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This paper aims to estimate a potential radiological risk from different kinds of coals used for domestic heating in Serbia, by measuring the activity concentration of radionuclides and radon exhalation rate. The obtained radon mass exhalation rate ranges from (5.3 ± 3.1) mBqkg–1s–1 to (70.3 ± 9.4) mBqkg –1s–1 and was highest for lignite type of coal. It is estimated that coal stored in the basement could contribute up to 50 Bqm–3 of indoor radon concentration at the ground level. Activity concentrations of 226Ra, 232Th, 40K, 238U, 235U, and 210Pb in analysed coal samples agree with previously reported concentrations of coal used in Serbia. The values of radium equivalent concentration and external hazard index indicate that the used coal does not represent a significant radiation hazard.

The second most important source of indoor radon, after soil beneath dwelling, is building material. With the increase in environmental awareness and new energy-saving policies, residents tend to replace the existing windows with tighter windows, which leads to a decrease in air exchange rate and consequently an increase in indoor radon concentration. In case of low exchange rates, dose caused by inhalation of radon and its progeny can exceed external dose originating from the radium content in the surrounding building material. In this paper, surface exhalation rates of radon (222Rn) and thoron (220Rn) from typical building materials used for construction and interior decoration of houses in Serbia were investigated. Surface exhalation rate measurements were performed using the closed-chamber method, while concentrations of radon and thoron in the chamber were continuously measured using an active device, RTM1688-2, produced by SARAD® GmbH. Finally, the impact of the replacement of windows on the indoor radon concentration was estimated.

Cementation is the baseline technology for conditioning of low to intermediate level radioactive waste. Geopolymers, a class of alkali activated binders, are a promising new material for radioactive waste treatment. Coal fly-ash based geopolymers are a low-cost, low greenhouse gas footprint alternative to metakaolin based materials. Both the grouting of sludge/powders/liquids and encapsulation of solids/compacted waste rely on the grout maintaining optimal flow (rheological properties) during the mixing and pouring operations, and achieving a set leading to proper long term solidification (mechanical properties). The initial and final setting time for fly-ash geopolymer paste, based on the SRPS EN 196-3 standard, has been measured upon irradiation by gamma rays in a 60Co reference field positioned with a kerma air rate of 3.42 mGys–1. The binder paste was prepared using fly-ash from the TENT B power plant's electrostatic filters without further sieving, activated by water glass with module 1.5 and mixed with distilled water until a satisfactory flow was obtained, and poured into the sample and control molds. The initial and final setting times for the irradiated sample and non-irradiated control were determined by the Vicat apparatus. The irradiated sample demonstrated an 11 % shorter initial setting time, and 16 % shorter final setting time, compared to the control.

The possibility of retaining Cs+ and Co2+ bound by immobilization processes in the cement matrix is defined as the subject of its investigation: the cement matrix formulation, the water/cement ratio, the amount of waste, and the porosity of such a structure. Implementing the standard leaching method by Hespe the possibility of comparing different authors' results was achieved. Diffusion and semi-empirical model were used to investigate the transport phenomenon in order to predict the leaching level for a long period of time. Leaching of Co2+ and Cs+ ions under dynamic conditions immobilized in the cement matrix dynamic conditions decreases with the increase of the sludge content, regarding porosity increase. The effects of the diffusion and surface washing are equalized, and the contribution of the matrix dissolution to the Cs+ and Co2+ transport in the cement porous media increases, on average, for one order of magnitude. The semi-empirical model gives a better approximation for Co2+ and Cs+ leaching process for the duration of the experiment while both models significantly approximate leaching results in dynamic conditions. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43009]

