Comparison and assessment of different radon potential maps for the federal state of Hesse, Germany

With the new Radiation Protection Act, the EU member states are required to identify so-called "radon prone areas". In Germany, the federal states are accounting for this task. An important source of information, inter alia, are maps describing the geogenic radon potential (GRP) provided by the Federal Office for Radiation Protection (BfS). Those maps are modelled using measured radon concentrations and permeabilities as well as geological information. Overall, the availability of such data increased significantly in recent times. Consequently, this has resulted in several versions of GRP maps over the last approx. 25 years. The present study is aiming to assess the evolution of GRP maps available for the federal state of Hesse and to derive “difference maps” that show changes over time. One of the goals is to define the minimum data requirements for a robust prognosis of the GRP. The current GRP map with a resolution of 10 x 10 km is crosschecked with regional geological information in order to reveal possible inconsistencies between the modelled GRP and the geological setting. Finally, for a set of radon measurements underlying the current GRP map of Hesse, soil samples have been taken and analysed regarding their content of Pb214/Ra226 as well as the radon emanation under laboratory conditions in order to investigate if measured concentrations in the field can be explained by in situ conditions. Both regional geological information and soil samples help in the interpretation of the GRP and the difference maps, respectively.