Gordana K. Pantelić

Validation of Radiochemical Method for the Determination of 90Sr in Environmental Samples

The proposed and validated method for determination of 90Sr content in environmental samples (water, soil and plant) is based on the radiochemical analytical separation of 90Y from the sample and measuring its activity after the establishment of radioactive equilibrium with 90Sr. Validation is the confirmation by examination and provision of objective evidence that they meet the individual requirements stipulated for a specific use. Validation of method was done based on the blank samples for water by adding 90Sr known activity and using reference materials of soil (IAEA-326) and plant (IAEA-330). Content of 90Sr in environmental samples was determined by α/β low level proportional counter. The accuracy and the precision of the applied method are confirmed and the method is validated and can be used for determination of 90Sr in environmental samples. On the other hand, participations in interlaboratory comparisons are confirmed that the adequacy of the validated method is ensured.

137Cs and 40K in some traditional herbal teas collected in the mountain regions of Serbia

Herbal teas are an important part of traditional medicine in Serbia. The objective of the present study was to determine the activity concentrations of 40K and 137Cs in herbal tea, using the gamma spectroscopy method. The samples were collected during the period 2011–2012 in three mountain regions in Western and Central Serbia. The activity concentrations of 40K and 137Cs were found to be in the range of 130–1160 and 0.7–124 Bq kg−1, respectively. The average annual effective dose equivalents from ingestion of 40K and 137Cs for an adult person consuming one cup of herbal tea daily were found to be 588.4–5250.2 nSv for 40K and 4.0–706.1 nSv for 137Cs. Our investigation showed that the herbal teas originating from Maljen, Zlatibor and Tara mountains are radiologically safe for human consumption.

Uncertainty evaluation in radon concentration measurement using charcoal canister.

Active charcoal detectors are used for testing the concentration of radon in dwellings. The method of measurement is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. The contributions to the final measurement uncertainty are identified, based on the equation for radon activity concentration calculation. Different methods for setting the region of interest for gamma spectrometry of canisters were discussed and evaluated. The obtained radon activity concentration and uncertainties do not depend on peak area determination method.

AD-HOC INTERCOMPARISON OF FOUR DIFFERENT RADON EXHALATION MEASUREMENT METHODS

It is indicated that the exposure to radon originating from the building materials is not negligible and the radon exhalation measurement should get more attention in the future. The experience with four different methods of the exhalation measurement, established in our laboratory for the purpose of the intercomparison is reported. Additionally, a comparison of advantages and disadvantages of used methods is discussed.

First steps towards national radon action plan in Serbia

Abstract Radon problem has a special attention in many countries in the world and the most of them have established national radon programmes. The radon issues in Serbia have not been approached in a systematic and organized way. Currently, there are many research groups and institutions working in radon field, and it is a good basis to integrate all these activities into a comprehensive national programme to define the strategic objectives and action plan for the next few years. Also, Serbia as a candidate for membership in the EU is obliged to harmonize its legislation, including the field of radiation protection in which the radon issues has an important role. In this report, a brief history of radon research, present status and plans for the future activity on radon issues in Serbia are presented. Regarding the long-term plans, the establishment and implementation of the Radon Action Plan with the primary goal of raising awareness about the harmful effects of public exposure to radon and implementing a set of measures for its reduction. In that sense, the synergy between the national, regional and local organizations responsible for public health and radiation protection must be achieved.

Semiempirical Efficiency Calibration in Semiconductor HPGe Gamma-Ray Spectroscopy

One of the main problems in quantitative gamma-ray spectroscopy is the determination of detection efficiency, for different energies, source-detector geometries, and composition of samples or sources. There are, in principle, three approaches to this issue: experimental, numerical, and semiempirical. Semiempirical approach is based on the calculation of the efficiency for the measured sample on the basis of an experimental efficiency measured on the same detector, but with a calibration source that can be of different size, geometry, density, or composition—the so-called efficiency transfer. The aim of this paper is to analyze the semiempirical approach, using EFFTRAN and MEFFTRAN software as a typical example. These software were used in the Department of Radiation and Environmental Protection, Vinca Institute of Nuclear Sciences, on three HPGe detectors. The results were compared to the experimentally obtained efficiency, and further validation is performed by measuring reference materials issued within the framework of several interlaboratory intercomparisons. The analysis of the results showed that the efficiency transfer produces good results with the discrepancies within the limits of the measurement uncertainty. Also, for intercomparison measurement, utest criterion for the trueness of the result was applied showing that the majority of the obtained results were acceptable. Some difficulties were identified, and the ways to overcome them were discussed.

Results of the 2015 national indoor radon intercomparison measurements in Serbia

Abstract 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 Karajović”, Laboratory for Radioactivity and Dose Measurements at the Faculty of Sciences, University of Novi Sad and Radiation and Environmental Protection Department, Vinča 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, 214Bi and 214Pb, 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.

Interlaboratory comparison material homogeneity testing

Abstract The homogeneity of fertilizer samples for interlaboratory γ-ray spectrometry comparison was tested by determination of the total γ count rate and the count rates for two 238U γ lines, one 40K line and one common 235U and 226Ra line. Homogeneity testing was accomplished by determination of the minimum, maximum, mean and standard deviation for each parameter and comparison of their standard deviations with predefined tolerances, by Cochran’s test, and by a one-way ANOVA. The standard deviations were all less than these tolerances. All samples passed Cochran’s test and the one-way ANOVA test for homogeneity. Graphical Abstract

Comparison of two different methods for grossalpha and beta activity determination in watersamples

Abstract Measurement of the gross alpha and beta activity concentrations in various matrices is suitable as a preliminary screening procedure to determine whether further analysis related to specific radionuclide is necessary. In Serbia, according to current regulations, radioactivity concentrations in drinking water for gross alpha and gross beta should be < 0.5 and < 1.0 Bq L−1, respectively. The generally accepted methods for gross alpha and beta activity analysis of drinking water in different countries are: EPA 900.0 and ISO methods (ISO 9696, water quality – measurement of gross alpha activity in non-saline water – thick source method, and ISO 9697, water quality – measurement of gross beta activity in non-saline water). This paper describes comparison of preparations and measurement gross alpha and beta activity in bottled mineral waters as well as in tap waters in Serbia using two methods: EPA 900.0 with and without ash, and ISO methods. Concentration of total dissolved solids (TDS) in investigated water samples was determined. Based on obtained TDS, certain volume was evaporated. The instrumentation used to count the gross alpha and gross beta activities for both methods is α/β low level proportional counter Thermo Eberline FHT 770 T. Graphical Abstract

Comparison of two methods for high purity germanium detector efficiency calibration for charcoal canister radon measurement

The charcoal canister method of radon measurement according to US Environment Protection Agency protocol 520/5-87-005 is widely used for screening. This method is based on radon adsorption on coal and measurement of gamma radiation of radon daughters. For the purpose of gamma spectrometry, appropriate efficiency calibration of the measuring system must be performed. The most usual method of calibration is using standard canister, a sealed canister with the same matrix and geometry as the canisters used for measurements, but with the known activity of radon. In the absence of standard canister, a different method of efficiency calibration has to be implemented. This study presents the results of efficiency calibration using the EFFTRAN efficiency transfer software. Efficiency was calculated using a soil matrix cylindrical secondary reference material as a starting point. Calculated efficiency is then compared with the one obtained using standard canister and applied to a realistic measurement in order to evaluate the results of the efficiency transfer.