2023 Fiscal Year Final Research Report

Spatial distribution of radon and thoron in the soil around active faults as a contribution to the elevated indoor radon

Research Project

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Project/Area Number	21K12228
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 63010:Environmental dynamic analysis-related
Research Institution	National Institutes for Quantum Science and Technology
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)
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)
Project Period (FY)	2021-04-01 – 2024-03-31
Keywords	radon / thoron / carbon dioxide / soil permeability / radon modelling
Outline of Final Research Achievements	Radon (Rn) is a radioactive gas that naturally emanates from the decay of uranium in soil, rock, and water. It can accumulate in buildings, posing significant health risks, including lung cancer, especially with prolonged exposure. Radon concentrations, along with related parameters such as CO2 levels and soil permeability, were investigated in soil and subsoil near active faults where high radon concentrations may occur. A strong correlation was observed between the distance from the fault and the concentrations of both CO2 and radon. It is suggested that radon is transported from deep layers within the soil by a carrier gas like CO2, and that high soil permeability is due to the fracture structure. Sites were classified based on the radon index (RI), and the geological radon potential was calculated. Due to Japan's geological characteristics, it is expected that more sites will be classified into the high RI zone.
Free Research Field	radiation
Academic Significance and Societal Importance of the Research Achievements	本研究で示した土壌中のラドンや二酸化炭素の濃度と土壌透過性を関連付ける野外調査データは、日本全土の包括的な地質ラドンポテンシャルマップの作成に貢献すると考えられる。このようなマップは、ラドン曝露からの公衆安全を確保するために活用されるとともに、ラドンレベルの潜在的変動を評価するための地質学的ハザード研究に資する。マップ化により高リスク地域であることがわかれば、新しい建物を建設する際に、屋内でのラドンガスの蓄積を防ぐための積極的なアプローチを実施することができるようになる。