dioxide / permeability / modelling |
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| Outline of Annual Research Achievements |
In our latest field study, the third ever, we confirmed the assumption of elevated radon and thoron concentrations in soil gases surrounding active fault zones. It is worth noting that our measurements revealed a strong correlation between carbon dioxide and radon and thoron concentrations. Conversely, the relationship between radon and permeability showed a weaker correlation.
In addition to field measurements, we also conducted comprehensive laboratory tests of soil samples, including analysis of radionuclide concentrations and various physicochemical parameters. These results were used as input parameters in the advection-diffusion model, enabling a detailed examination of how environmental factors influence radon transport and its subsequent infiltration into homes. The model was applied to multiple scenarios, focusing on typical Japanese house structures.
Our analysis revealed divergent trends between measurement sites. In one site, indoor radon concentrations were strongly influenced by changes in home construction, highlighting the importance of radon-resistant barriers. Conversely, at another site, indoor radon levels were primarily dictated by soil radon concentrations, highlighting the importance of local geological conditions.
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