Study on the characteristics of radon exhalation from rocks in coal fire area based on the evolution of pore structure

Preparation and radon exhalation characteristics of fracture granite similar materials in Beishan underground research laboratory

The mechanism of radon exhalation from surrounding rock fracture has important guiding significance for radon prevention and control in underground research laboratories. The optimal ratio scheme of similar materials in the granite surrounding rock of Beishan underground laboratory was obtained by orthogonal test. The radon exhalation characteristics of fractured rock samples under dry and saturated conditions were obtained by using 10 standard joint roughness coefficient (JRC) curves. The radon exhalation rate of the dry sample and the saturated sample is linearly correlated with the JRC grade, and the radon exhalation rate of the dry sample is 82.65 % higher than that of the saturated sample. There was a good correlation between fracture structure parameters (σi, SF, D0) and radon precipitation in fractured rock mass, which is helpful to reveal the mechanism of radon exhalation from fractured rock mass.

Effect of temperature on the radon release characteristics of red clay

Bricks and tiles crafted from fired red clay are extensively utilized in everyday construction activities. However, red clay inherently contains radon gas, a radioactive substance that could potentially endanger human health. Hence, investigating the radon emission patterns of red clay post high-temperature treatment holds significant importance. This study examines the pore structure of red clay following high-temperature treatment through nitrogen adsorption and analyzes the radon release patterns. Findings reveal that the radon release rate from red clay initially rises, then declines with increasing temperature, peaking at 200 °C, registering at 0.0127 Bq/(m2 s). The pore structure significantly influences radon exhalation, with connectivity and micropore volume demonstrating linear correlations with radon exhalation rate, with correlation coefficients of 0.96 and 0.78, respectively. This research offers valuable insights into radon radiation in structures made of red clay.

Study of the influence of pore structure on the radon emission characteristics of terrestrial sedimentary shales after high temperature action

Heat-assisted development of shale oil and gas is recognized as a vital technique for the efficient extraction of shale gas; however, there is a need for comprehensive investigation regarding radon release during the extraction process. The aim of this study was to investigate the pore structure and radon release characteristics of heat-treated black shale using low-temperature nitrogen adsorption (LTNA) and radon (Rn-222) measurement equipment. The findings reveal that temperature initially enhances radon release, which subsequently decreases. The maximum radon release occurs at 500 °C, reaching 1.46 times the initial stage. The radon release rate is positively correlated with the volume of micropores (< 2 nm) in the shale. Organic pores within the shale serve as the primary storage spaces for radon, and the intricate pore structure of organic matter provides an optimal environment for radon gas retention. These results contribute to elucidating the mechanisms behind the impact of thermal treatment on shale's radon release rate, which is crucial for guiding radon radiation evaluation in thermal treatment processes.

Application of airborne geophysical survey data in a logistic regression model to improve the predictive power of geogenic radon maps. A case study in Castleisland, County Kerry, Ireland

In this study, a novel methodology was investigated to improve the spatial resolution and predictive power of geogenic radon maps. The data inputs comprise indoor radon measurements and seven geogenic factors including geological data (i.e. bedrock and Quaternary geology, aquifer type and soil permeability) and airborne geophysical parameters (i.e. magnetic field strength, gamma-ray radiation and electromagnetic resistivity). The methodology was tested in Castleisland southwest Ireland, a radon-prone area identified based on the results of previous indoor radon surveys. The developed model was capable of justifying almost 75 % of the variation in geogenic radon potential. It was found that the attributes with the greatest statistical significance were equivalent uranium content (EqU) and soil permeability. A new radon potential map was produced at a higher spatial resolution compared with the original map, which did not include geophysical parameter data. In the final step, the activity of radon in soil gas was measured at 87 sites, and the correlation between the observed soil gas radon and geophysical properties was evaluated. The results indicate that any model using only geophysical data cannot accurately predict soil radon activity and that geological information should be integrated to achieve a successful prediction model. Furthermore, we found that EqU is a better indicator for predicting indoor radon potential than the measured soil radon concentrations.