Multilayer Stack Method for Precise Measurement of Radon Diffusion Coefficient of Different Materials

Radon-resistant materials are of great importance for High Background Radiation Areas. Depending on the radon diffusion coefficient, waterproofing and radon-resistant materials with thicknesses ranging from a few microns to several centimeters are used in various parts of the world. The cost of installation of an effective radon mitigation system varied with material properties, i.e., thickness and diffusion coefficient. The present study is concerned with the measurement of the radon diffusion coefficient through single and multilayer homogeneous and heterogeneous stacks of various waterproofing materials. One, two, and three layers of polyethylene, printing paper, mica sheets, PVC sheets, Mylar sheets and aluminum foil of varying thicknesses are tested for determination of diffusion length by the two-chamber method and the active scintillation radon monitor. The radon diffusion coefficient of materials varies from 10^-13m²/s to 10^-8m²/s for PVC sheet to paper sheet when a single layer is used and 10^-11 m²/s to 10^-13 m²/s for aluminum and polyethylene sheets in multi-layer stack arrangement. The radon diffusion coefficient for most of the materials reduces with increasing layers in the stack. By the use of these materials, 85-90 % of radon can be reduced by using single or multi-layer stack combination.