Scientific peer-reviewed journal "NNC RK Bulletin"
Национальный ядерный центр Республики Казахстан
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ANALYSIS OF THE STRUCTURE OF POLLUTANT EMISSIONS IN THERMAL POWER ENGINEERING: A CASE STUDY OF AN OPERATING ENTERPRISE
The article presents an analysis of the structure of pollutant emissions from boiler units of a coal-fired combined heat and power plant using the example of CHPP-1 in the city of Semey. The study is based on operational and inventory data for 2024, reflecting the actual operating conditions of the equipment. Quantitative characteristics of emissions of major pollutants and their distribution between steam and hot water boilers were determined. The analysis showed that gaseous pollutants dominate the structure of emissions – nitrogen dioxide, sulfur dioxide, carbon monoxide, and nitric oxide – with a total share exceeding 95% of the annual emissions. Among solid pollutants, the largest share belongs to inorganic dust with a high content of silicon dioxide, while the contribution of other substances remains insignificant. The quantitative assessment of the emission structure made it possible to determine the actual contribution of each type of equipment to the total level of air pollution. The findings provide a basis for designing targeted strategies to reduce air pollution at thermal power plants, optimize environmental monitoring systems and improve the performance of flue gas cleaning equipment, thereby supporting the sustainable operation of energy facilities.
MICROWAVE SYNTHESIS OF ELECTRODE MATERIAL FROM TEA BIOMASS FOR ENERGY STORAGE SYSTEMS
This article focuses on the production of a carbon material from tea waste for energy storage systems and the investigation of its properties. The synthesis process was carried out via microwave carbonization followed by physical activation in a CO₂ atmosphere. The morphological and structural characteristics of the samples were determined using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. The synthesized activated carbon exhibited high porosity and appreciable electrical conductivity. XRD analysis revealed diffraction peaks at (002) and (100), indicating a tendency of the obtained carbon material to form a graphite-like structure. In the Raman spectrum, the D (≈1350 cm⁻¹) and G (≈1580 cm⁻¹) bands were observed, indicating the presence of defects and graphitic domains within the carbon structure. The intensity ratio ID/IG was 0.73, suggesting a relatively well-ordered structure. The electrochemical properties of the activated carbon derived from tea waste were investigated using cyclic voltammetry, galvanostatic charge-discharge cycling, and electrochemical impedance spectroscopy. According to the results, the specific capacitance of the carbon material reached up to 116 F/g at a current density of 500 mA/g. These findings confirm the promising potential of carbon materials derived from biomass for use in supercapacitors and their effectiveness in enhancing energy storage device performance.
THE STUDY OF THE ANTIMICROBIAL PROPERTIES OF THE RADIOPHARMACEUTICAL 18F-FDG
Ensuring sterility is a prerequisite for the clinical use of radiopharmaceuticals (RPs), as any breach is associated with risks to patient health. This requirement is particularly important for intravenously administered drugs, such as 18F-fluorodeoxyglucose (18F-FDG), which is widely used in clinical practice for positron emission tomography (PET). The uniqueness of 18F-fluorodeoxyglucose lies not only in its diagnostic value but also in the specific requirements for its production and quality control, due to the short half-life of the radionuclide 18F. In this regard, the question arises as to whether the intrinsic ionizing radiation of the drug may possess antimicrobial potential and contribute to ensuring its microbiological safety. Assessment of the drug’s ability to suppress the viability of microorganisms that may potentially overcome standard aseptic manufacturing conditions and sterilization is aimed at reducing the risks of microbial contamination and increasing patient safety, which is particularly important for immunocompromised patients. The present study is aimed at the experimental investigation of the hypothesis to determine whether the drug has, and to what extent, the ability to exert antimicrobial action by virtue of its own ionizing radiation. To carry out an experimental assessment of the ability of the radiopharmaceutical 18F-fluorodeoxyglucose to suppress the viability of microorganisms, depending on the activity of the 18F radionuclide. An experimental study was performed to evaluate the inhibitory activity of 18F-fluorodeoxyglucose (18F-FDG) against the sanitary-indicative microorganism Bacillus subtilis (ATCC: 6633). Antimicrobial action was assessed by the direct inoculation method into fluid thioglycollate medium. 1 mL of the radiopharmaceutical with varying activity levels (200–1400 MBq) was added to test tubes. Control samples included: sterile medium, physiological solution, and “cold” fluorodeoxyglucose (F-FDG) with a stable fluorine isotope. The intensive growth of culture was observed in the control: medium. In an experiment with 18F-fluorodeoxyglucose, there was a growth ‘gradient’ of the culture, depending on the levels of radionuclide activity. Based on the obtained data, the 18F-labeled radiopharmaceutical, in the activity range of 200-1400 MBq, does not have significant antimicrobial activity against Bacillus subtilis. The obtained results showed that the investigated range of activities (200-1400 MBq) does not ensure complete suppression of culture growth. Thus, in manufacturing, aseptic synthesis must be strictly observed in addition to the final sterilization of radiopharmaceuticals. Further investigation is ongoing.
