Results of the 2015 national indoor radon intercomparison measurements in Serbia

Results and conclusions of interlaboratory comparison of indoor radon in 2015 in Serbia are presented. The participants were three accredited laboratories from Serbia: Serbian Institute of Occupational Health Dr Dragomir Karajovic, Laboratory for Radioactivity and Dose Measurements at the Faculty of Sciences, University of Novi Sad and Radiation and Environmental Protection Department, Vinca Institute of Nuclear Science. The laboratories make use of the same method for radon measurement, using charcoal canisters according to US Environmental Protection Agency (EPA) protocol 520/5-87-005. Calibration of detection efficiency was performed using EPA radium standard. Radon activity concentrations were determined on the basis of the intensity of short-living radon daughters, Bi-214 and Pb-214, gamma lines. The results of intercomparison were evaluated by using the u-test, which was calculated according to the International Atomic Energy Agency criteria. In this paper, not only limitations but also the advantages and possibilities of application of this method for measuring levels of human exposure to radon are discussed

Correlations between soil characteristics and radioactivity content of Vojvodina soil

During the years 2001 and 2010, the content of U-238, Ra-226, in K-40 and Cs-137 in agricultural soil and soil geochemical characteristics were measured on 50 locations in Northern Province of Serbia - Vojvodina. The locations for sampling were selected so that they proportionately represent all geomorphologic units in the region. The content of clay and humus varied within wide limits depending on soil type and influence the activity concentrations of radionuclides. In this paper we analyzed correlations between radionuclides content and geochemical characteristics of the soil. Possible influence of fertilizers on U-238 content in soil was discussed. The main conclusion is that measured maximal activity concentrations for U-238 (87 Bq/kg), Ra-226 (44.7 Bq/kg), Th-232 (55.5 Bq/kg) and Cs-137 (29 Bq/kg) at 30 cm. depth could not endanger the safety of food production. The process of genesis of soil and cultivation mode plays a dominant role on the characteristics of the soil. The most significant correlation was found between the activity concentrations of K-40 and clay content in agricultural soil

Correlation analysis of the natural radionuclides in soil and indoor radon in Vojvodina, Province of Serbia

The most dominant source of indoor radon is the underlying soil, so the enhanced levels of radon are usually expected in mountain regions and geology units with high radium and uranium content in surface soils. Laboratory for radioactivity and dose measurement, Faculty of Sciences, University of Novi Sad has rich databases of natural radionuclides concentrations in Vojvodina soil and also of indoor radon concentrations for the region of Vojvodina, Northern Province of Serbia. In this paper we present the results of correlative and multivariate analysis of these results and soil characteristics in order to estimate the geogenic radon potential. The correlative and multivariate analysis were done using Toolkit for Multivariate Analysis software package TMVA package, within ROOT analysis framework, which uses several comparable multivariate methods for our analysis. The evaluation ranking results based on the best signal efficiency and purity, show that the Boosted Decision Trees (BDT) and Multi Layer Preceptor (MLP), based on Artificial Neural Network (ANN), are multivariate methods which give the best results in the analysis. The BDTG multivariate method shows that variables with the highest importance are radionuclides activity on 30 cm depth. Moreover, the multivariate regression methods give a good approximation of indoor radon activity using full set of input variables. On several locations in the city of Novi Sad the results of indoor radon concentrations, radon emanation from soil, gamma spectrometry measurements of underlying soil and geology characteristics of soil were analyzed in detail in order to verify previously obtained correlations for Vojvodina soil

Soil-to-plant transfer factor for Sr-90 and Cs-137

This study focuses on determination of soil to plant transfer factor (TF) of long lived radionuclides Sr-90 and Cs-137. Sr-90 and Cs-137 activity concentration in agricultural soil samples was ranged between lt 0.3 and 1.3 Bq kg(-1) and 14 and 30 Bq kg(-1), from lt 2.6 to 7.2 Bq kg(-1) and 5 to 13 Bq kg(-1) fresh matter in roots and from 0.4 to 1.1 Bq kg(-1) and lt 0.2 to 0.7 Bq kg(-1) fresh matter in the rest parts of plant, respectively. Calculated values for Sr-90 and Cs-137 TF from soil to plant ranged from 0.57 to 11.2 and 0.01 to 0.43, respectively