The influence of building material structure on radon emanation.

In this work, the radon emanation coefficients for selected building materials that are most often used in Serbia for covering floor surfaces (concrete, concrete screed, granite, glazed ceramic tiles, marble, roofing tile, and terrazzo tile) were determined, and the influence of the material structure on their values. The concentration of226Ra activity in the samples was determined using the gamma spectrometry method. Radon emanation was measured with the RAD7 device. The porosity of the samples was tested using mercury intrusion porosimetry and water absorption methods, and the structural analysis was performed using x-ray diffraction analysis and x-ray fluorescence analysis. The measured values of226Ra activity concentrations were in the range (4.93-298) Bq kg-1, and the estimated values of the radon emanation coefficients were in the range (0.55-6.05) %. The obtained results indicate that the chemical and mineralogical composition, method of production, and the226Ra activity concentration have an influence on the emanation of radon from the material. No significant correlation was found between the radon emanation coefficient and the open porosity of the material, most likely due to the inhomogeneous presence of pores of different dimensions in the materials. It was established that the total value of the emanation coefficient depends on the emanation coefficient for pores ⩽100µm in size.

Results of the first national indoor radon survey performed in Serbia.

The first step in every systematic approach to investigating population exposure to radon on a national level is to perform a comprehensive indoor radon survey. Based on general knowledge of the radon levels in Serbia and corresponding doses, the results obtained from a national indoor radon survey would allow policymakers to decide whether it is necessary to establish a national radon programme. For this reason, Serbia initiated work on a national radon action plan (RAP) in 2014 when it was decided to carry out the first national indoor radon survey. The responsibility for establishing the RAP in Serbia is that of the national regulatory body in the field of radiation protection-the Serbian Radiation and Nuclear Safety and Security Directorate (SRBATOM), formerly known as the Serbian Radiation Protection and Nuclear Safety Agency. The first national indoor radon survey was supported by the International Atomic Energy Agency (IAEA) through a Technical Cooperation Programme. Thanks to the IAEA, we received 6000 passive radon devices based on track-etched detectors. In addition, in order to ensure technical support for the project, SRBATOM formed a task force made up of expert radon representatives from national research institutions. This paper presents a thorough description of the sampling design of the first Serbian indoor radon survey. It also presents the results of the national indoor radon survey, including descriptive statistics and testing of the distribution of the obtained results for log-normality. Based on GPS coordinates, indoor radon data were projected onto a map of 10 km × 10 km grid cells. Two values were calculated for each cell to create two distinct maps. One map shows the arithmetic mean value of indoor radon concentration per grid cell, and the other map shows the number of radon detectors per grid cell used for the calculation of mean values.

Search for 22Na in novae supported by a novel method for measuring femtosecond nuclear lifetimes.

Classical novae are thermonuclear explosions in stellar binary systems, and important sources of 26Al and 22Na. While γ rays from the decay of the former radioisotope have been observed throughout the Galaxy, 22Na remains untraceable. Its half-life (2.6 yr) would allow the observation of its 1.275 MeV γ-ray line from a cosmic source. However, the prediction of such an observation requires good knowledge of its nucleosynthesis. The 22Na(p, γ)23Mg reaction remains the only source of large uncertainty about the amount of 22Na ejected. Its rate is dominated by a single resonance on the short-lived state at 7785.0(7) keV in 23Mg. Here, we propose a combined analysis of particle-particle correlations and velocity-difference profiles to measure femtosecond nuclear lifetimes. The application of this method to the study of the 23Mg states, places strong limits on the amount of 22Na produced in novae and constrains its detectability with future space-borne observatories.

Outdoor Radon as a Tool to Estimate Radon Priority Areas-A Literature Overview.

