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The geogenic radon potential is primarily controlled by the geological characteristics of the site, such as the rock type and structural elements, as well as the permeability of the soil. Depending on the scope of the survey, the geogenic radon potential can be mapped based on measurements conducted in the field at various resolutions. Detailed surveys are generally labour-intensive and time-consuming. Therefore, a balance should be reached between the desired level of precision and the required amount of effort, delivering the best results with the least number of resources. The international literature describes a variety of surveying techniques. This study was undertaken in a region of the central zone of the Poiana Rusca Mountains (Southern Carpathians, Romania) that contains several metamorphic, volcanic, and sedimentary rock types. The primary objective of the study is to compare alternative sampling point configurations, which vary in number and arrangement. The objective was to achieve the most accurate representation of the calculated geogenic radon potential while limiting the number of measurements and the time and effort associated with them. Radon activity concentration and soil permeability data were collected from 34 locations using seven alternative layouts of the sampling points. The proposed layouts were based on various configurations of fifteen, nine, five, and three sampling points. Locally, in some of the metamorphic units and in the regions containing sedimentary deposits with volcanic intercalations, the geogenic radon potential was found to be elevated. The results indicate that the three-measuring-point configuration is acceptable for general geogenic radon potential surveys.

Schools are a category of public buildings with a high radon exposure risk, due to their high occupancy factor. In Romania, the elaboration of a methodology for radon measurements in schools is a necessity imposed both by the European legislation and by the relatively high percentage (about 10%) of the mapped territory with a potential increased risk of exposure to the action of ionizing radiation emitted by radon. In order to optimize the design of a national survey aimed to evaluate radon exposure of children in Romanian schools, we conducted a pilot study in two schools in Cluj-Napoca, following the screening measurements carried out in 109 schools and kindergartens from five counties. The specific steps that must be followed were described, taking into account the international protocols and particularities of Romanian territory. The proposed approach could act as a guide for other large buildings and is implicit for the implementation of National Radon Action Plan, approved by HG no. 526/12 July 2018 in accordance with Council Directive 2013/59/EURATOM. The obtained results indicate that a high probability of annual radon concentration above the national reference level is to be expected in schools.

Seasonal variations of the radon and radium activity concentrations in karstic water sources originating in karstic formations were investigated as part of a premiere systematic survey conducted in Romania. A database including a total of 228 drinking water samples collected from 30 distinct water sources adjacent to rural communities was compiled. The radon and radium activity concentrations for all seasons, assessed based on solid scintillation, ranged from 2.1 to 19.7 Bq/L and from 0.6 to 3.0 Bq/L, respectively. Overall, the detected radon and radium contents did not exceed the radioprotection standards recommended by national and European legislation. However, in at least one season, the measured values for 31% of the samples exceeded the 11.1 Bq/L maximum contaminant level for radon in drinking water recommended by the Environmental Protection Agency of the United States. The associated radiological risk, reported in terms of annual effective dose, was calculated to be between 9.8 × 10−6 and 6.0 × 10−5 mSv/y for radon and between 5.9 × 10−5 and 2.7 × 10−4 mSv/y for radium, which are considerably below the WHO (World Health Organization) guidelines at a value of 0.1 mSv/y.