van der Spoel W H, van der Graaf E R, de Meijer R J
Nuclear Geophysics Division, Kernfysisch Versneller Institut, Zernikelaan 25, 9747 AA Groningen, The Netherlands.
Health Phys. 1999 Aug;77(2):163-77. doi: 10.1097/00004032-199908000-00006.
Diffusive transport of radon in a moisturized sand column was investigated under well-defined and controlled conditions using a laboratory facility that consists of a cylindrical vessel (height and diameter 2 m) filled with sand. Equilibrium pore-gas radon-concentration profiles in the sand column were measured as a function of depth for several different levels of the ground-water table. The measurements were performed in the framework of a systematic validation study that also covered experiments with dry sand. The experimental data were compared with results of model calculations. Most parameters in the transport model were obtained from separate experiments on small sand samples. In this manner, the radon diffusion coefficient and emanation coefficient were determined as functions of pore-water content, as well as the water-retention characteristics of the sand. In general, the experimental data are reasonably well reproduced by the calculations with differences of 10%-40%. However, with respect to earlier results with dry sand indicating differences of generally smaller than 10%, the agreement between experiment and model for moisturized sand is clearly worse. The main part of the disagreement probably results from inhomegeneities in the sand column that are not accounted for in the transport model.
在一个由装满沙子的圆柱形容器（高和直径均为2米）组成的实验室装置中，在明确界定和可控的条件下，研究了氡在湿润沙柱中的扩散传输。针对几个不同地下水位水平，测量了沙柱中平衡孔隙气氡浓度随深度的分布情况。这些测量是在一项系统验证研究的框架内进行的，该研究还包括干沙实验。将实验数据与模型计算结果进行了比较。传输模型中的大多数参数是通过对小沙样进行单独实验获得的。通过这种方式，确定了氡扩散系数和析出系数作为孔隙水含量的函数，以及沙子的保水特性。总体而言，计算结果能较好地再现实验数据，差异在10% - 40%之间。然而，与早期干沙实验结果（差异通常小于10%）相比，湿润沙实验与模型之间的一致性明显较差。这种不一致的主要部分可能是由于沙柱中的不均匀性在传输模型中未得到考虑。