Doses from the exposure to outdoor radon are typically an order of magnitude smaller than those from indoor radon, causing a greater interest on investigation of the latter for radiation protection issues. As a consequence, assessment of radon priority areas (RPA) is mainly based on indoor radon measurements. Outdoor radon measurements might be needed to guarantee a complete estimation of radiological risk and may help to improve the estimation of RPA. Therefore, authors have analysed the available literature on outdoor radon to give an overview of outdoor radon surveys and potential correlation with indoor radon and estimation of RPA. The review has shown that outdoor radon surveys were performed at much smaller scale compared to indoor radon. Only a few outdoor radon maps were produced, with a much smaller density, covering a larger area, and therefore putting doubt on the representativeness of this data. Due to a large variety of techniques used for outdoor radon measurements and requirement to have detectors with a high sensitivity and resistance to harsh environmental conditions, a standardised measurement protocol should be derived. This is no simple endeavour since there are more applications in different scientific disciplines for outdoor radon measurements compared to indoor radon.

Activity concentrations of 137Cs, 40K, and 210Pb radionuclides in selected medicinal herbs from Central Serbia and their effective dose due to ingestion.

Specific activity of 137Cs, 40K, and 210Pb radionuclides in fifteen selected medicinal herbs from three locations in Central Serbia (two mountains, Kopaonik and Zlatar, and a valley, Sokobanja) was measured using two semiconductor HPGe spectrometer systems. The obtained values are in intervals (<0.3 ÷ 9.7) Bq/kg, (<0.2 ÷ 24.7) Bq/kg, and (<0.2 ÷ 5.7) Bq/kg for 137Cs; in intervals (125 ÷ 1100) Bq/kg, (104 ÷ 872) Bq/kg, and (103 ÷ 954) Bq/kg for 40K, and in intervals (3.6 ÷ 49.0) Bq/kg, (3.9 ÷ 57.9) Bq/kg, and (2.8 ÷ 103) Bq/kg for 210Pb, for herbs from Kopaonik, Sokobanja and Zlatar, respectively. The highest activity measured in individual herbs was: 24.7 Bq/kg for 137Cs (Sokobanja valley), 1100 Bq/kg for 40K (Mt. Kopaonik) and 103 Bq/kg for 210Pb (Mt. Zlatar). The corresponding individual annual effective doses due to ingestion calculated from the measured activity concentrations, of the radionuclides are: in intervals (<1.7 ÷ 82.9) nSv, (<1.4 ÷ 211) nSv, and (<1.1 ÷ 48.7) nSv for 137Cs; in intervals (0.76 ÷ 4.5) µSv, (0.64 ÷ 4.4) µSv, and (0.63 ÷ 4.9) µSv for 40K, and in intervals (1.1 ÷ 18.2) µSv, (1.3 ÷ 21.6) µSv, (0.9 ÷ 38.3) µSv for 210Pb, respectively. The specific activity concentration values of 137Cs and 40K obtained for the investigated herbs are similar to the literature data, while no information was found in literature about specific activity concentration of 210Pb. The all values obtained for individual annual effective dose due to ingestion are less than 100 µSv, which means that the daily use of 200 mL of herbal infusion during a year made from the investigated herbs does not represent a radiological risk for health. However, a high individual annual effective dose of ingestion of 210Pb obtained for some herbs indicate that their consumption in larger amounts 2-3 cups of infusion daily over a year could make the dose to exceed the recommended level, and points to necessity for extensive investigation of 210Pb activity concentration worldwide.

Radon measurements using open-faced charcoal canisters - Measurement uncertainty and method optimization.

Open-faced charcoal canisters have been used for radon measurements for over 40 years. This method is sensitive to temperature, changing radon concentrations, humidity and other parameters, but a comprehensive study dealing with the influence quantities and measurement uncertainty was not available in literature. In this paper, all the identified influence quantities are discussed in detail, uncertainty budget is developed, good practice and bad practice examples are introduced and new recommendations are proposed to optimize the method and reduce uncertainty.

Field experience with soil gas mapping using Japanese passive radon/thoron discriminative detectors for comparing high and low radiation areas in Serbia (Balkan Region).