ATOMISTIC SIMULATION OF HYDRONIUM ION INTERACTIONS WITH POLYSULFOBETAINE: INSIGHTS FOR PROTON EXCHANGE MEMBRANE ENVIRONMENTS
The ongoing shortcomings of existing proton exchange membranes (PEMs), which frequently have poor ionic conductivity and insufficient chemical stability under operating circumstances, seriously impede the development of fuel cell technology. Research has concentrated on creating innovative polymeric materials with improved proton transport and strong molecular frameworks in order to address these issues. The use of polysulfobetaine (PSB), a zwitterionic polymer, is suggested in this work as a viable option for next-generation PEMs because of its capacity to form hydrophilic proton-conducting channels while preserving structural integrity. We used Density Functional Theory (DFT) simulations to study the fundamental interactions between a hydronium ion (H₃O⁺) and a polysulfobetaine monomer in an explicit water solvent environment at the atomistic scale. According to the study of the DFT-optimized structure, the hydronium ion and the negatively charged sulfonate group of the betaine unit exhibit strong electrostatic interaction. Significant charge transfer and polarization upon complexation are confirmed by Mulliken charge distribution and bond length studies. The advantageous binding locations for the proton carrier are graphically represented by molecular electrostatic potential (MEP) maps. Additionally, analysis of the HOMO-LUMO orbitals and their energy gap provides insight into the system’s electronic structure stability and reactivity. These findings provide fundamental quantum-chemical evidence that the molecular structure of polysulfobetaine can efficiently coordinate and stabilize hydronium ions, an essential step for promoting proton-hopping (Grotthuss) mechanisms and enhancing membrane performance in general.
REVIEW: OPTICAL PROPERTIES OF SILICON CARBIDE-BASED COMPOSITE MATERIALS
This review provides a comprehensive analysis of the optical properties of silicon carbide (SiC) across various structural forms, from bulk crystals to 0D nanostructures and depending on different parameters and factors. The study systematically evaluates the dependence of SiC's intrinsic optical response on its polytypism, where the indirect band gap is shown to scale with hexagonality from 2.36 eV (3C-SiC) to 3.23 eV (4H-SiC). For thin films and heterostructures, it is observed that processing parameters, such as annealing at 800°C and increasing layer thickness to 250 nm, optimize crystallinity and reduce the absorption coefficient by nearly 20%. At the nanoscale, quantum confinement effects induce a significant blue shift in optical transitions, with band gaps reaching 4.5 eV in 0D quantum dots. The review further details the impact of excitonic binding energies, which reach values of 0.5–1.0 eV in 2D SiC monolayers, highlighting the necessity of GW+BSE many-body corrections for accurate optical modeling over standard DFT methods. Finally, the investigation of SiC nanofluids reveals a 150% enhancement in solar absorption efficiency and 98% long-term durability, confirming SiC as a robust candidate for direct absorption solar collectors. The work concludes by identifying current gaps between theoretical predictions and experimental validation, emphasizing the need for integrated modeling in future SiC-based photonic research.
