Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai-400085, India.
Sci Total Environ. 2011 Jun 1;409(13):2635-41. doi: 10.1016/j.scitotenv.2011.03.031. Epub 2011 Apr 11.
In recognition of the fact that building materials are an important source of indoor radon, second only to soil, surface radon exhalation fluxes have been extensively measured from the samples of these materials. Based on this flux data, several researchers have attempted to predict the inhalation dose attributable to radon emitted from walls and ceilings made up of these materials. However, an important aspect not considered in this methodology is the enhancement of the radon flux from the wall or the ceiling constructed using the same building material. This enhancement occurs mainly because of the change in the radon diffusion process from the former to the latter configuration. To predict the true radon flux from the wall based on the flux data of building material samples, we now propose a semi-empirical model involving radon diffusion length and the physical dimensions of the samples as well as wall thickness as other input parameters. This model has been established by statistically fitting the ratio of the solution to radon diffusion equations for the cases of three-dimensional cuboidal shaped building materials (such as brick, concrete block) and one dimensional wall system to a simple mathematical function. The model predictions have been validated against the measurements made at a new construction site. This model provides an alternative tool (substitute to conventional 1-D model) to estimate radon flux from a wall without relying on ²²⁶Ra content, radon emanation factor and bulk density of the samples. Moreover, it may be very useful in the context of developing building codes for radon regulation in new buildings.
鉴于建筑材料是室内氡的一个重要来源（仅次于土壤）这一事实，人们已经从这些材料的样本中广泛测量了表面氡逸出通量。基于该通量数据，一些研究人员试图预测由这些材料构成的墙壁和天花板释放的氡引起的吸入剂量。然而，在这种方法中没有考虑到一个重要方面，即使用相同建筑材料建造的墙壁或天花板会增强氡通量。这种增强主要是由于氡扩散过程从前者到后者的配置发生了变化。为了根据建筑材料样本的通量数据来预测墙壁的真实氡通量，我们现在提出了一个半经验模型，该模型涉及氡扩散长度以及样本的物理尺寸和墙壁厚度等输入参数。该模型是通过将三维立方体形建筑材料（如砖、混凝土砌块）和一维墙系统的氡扩散方程的解与一个简单的数学函数进行统计拟合而建立的。模型预测已针对新建筑工地的测量值进行了验证。该模型提供了一种替代工具（替代传统的一维模型），可以在不依赖于样本的 ²²⁶Ra 含量、氡散发因子和体密度的情况下，估算墙壁的氡通量。此外，在为新建筑物制定氡法规的背景下，它可能非常有用。
