Radon emanation from soil samples

Abstract The soil or bedrock beneath a building is one of the sources of radon gas in the indoor air. The 238 U content of samples of the soil or the bedrock can be measured by gamma ray spectrometry and is of interest because the uranium content in the soil is a precursor of the presence of the radon gas in the soil. The emanation of radon gas from different types of material can be estimated to some extent if the content of 238 U of a sample is known and the 226 Ra content is only minorly affected. The true emanation is, however, affected by various parameters. One of these parameters is the possibility or not for the gas to come out from the grains into the air in the space between the grains of the sample. In this study we report the results from measurements of radon gas emanating from samples of soil frequent in the Lund region in Sweden and in the Barcelona region in Spain. As soils have different grain size it is important to know the type of soil. The 238 U content of the soil is measured with gamma ray spectrometry. The radon measurements are made by Kodak plastic film in closed cans, filled with the soil according to a technique, developed for radon measurements in water samples. The result shows, that the combination of grain size and uranium content is important for the emanation of the radon gas from the grains of the soil.