226Ra, 222Rn AND PERMEABILITY OF BELGIAN SOILS IN RELATION WITH INDOOR RADON RISK.

Knowing the concentration of 226Ra in soil and of 222Rn in soil gas is important for the analysis of indoor radon data and the prediction of radon-prone areas. Except for soil Rn in Ardenne, the data concerning these two radionuclides in Belgian soils are very scarce. In the context of Master theses and international courses, students made 92 measurements of 226Ra in soil samples, 105 of 222Rn in soil gas, and 74 of soil permeability, a significant addition to the existing similar data. The data are analysed in relation with soil texture, geological units and indoor radon risk. There is no clear correlation between radium in soil and indoor radon risk, the most important factor of risk being soil permeability.