The sorption properties of waste facade, brick, and asphalt sample towards Sr(II), Co(II), and Ni(II) ions from single and multicomponent solutions were investigated. The highest sorption capacity was found for Ni(II) ions, while the most effective sorbent was facade. Simplex Centroid Mixture Design was used in order to investigate the sorption processes of ions from solutions with different composition as well as the competition between the cations. Based on the statistical analysis results, the equations for data modeling were proposed. According to the observations, the investigated solid matrices can be effectively used for the liquid radioactive waste treatment. Furthermore, the applied methodology turned out to be an easy and operational way for the investigations of multicomponent sorption processes. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 43009 and Grant no. OI 171007]

In this paper we give an overview of radiation effects in emergent, non-volatile memory technologies. Investigations into radiation hardness of resistive random access memory, ferroelectric random access memory, magneto-resistive random access memory, and phase change memory are presented in cases where these memory devices were subjected to different types of radiation. The obtained results proved high radiation tolerance of studied devices making them good candidates for application in radiation-intensive environments. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 171007]

In recent testing of the partial discharges or the use for the diagnosis of insulation condition of high voltage generators, transformers, cables and high voltage equipment develops rapidly. It is a result of the development of electronics, as well as, the development of knowledge about the processes of partial discharges. The aim of this paper is to contribute the better understanding of this phenomenon of partial discharges by consideration of the relevant physical processes in isolation materials and isolation systems. Prebreakdown considers specific processes, and development processes at the local level and their impact on specific isolation material. This approach to the phenomenon of partial discharges needed to allow better take into account relevant discharge parameters as well as better numerical model of partial discharges.

The aim of this paper is examining a radiation hardness of the magnetic (Toshiba MK4007 GAL) and semiconductor (AT 27C010 EPROM and AT 28C010 EEPROM) computer memories in the field of radiation. Magnetic memories have been examined in the field of neutron radiation, and semiconductor memories in the field of gamma radiation. The obtained results have shown a high radiation hardness of magnetic memories. On the other side, it has been shown that semiconductor memories are significantly more sensitive and a radiation can lead to an important damage of their functionality. [Projekat Ministarstva nauke Republike Srbije, br. 171007]

This paper presents an algorithm for the calculation of internal and external doses as an integral part of the mathematical model of atmospheric dispersion. The air pollution dispersion model is used on average annual activity concentration in the air, deposition on soil and field of total annual dose to a hypothetical resident contaminated by air in the vicinity of a nuclear reactor. The results of modeling were compared with values from an IAEA publication for a given scenario of radionuclide emission to the atmospheric boundary layer. Due to small differences in the results, compared to the IAEA recommended model, the model presented in the paper can be used as a basis for this type of analysis. [Projekat Ministarstva nauke Republike Srbije, br. III 45003, br. III 43009 i br. 171007]

Since the exact time a specific nucleus undergoes radioactive decay cannot be specified, nor can showers caused by secondary cosmic rays be predicted, statistical laws play an important role in almost all cases of experimental nuclear physics. This paper describes the method for the statistical treatment of nuclear counting results obtained experimentally by taking into account random variables pertaining to both frequent and infrequent phenomena. When processing counting measurement data, it is recommended to first discard spurious random variables that spoil the statistics by using Chauvenet’s criterion, as well as to test if the results in the statistical sample follow a unique statistical distribution by using the Wilcoxon rank-sum test (U-test). The verification of the suggested statistical method was performed on counting statistics obtained both from the radioactive source Cs-137 and background radiation, expected to follow the normal distribution and the Poisson distribution, respectively. Results show that the application of the proposed statistical method excludes random fluctuations of the radioactive source or of the background radiation from the total statistical sample, as well as possible inadequacies in the experimental set-up and show an extremely effective agreement of the theoretical distribution of random variables with the corresponding experimentally obtained random variables.

The aim of this paper is to examine the influence of gamma and X-radiation on relevant characteristics of commercial gas filled surge arresters in the d. c. regime. This question is very important because of the wide application of gas filled surge arresters in telecommunications, military industry and space technology. We found that both types of radiation had significant influence on the performance of gas filled surge arresters.