Based on results of fieldwork in the Balkan Region of Serbia from 2005 to 2007, soil gas radon and thoron concentrations as well as gamma dose rates were measured. Campaigns were conducted in two different geological regions: Niska Banja, considered a high natural radiation area, and Obrenovac around the TentB Thermal Power Plant (TPP), a low natural radiation area. Radon and thoron gas measurements were made by using two types of Japanese passive radon/thoron detectors, which included GPS data and gamma dose rates. The concentrations of soil radon gas in Niska Banja ranged from 1.8 to 161.1 kBq m(-3), whereas the concentrations for soil thoron gas ranged from 0.9 to 23.5 kBq m(-3). The gamma dose rates varied from 70 to 320 nGy h(-1). In the TentB area, radon concentration was found to range from 0.8 to 24.9 kBq m(-3) and thoron from 0.6 to 1.9 kBq m(-3). The gamma dose rate ranged from 90 to 130 nGy h(-1). In addition, the natural radioactivity of the soil was investigated at the low background area. The radium and thorium contents in collected soil samples ranged from 23 to 58 and 33 to 67 Bq kg(-1), respectively. As a result of correlation analyses between the measured values, the highest correlation coefficient (R > 0.95) was found for thorium in the soil and the thoron gas concentration.

Qualitative overview of indoor radon surveys in Europe.

The revised European Directive from 2013 regarding basic safety standard oblige EU Member States to establish a national action plan regarding the exposure to radon. At the same time, International Atomic Energy Agency started technical projects in order to assist countries to establish and implement national radon action. As a consequence, in recent years, in numerous countries national radon surveys were conducted and action plans established, which were not performed before. In this paper, a qualitative overview of radon surveys performed in Europe is given with a special attention to the qualitative and conceptual description of surveys, representativeness and QA/QC (quality assurance/quality control).

EFFECTIVE DOSES ESTIMATED FROM THE RESULTS OF DIRECT RADON AND THORON PROGENY SENSORS (DRPS/DTPS), EXPOSED IN SELECTED REGIONS OF BALKANS.

The main contribution to population exposure is due to radon and thoron progenies and not radon itself. The aim of this study was therefore to estimate annual effective dose using the results of Direct Radon and Thoron Progeny Sensors were exposed in 69 selected schools and 319 dwellings in several regions of Balkans: in Serbia: regions of Sokobanja and Kosovo and Metohija, Republic of Macedonia, Republic of Srpska and Slovenia. Obtained average total effective doses are in the range from 0.22 mSv a-1 (schools in Republic of Srpska) to 2.5 mSv a-1 (dwellings in Kosovo) and are below the reference level of 10 mSv a-1 recommended by International Commission on Radiological Protection.

Traces of DU in samples of environmental bio-monitors (non-flowering plants, fungi) and soil from target sites of the Western Balkan region.

This paper reports results of gamma and alpha spectrometric measurements for mosses, lichens, fungi and soil samples from areas in the Balkans targeted by depleted uranium (DU). Samples were collected in 2002 and 2003 in the vicinity of several villages, principally Han Pijesak (Bosnia and Herzegovina, hit by DU in 1995) and Bratoselce (South Serbia, hit by DU in 1999) and in lesser numbers from Gornja Stubla, Kosovo (which is identified as a high natural radon/thoron area) and Presevo close to the Kosovo border. In the course of gamma spectrometric measurements some results suggested samples with unusual high uranium contents which might be considered to be a signature for the presence of DU, although many samples had very high detection limits. Alpha spectrometric measurements directly proved the presence of DU for five samples, all from directly targeted places. These were samples of mosses, lichens and soil. For some samples homogeneity tests were applied which showed a rather even distribution of DU in these samples. No trace of DU was found in any sample from a dwelling.

Internal exposure from building materials exhaling (222)Rn and (220)Rn as compared to external exposure due to their natural radioactivity content.

The main scope of this paper is to point out the importance of introducing radon and thoron exhalation measurements from building materials in the regulating frame. Currently (2009), such a regulation of this kind of exposure is not explicitly included in the Serbian regulating network. To this end, this work reports concentration measurements of (226)Ra, (232)Th and (40)K and radon and thoron exhalation rates from building materials used in Serbia. Following detailed analysis, it was noticed that both internal exposures to radon and/or thoron exhaling from building materials may exceed external exposures to their precursors contained therein.