Radon soil-gas measurement campaign in Hessen: an approach to identifying areas with enhanced geogenic radon

The new radiation protection law in Germany, which came into effect 2018, puts greater emphasis on the protection against naturally occurring radiation, especially radon as a known health hazard. The law requires the delineation of radon priority areas, where prevention and remediation of high indoor radon concentrations should be taken with priority. In Germany, radiation protection is the administrative responsibility of the federal states. The state of Hesse has early on decided to fully survey the state for radon priority areas. To identify radon priority areas, the geogenic radon potential has to be determined. To achieve that radon, soil-gas measurements combined with soil permeability are a necessity. The University of Applied Sciences (THM) in Giessen is responsible for the radon soil-gas measurement campaign in Hessen. To achieve a statistically sound survey of the state of Hessen with an achievable amount of different measurement locations, and in the given time-frame, a geology-based concept has been designed. Taking into account the known geological information about geological structures in combination with the administrative counties, a survey strategy has been established. Prior known information regarding soil thickness, moisture, digability, and other technical limitations are used to determine the exact measuring locations. At every location, the radon activity in soil gas is measured. The soil permeability is determined for every measurement as well. Three measurements are performed at each location. Having completed the first set of measurements, the design criteria of the campaign and the practical experiences will be presented.