BIODEGRADABLE GEL-POLYMER ELECTROLYTES FOR SOLID-STATE SUPERCAPACITORS: CURRENT STATUS AND PROSPECTS
Biodegradable gel-polymer electrolytes (GPEs) represent a promising alternative to liquid electrolytes and synthetic separators in solid-state supercapacitors for wearable electronics, biomedical devices, and autonomous sensors. They offer enhanced safety, prevent electrolyte leakage, increase device flexibility, and reduce environmental impact. This review systematizes current approaches to the development of biodegradable GPEs based on chitosan, alginate, gelatin, cellulose and its derivatives, starch, lignin, polylactic acid, and other polymers. Methods of modification (crosslinking, functionalization, compositing, incorporation of nanofillers) and mechanisms of ion transport in gel matrices are considered. Particular attention is paid to the influence of the electrolyte on ionic conductivity, equivalent series resistance (ESR), operating voltage, and cyclic stability. The main limitations of biodegradable GPEs and prospects for the development of “green solid-state energy storage devices are discussed.
ASSESSMENT OF THE EFFECTIVENESS OF INDIVIDUAL DOSIMETRIC CONTROL OF PERSONNEL WORKING WITH ¹³¹I UNDER CONDITIONS OF RADIONUCLIDE THERAPY AND DIAGNOSTICS: ANALYSIS OF REGULATORY LIMITATIONS AND REDUCTION OF OCCUPATIONAL RISKS
This study investigates the characteristics of individual dose formation in Category A personnel (n = 20) working with radioactive iodine-131 (¹³¹I) under conditions of radionuclide therapy and diagnostics. The aim of the study was to assess the informative value of individual dosimetric monitoring for the analysis of both external and internal exposure in the real clinical practice of the Center of Nuclear Medicine and Oncology of the Abai Region. Based on a retrospective analysis of individual dosimetric monitoring data and in vivo spectrometry measurements, the variability of ¹³¹I activity in the thyroid gland of personnel and its contribution to the annual effective dose were evaluated. It was demonstrated that, when radiation safety regulations are complied with, occupational dose levels remain significantly below established regulatory limits. At the same time, differences in internal exposure indicators were found to be more strongly associated with individual clinical and physiological characteristics of thyroid function than with the conditions of professional activity. The obtained results demonstrate that individual dosimetric monitoring can be considered not only a regulatory tool but also an analytical instrument that enables deeper interpretation of dose formation mechanisms and supports the justification of further optimization of radiation protection systems in accordance with the ALARA principle.
STUDY OF THE STRUCTURAL-PHASE STATE OF THE MECHANICALLY ACTIVATED SYSTEM Pd-Ti-Mg
This work examines the structural–phase state and microstructural organization of mechanically activated ternary Pd-Ti-Mg powders as candidate materials for solid-state hydrogen storage. Elemental powders were processed by high-energy planetary milling (Pulverisette 7, 500 rpm; BPR=10:1) in Ar. X-ray diffraction (Cu Kα) reveals fcc-Pd (Fm-3m, a=3.887 Å), α-Ti (hcp, P6₃/mmc, a=2.950 Å, c=4.681 Å), a metastable fcc-Ti fraction (Fm-3m, a=4.060 Å), and minor hcp-Mg (P63/mmc, a=3.209 Å, c=5.211 Å); no distinct intermetallic peaks are resolved at the bulk level. Laser diffraction shows a multimodal size distribution with D10≈5 μm, D50≈20 μm, D90≈50 μm (span≈2.25), a fine sub-5 μm mode, and a coarse 300-600 μm tail attributed to Mg. SEM-EDS mapping evidences a mosaic microstructure: isometric Pd-rich domains (~10-60 μm), platy Ti-rich fragments (~20–80 μm), local Pd-Ti colocalization at interfaces (interpreted as a prereaction state for Pd-Ti intermetallics), and predominantly intergranular, dispersed Mg. The combined data indicate abundant high-energy interfaces and shortened diffusion paths created by mechanical activation, which are favorable for accelerating (de)hydrogenation while avoiding premature formation of bulk intermetallics. The results provide a microstructure-guided route to tune capacity, kinetics, and cycling stability via controlled milling parameters and targeted thermal schedules that promote beneficial Pd↔Ti interfacial reactions while limiting Mg segregation and oxidation.
