Characterization of rock fractures for fractal modeling of radon gas transport

Abstract

Enhancing the predictability of radon flux in fractured environments, particularly in confined spaces, is a crucial step towards mitigating the profound health risks associated with radon gas exposure. However, previous models on fluid transport through fractured rock have focused on the relationship between radon flux and aperture in fractures and faults. However, there is paucity of understanding on the influence of rock geo-mechanical properties on radon flux. In addition, there are limited methods of characterizing rocks in relation to radon flux. The numerical model presented in this study incorporated rock properties such as Young's modulus and Poisson ratio with rock aperture to develop a dimensionless radon flux for opening-mode fractures, and five dimensionless parameters (e.g., Geofluid number, Decay number, Fracgen number, Geofrac number, and Geopeclet number) were introduced to characterize fractures in terms of radon transport. Furthermore, these newly discovered relationships were used to conduct a series of flow simulations on fracture networks using the discrete fracture network model (DFN). This model establishes a quantitative framework for predicting radon flux through open-mode fractures and the influence of rock geo-mechanical properties.