engleski

THE NATURAL RADIOACTIVITY OF ISTRIA (CROATIA)

Because of the geological structure of Istrian peninsula which mainly consists of a limestone that is characterized by karstic topography on its surface, it is expected that there are areas with elevated radon levels in soil gas as well as inside buildings (e.g. houses, kindergartens, schools). Recently, from autumn 2013 until spring 2015, radon measurements at more than 1000 randomly selected locations (in houses as well as in schools and kindergartens) were investigated. The average value of indoor radon in homes is 102 Bq m-3 while the average radon concentrations in kindergartens and schools are two times higher than in homes. In fact, 24% of kindergartens and 40% of schools have, at least, one room/classroom with radon value higher than 300 Bq m-3 which is the maximum reference level in EU and Croatia. Radon concentrations in soil gas in Istrian peninsula were measured from 2013 to 2015 with the AlphaGUARD and RM-2 measuring systems. The obtained average value of 103 kBq/m3 classifies the soil of Istria County into soil of high geogenic radon potential. It is important to emphasize that there are areas with radon concentrations up to 500 kBq m3. Soil samples were collected according to the standard procedures of the IAEA at 55 different locations. Activity concentrations of selected radionuclides were determined by means of gamma spectrometry by using an ORTEC HPGe detector system. The correlation between radon and thoron soil gas and their parents radium/uranium and thorium were investigated. In accordance with the obtained results, areas with elevated indoor radon levels as well as levels of radon in soil gas were identified and radon maps were generated by using different geostatistical approaches.

national survey of indoor radon

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