ADAPTATION OF [¹⁸F]PSMA-1007 RADIOSYNTHESIS TECHNOLOGY AND QUALITY CONTROL IN A CLINICAL CENTER OF THE ABAI REGION
Radiopharmaceuticals based on ligands targeting the prostate-specific membrane antigen (PSMA) are recognized as the “gold standard” for prostate cancer (PCa) imaging using positron emission tomography (PET). This study presents, for the first time in the Republic of Kazakhstan, the results of adapting an automated one-step radiosynthesis technology and performing a comprehensive quality assessment of the [¹⁸F]PSMA-1007 radiopharmaceutical at the Center for Nuclear Medicine and Oncology (Semey, Abai Region). During the study, the direct nucleophilic radiofluorination protocol was optimized, resulting in a stable radiochemical yield (mean 48%) while reducing the total synthesis time to 35–40 minutes. A full quality control cycle confirmed complete compliance of the final product with the European Pharmacopoeia specifications, including radiochemical purity (97–98%), sterility, and apyrogenicity. The successful implementation of this project represents a strategic milestone in the development of nuclear medicine in Kazakhstan. The validated stability and quality parameters of [¹⁸F]PSMA-1007 provide a scientific and methodological basis for scaling up hightechnology production at future cyclotron facilities across the country. The introduction of this radiopharmaceutical into clinical practice significantly improves the accuracy of prostate cancer staging and recurrence detection in Kazakhstan in accordance with international standards.
FORMATION AND PROPERTIES OF CoTiO3 CERAMICS WITH THE INTRODUCTION OF OXIDE STABILIZING ADDITIVES
A comprehensive study was carried out to investigate the influence of the type of cobalt-containing component and stabilizing oxide additives on the phase composition, microstructure, and mechanical properties of cobalt titanate-based ceramics synthesized by mechanochemical solid-state processing. Cobalt nitrate, cobalt sulfate, and cobalt chloride were used as cobalt-containing precursors and mixed with titanium dioxide in equimolar ratios, followed by mechanochemical milling and thermal sintering at 1000 °C. X-ray diffraction and scanning electron microscopy revealed that a two-phase CoTiO3-TiO2 (rutile) system is formed in all samples, while the phase ratio and microstructural features strongly depend on the type of the initial cobalt-containing component. The use of cobalt chloride was shown to increase the weight fraction of the CoTiO3 phase up to ~60 wt.% and to promote the formation of a denser and more homogeneous microstructure compared with ceramics synthesized using cobalt nitrate and cobalt sulfate, in which the rutile phase dominates. It was established that the introduction of stabilizing oxide additives ZrO2 , MgO, and Y2O3 suppresses grain growth and increases the density of interphase boundaries. The addition of yttrium oxide is accompanied by the formation of a secondary Y2Ti2O7 phase and provides the most pronounced structural strengthening effect. The maximum microhardness value (742 ± 14 HV) was achieved for Y2O3-modified samples. The obtained results demonstrate that a targeted selection of the cobalt-containing components and stabilizing oxide additives enables effective control over the phase composition, microstructure, and mechanical properties of CoTiO3-ceramics synthesized by the mechanochemical method.
