Map of natural radioactivity and radon emanation in Slovenia

Maps of contributions of natural radionuclides to the external dose rate in Slovenia are presented. The isodose contours were calculated on the basis of field measurements performed with a four channel NaI spectrometer. A grid 5 km × 5 km was covered by 816 locations. Samples of soil were analysed in the laboratory by Ge-spectrometry and specific chemical methods. Measurements of radon in soil gas show good correlation with equivalent uranium concentrations, with some exceptions in karstic regions. The average natural terrestrial dose rate in air was estimated to be 57 ± 18 nGy/h. Radon-in-soil-gas concentrations are consistent with an average diffusion length of 1 m.