Assessment of radon potential of soils—A five-year experience

Abstract The uniform method for the assessment of radon potential of soils (so-called Radon Risk Classification of Foundation Soils) used in the Czech Republic is based on determination of soil-gas radon concentration and on permeability classification. This paper discusses the results of studies to improve the method based on recent experience. The soil-gas radon concentrations may vary, often greatly, over small distances. An occurrence of heterogenities often indicates the presence of faults or tectonic zones. Any evaluation based on a single measurement is almost worthless. The sampling depth of 0.8 m represents a reasonable compromise between the required reduction of errors caused by the radon variability and the practicability of the method under field conditions. Observed temporal variations of soil-gas radon concentrations may often correspond not only to real variations of the measured physical quality, but also to fluctuations and errors connected with the sampling and measuring technique. A reproducibility of the radon risk classification is satisfactory. Neither a normal nor a log-normal model is generally applicable for a description of soil-gas radon concentration data. The field of soil-gas radon concentration measurement is characterized by a relatively high level of knowledge. More problems are connected with the determination of the second main parameter-soil permeability.