Verification of the sampling procedure for radioactivity analysis of waste and industrial material.

In accordance with ISO/IEC 17025:2017, the testing laboratory needs to verify its ability to properly perform methods. For radiological testing, the sampling does not affect the results directly, but it has to ensure that sample adequately represents the tested material. To verify the procedure, a sampling of red mud and bauxite ore was conducted. All samples were measured in identical geometry by HPGe spectrometer. The counting rates per unit mass in the recorded spectra were compared. For each measurement series, the mean and standard deviations of respected peaks were calculated, as well as average and standard deviation of all series. The obtained results of each individual series were considered satisfactory, i.e. sampling procedure ensures the representativeness of the bulk material, if it is within ± two standard deviations of the average of the mean values.

Distribution of Natural Radionuclides and 137Cs in Urban Soil Samples from the City of Novi Sad, Serbia-Radiological Risk Assessment.

This work presents the natural radioactivity distribution of 21 surface soil samples taken in the city of Novi Sad, Serbia. The analysis for radioactivity was performed using a gas low-level proportional counter for gross alpha and gross beta activity, while the specific activities of radionuclides were determined using HPGe detectors. The gross alpha activity of 20 samples was below the minimum detectable concentration (MDC), while in 1 sample it was 243 Bq kg-1; the gross beta activity ranged from the MDC (11 samples) to 566 Bq kg-1. The gamma spectrometry measurements showed naturally occurring radionuclides 226Ra, 232Th, 40K, and 238U in all investigated samples, with average values (Bq kg-1) of 33.9, 36.7, 513.8, and 34.7, respectively. Natural radionuclide 235U was detected in 18 samples with activity concentrations in the range of 1.3-4.1 Bq kg-1, while in the other 3 samples, the values were below the MDC. The artificial 137Cs radionuclide was detected in 90 percent of the samples, with a maximum value of 21 Bq kg-1, while the other artificial radionuclides were not detected. Based on the obtained concentrations of natural radionuclides, hazard indexes were estimated, and radiological health risk was assessed. The results present the absorbed gamma dose rate in the air, annual effective dose, radium equivalent activity, external hazard index, and lifetime cancer risk.

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.

Intercomparison and performance assessment of radionuclide calibrators used in nuclear medicine departments in Serbia.

The purpose of this work is to assess accuracy and compare the performance of radionuclide calibrators (RNCs) used in nuclear medicine departments in Serbia. Testing of the RNCs included verification of measurement accuracy, as well as analysis of routinely used quality control protocols, by using the certified radioactivity standards (57Co, 137Cs). RNCs performances were assessed with 99mTc through comparison of reference value for radionuclide activity and RNC measurements. Results of the intercomparison revealed that RNCs, 15 in total, are accurate within 10% in vial geometry and within 15% in syringe geometry. Most of them showed similar performance. The results revealed that container geometry is an important influencing parameter in the accuracy of activity measurement. Obtained results indicate a need for regular calibration and implementation of Quality Control program in order to achieve and maintain the accuracy of activity measurements in nuclear medicine.

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.

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).

Coincidence summing corrections for point and volume ¹5²Eu sources.

In this article, the X-ray and gamma-ray coincidence summing effect in (152)Eu is studied. Coincidence summing corrections and peak and total efficiencies of point and volume sources were determined using the direct matrices multiplication (DMM) method. The theoretically evaluated peak count rates were found to be in good agreement with the experimentally obtained values. Validation was performed by comparing the calculated efficiency curves and the corresponding correction factors with the results obtained using GESPECOR 4.2 software.

Vertical distribution of natural radionuclides in soil: assessment of external exposure of population in cultivated and undisturbed areas.

In the present work, naturally occurring radionuclides ²³8U, ²³²Th and 4°K were measured in soil samples from the cultivated and undisturbed areas in Rudovci, municipality of Lazarevac, Serbia. There were three profiles, each profile divided into four horizons, giving the twelve soil samples. The specific activity of ²³8U, ²³²Th and 4°K in soil and sediment samples was determined by gamma spectrometry using the HPGe semiconductor detector. Obtained activity concentrations ranged from 28.0 to 44.0 Bq/kg for ²³8U, from 59.4 to 71.4 Bq/kg for ²³²Th and from 335.0 to 517.0 Bq/kg for 4°K. The evaluation of the radiological hazards originated from ²³8U, ²³²Th and 4°K in the samples, the absorbed dose rate (D) and the annual effective dose rate (E), calculated in accordance with the UNSCEAR 2000 report, are presented in this paper.

Coincidence summing of X- and gamma rays of 75Se.

A study of coincidence summing of X- and gamma rays of (75)Se has been presented in this paper. The computation of the (75)Se spectra was performed by application of the previously published theory by Novkovic et al. The method enables the treatment of all possible single and sum peaks of (75)Se. The calculation gave the 419 decay path outcomes, resulting in 84 peak count rate equations and also the total count rate equation. By HPGe spectrometers with 15% and 18% relative efficiency, 20 and 30 peaks were recorded, respectively. Some simplification of the decay scheme was introduced and existing metastable level had to be treated separately. Nevertheless, the experimental values of the peak count rates were in good agreement with the theoretical evaluation.

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.