The requirements for radiological protection regarding radioactive substances in water intended for human consumption are established in the Council Directive 2013/51/EURATOM of 22 October 2013. In Portugal, the Directive was transposed to the Decree-Law 152/2017, of December 7, which states that the entities managing water supply must establish a quality control program based on a risk assessment. The risk assessment must consider the results of previous monitoring programs of both groundwater and surface water sources and the results of radionuclides measured in raw water, among others.

To aid the entities managing water supply, risk maps of radon (Rn-222), uranium (U-238 and U-234), radium (Ra-226) and polonium (Po-210) were developed for mainland Portugal by the Laboratory of Natural Radioactivity of University of Coimbra using: (i) results from measurements performed in water samples retrieved from the database of the national regulation authority responsible for water and waste services (ERSAR); (ii) the terrestrial gamma dose rate map at the scale of 1:1 000 000; (iii) uranium concentration (n = 2681) and (iv) radium activity concentration (n = 609) measured in bedrock samples. ERSAR’s database comprises radon (n = 9473), gross alpha and beta (n = 10500), Po-210 (n = 1188), Ra-226 (n = 1143), U-234 (n = 1127) and U-238 (n = 1129) results from 5874 distinct groundwater and surface water sources. In this work, data are presented, methods and challenges for risk mapping of radon and terrestrial radionuclides in water samples are discussed.

Radon (Rn)is a naturally occurring, radioactive gas that is considered an indoor air pollutant. Due to its negative effects on human health, a Germany-wide "Radon Potential Action Plan" was implemented based on the European Directive for Radiation Protection (2013/59/Euratom).

As part of this action plan, areas with high geogenic Rn potential (GRP) need to be determined and surveyed. GRP is based on the measured soil gas Rn concentration and the soil gas permeability indicating higher availability of Rn and hence, a higher potential for elevated indoor Rn concentration. Based on former studies of the Federal Office for Radiation Protection, a medium-to low GRP for the state of Hesse was estimated. Locally high variations in the south are found, primarily due to the Odenwald-Mountain-Range.

Based on the geological diversity and its major impact on the GRP, this study tried to include geological small-scale variations, to estimate an urban GRP map for Darmstadt. For this, 134 measurements of soil gas Rn concentration were used as well as a soil gas permeability map with a resolution of 100 km². The geological classification is based on the Hessian geological map 1:25 000, showing 55 petrographic classes for Darmstadt, from which 16 are represented by GRP calculations showing the highest GRP for silt with 41.39. The other classes are following the tendency that acidic plutonic rocks show higher GRP (18.4), metamorphic rocks medium (10.1), and clastic sediments lower GRP (6.1).

It is a well-known fact that the city of Cluj-Napoca in Romania has a diverse geological stratification, based on the geological data and studies performed on the soil by geologists. Also, the measurements and studies performed of radon in soil conclude the fact that in certain parts, the geological formations lead to a higher concentration of geogenic radon, thus making the soil in this area a radon prone hotspot. The following presentation aims to show the correlations between the radon prone geological areas and the accumulation of high concentrations (indoor radon) in different types of buildings, regarding a few examples of residential buildings like houses and big building categories such as public institutions. The studies performed so far show different accumulation between buildings, but even the way that certain buildings were built in the same area where the soil has a high radon potential. This shows that even if the population builds in high radon prone areas, there is a way to build buildings, following radon building guidelines to limit the diffusion of radon trough out the foundation of the building or even blocking it completely.

There are three key factors when talking about a high radon concentration risk exposure indoors, that are the following: the radon potential in the soil where the building is built, the way and techniques used to build the certain building and the way the building is used on a daily bases.

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.

Ukraine is known as a uranium mining country located in the Central-Eastern Europe. The authors have been studying radioecological situation within the Central Ukrainian Uranium Province where the uranium deposits are located (operated, dormant and perspective ones) for more than 10 years already. Radioecological research, including the radon emanations from soils, allowed us allocating radon-hazardous areas associated with uranium mineralization.

The recently studied Mykhailivska ore area (south-eastern part of the Ukrainian Shield) is a unique one in terms of the location of two different types of uranium deposits here. One type is an endogenous deposit represented by the main ore body and almost 20 smaller ore anomalous. The other type belongs to exogenous infiltration uranium deposits type of Paleogene epoch uranium ore formation. The area of 15 km x 20 km was explored and more than 150 measurements of radon flux density (RFD) were made.

The measurement RFD is based on the determination of the activity of radon accumulated due to the inflow of a known area from the soil surface, in a measuring chamber or sampler during pumping with a blower for 5 minutes. The exposure time of one sample is 20 minutes. Areas adjacent to uranium ore manifestations are characterized by increased levels of radon exhalation, which is typical for areas containing uranium minerals.

High and average radon-prone areas were outlined and maps of radon anomalies prepared.

Geological interpretation is supposed to be used while further planned uranium extraction through method of underground leaching within the researched territory.