Development of a robust and precise methodology for the measurement of the radon diffusion coefficient in diverse materials

Abstract

The main sources of radon indoors are the infiltration from the soil through the building materials and the materials themselves. These pathways are significantly influenced by the radon diffusion coefficient, D, of those elements, playing an important role when trying to mitigate radon accumulation. Current methodologies developed to determine D are difficult to apply. ISO 11665-13 imposes restrictive conditions on the experimental system and requires the application of numerical methods. In the methodology the problem material is placed between a chamber containing a radon source and an empty one and radon concentration is measured in the chambers. The D closer to the experimental data is then selected. In this work, the methodology was improved, and an algorithm was developed to complement the ISO. The algorithm solves for the physical governing equations and finds the value of D that best fits the data by minimising the differences between the predicted and experimental concentrations. Various statistical parameters and stop conditions were studied to determine when an optimal D was found. A validation procedure was developed for internal validation, and results were compared with the literature for external validation. Additional results are presented for materials not found in the literature