Determination of 222Rn Diffusion Coefficient in Japanese Soils

Department of Nuclear Engineering, Graduate School of Enginering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Japan ABSTRACT Radon (Rn) diffusion coefficient as one of some important parameters of Rn transport in the soil has been measured using soil radon diffusion monitor (SRDM). The system of SRDM consists of two scintillation detectors, sample container located between these detectors, photomultiplier tubes, amplifiers, single channel analyzers and personal computer. The source of Rn is put in the one of the compartment, and Rn will diffuse through the sample to other compartment. The diffusion coefficient was determined by calculating the measured data from two detectors using time-dependent diffusion model. The samples come from different places in Japan with several porosities and water contents. The diffusion coefficients were found to vary from (8.68±0.23) x10 ms to (4.39±0.43) x10 ms. Furthermore, the correlations between Rn diffusion and water content and/or porosity are also discussed.