Predrag Škobalj

Environmental radioactivity monitoring represents oneof the key components of public health protection and environmental safety, particularly in areas potentially influenced by nuclear facilities. Continuous monitoring of surface waters, soil, and air enables the timely detection of natural and artificial radionuclides, as well as the assessment of possible radiological impacts on the environment. Special attention is given to river systems that may be exposed to transboundary influences originating from nuclear power plants located along major watercourses. Due to the geographical position of the Republic of Serbia downstream from Nuclear Power Plant Krško and Nuclear Power Plant Paks, surface water radioactivity monitoring constitutes an important part of the national radiological surveillance system. Within the framework of bilateral cooperation between Serbia and Hungary, radioactivity monitoring of the Danube River has been established in the transboundary region at monitoring stations located in Bezdan and Mohács, with the aim of assessing potential radiological impacts and preserving the quality of this international watercourse.

The Republic of Serbia largely meets its electricity needs through production in thermal power plants that use coal as fuel. As the coal-lignite deposits in the Kolubara and Kostolac basins are limited, and the reserves in Kosovo and Metohija are not under the control of the Republic of Serbia, it is necessary to find a solution to ensure the country's energy security and stability. At the end of 2024, amendments to the Law on Energy lifted the moratorium on the use of nuclear energy for peacetime purposes. With this change, the Republic of Serbia gained the opportunity to start a nuclear programme and, with the potential construction of a nuclear power plant, meet its basic energy needs. In this paper, we will analyse the current energy capacities of our country and, based on the experience of selected European countries, examine how it is possible to replace coal-fired thermal power plants with nuclear power plants, the advantages and disadvantages of nuclear power plants, and the obstacles and risks involved in the construction and operation of nuclear power plants.

Phase change materials (PCMs) integrated into lightweight building envelopes were experimentally evaluated to assess their impact on indoor thermal performance. A PCM test house and a reference test house were examined under two conditions: without ventilation and with night ventilation. The experiments were conducted under the climatic conditions of the Republic of Serbia, in Belgrade, at the Vinca Institute of Nuclear Sciences. Two observation periods were defined to evaluate the thermal behaviour of the test houses, with four thermal cycles monitored in each period. Results indicate that, on hot sunny days, the PCM test house achieved maximal indoor air temperature reduction of 3.5-4.8 ?C during the non-ventilated period and 4.2-5.9 ?C during the night-ventilated period, while reducing thermal load levelling (TLL) by 64.1-72.5% and 45.5-49.5%, respectively. The average indoor temperature reduction (AITR) ranged from 0.03-6.12% in the first period and from 3.19-6.54% in the second, confirming the potential of passive PCM application for improving indoor thermal stability. These findings show the practical benefits of PCMs in enhancing energy efficiency and indoor thermal comfort in lightweight buildings.

In addition to the grains as the main agricultural product, the agricultural production of soybean also produces large quantities of plant residues in the form of soybean straw. The article focuses on the primary trends in soybean production worldwide, and Serbian's current position in global production. The paper analysis the dynamics and structure of sown areas, gross harvest volumes and soybean yields in the world for the period 2006-2023 in the context of leading producing countries. Soybean straw is an agricultural leftover that yields up to 1.5 kg per kg of soybeans. The existing literature demonstrates the vast potential of soybean straw as an environmentally friendly source of carbon to produce chemicals, materials, fuels and energy similar to oil refineries. The possibility of using untreated soybean straw for the synthesis of building materials was considered. Different types of common cement were used as starting raw materials for synthesis. The characterization of two test samples was performed using X-ray diffraction analysis (XRD), light microscopy (LM), thermal conductivity and heat capacity measurement.

This paper presents experimental tests of lignite from the Kostolac open-pit mine, used to operate the boiler of the Kostolac B2 thermal power plant in 2022. Experimental tests were conducted to determine the emission characteristics and carbon emission factor and compare these values with those taken and determined in 2016. A total of 31 samples taken in April 2022 were tested. As with our previous work, the experimental methodology includes proximate analysis, ultimate analysis and determination of calorific value, for the ?as received?, ?as determined? and 'dry basis'. Corresponding correlations were established for the tested Kostolac lignite. The emission characteristics of the Kostolac lignite from 2022 were compared with the corresponding values from 2016. Certain changes in the values of the carbon emission factor over time are a regular phenomenon and therefore, periodic sampling and experimental determinations are inevitable to follow the changes in the values. For this change in coal properties, new values for the carbon emission factor are proposed, which should be used to calculate the total carbon dioxide emissions in the last period.