SUBCRITICALITY ANALYSIS IN SNF CONTAINERS OF THE BN-350 REACTOR
The relevance of this research is associated with the need to analyze subcriticality under all regulated and accidental storage scenarios during the long-term storage of spent nuclear fuel (SNF) from the BN-350 reactor. Although all necessary calculations and studies were performed during the development and design of the storage facility, updated calculations are required to confirm the safe storage of BN-350 SNF as a real and aging facility. The objective of this work was to assess container storage from the standpoint of nuclear safety, ensuring guaranteed subcriticality under certain accident conditions The results of the storage cask system (SCS) containing eight fuel canisters show that when the SCS with SNF is in either mechanically intact or damaged condition, and even when surrounded by a group of SCS units, the effective multiplication factor keff changes insignificantly. However, it begins to increase when water appears in the calculated configurations. The most critical situation occurs when a steam–water mixture forms in the cavities of the container and canisters, which may occur due to degradation of protective barriers
ASSESSMENT OF THE ACTIVITY OF LIQUID RADIOACTIVE WASTE FROM THE BN-350 REACTOR SOLIDIFIED WITH SORBENTS
Assessment of the activity of radioactive waste (RW) stored in the tanks of the BN-350 reactor facility is necessary to ensure safe storage and to support the selection of appropriate waste management technologies. This is one of the key elements of the radiation safety system, ensuring proper classification, safe storage, and subsequent disposal of radioactive materials. Within the framework of this study, the specific activity of liquid radioactive waste (LRW) immobilized using sorbents was evaluated based on gamma radiation for the years 2025, 2050, and 2075. The concentrations of the major long-lived radionuclides were determined for the same periods. The specific mass fraction of fissile materials in the radioactive waste was also calculated. The object of the study is liquid radioactive waste solidified using sorbents such as perlite, agrovermiculite, and superabsorbent. The results may be used to select appropriate sorbents for further radioactive waste management operations.
ASSESSMENT OF RADIATION RISK FROM SURFACE SOIL TO THE POPULATION OF THE KYZYLORDA REGION IN URANIUM MINING AREAS
The results of gamma spectrometric investigations of the radionuclide composition of the surface soil layer in uranium mining areas of the Kyzylorda region (the North and South Karamurun, Irkol, Kharasan-1 and Kharasan-2 deposits), as well as in adjacent settlements and agricultural lands, are presented. Based on the activity concentrations of natural gamma-emitting radionuclides of the uranium and thorium series and potassium, the absorbed gamma dose rate in air at a height of 1 m above ground level, the annual effective dose from external exposure to the population, the external hazard index, and the lifetime cancer risk were calculated. It is shown that, for most of the surveyed sites, the activity concentrations of natural radionuclides and the derived radiological parameters fall within ranges comparable to global average values and the reference levels recommended in UNSCEAR documents and national sanitary regulations. Local increases in radionuclide activities are confined to areas with enhanced uranium mineralization and in zones directly influenced by uranium mining activities.
FEATURES OF PRODUCING THE RADIOPHARMACEUTICAL DRUG “FLUORODEOXYGLUCOSE 18F” USING A LOW-POWER CYCLOTRON: EXPERIENCE AND PERSPECTIVES
The study presents a comparative analysis of pharmacy-based and industrial production of the radiopharmaceutical 2-[¹⁸F]fluoro-2-deoxy-D-glucose (¹⁸F-FDG). The study compares the infrastructure, synthesis process, purification and dispensing systems, as well as quality control procedures, including radionuclidic and radiochemical purity, residual solvents, bacterial endotoxins, pH and sterility. The study demonstrates that small-scale pharmacy production based on a compact cyclotron complex with cassette synthesis modules provides product quality comparable to centralized industrial production on a high-energy cyclotron with an extended analytical infrastructure. The pharmacy model allows implementation of a “dose-on-demand” principle, reducing activity losses and ensuring flexible supply for patients of a specific center. The industrial model provides high throughput and centralized supply for a network of PET centers. The results emphasize that both organizational models are capable of maintaining high quality and safety standards for ¹⁸F-FDG, while the choice of an appropriate production scheme depends on the size of the center, patient flow, and regional logistic conditions.
STUDY OF THE LUMINESCENT CHARACTERISTICS OF PURE AND FLUORINE-CONTAINING BIO-HYDROXYAPATITE
This work presents a comparative study of pure and fluorine-containing hydroxyapatite (HAp and HAp–F), focusing on the effect of fluoride ions on the structural and optical properties of the material. The samples were synthesized using a rapid pyrolysis method and characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and luminescence spectroscopy. XRD analysis showed that both materials crystallize in a hexagonal apatite structure with the space group P6₃/m. The FTIR and XRD data suggest structural changes associated with the partial incorporation of F⁻ ions and modifications in the local environment of phosphate groups. The spectral and luminescence measurements revealed that the presence of fluorine affects the luminescence behavior, including changes in the visible spectral region and possible modification of energy-transfer processes. Overall, these findings show that the incorporation of fluorine influences the structural and optical properties of hydroxyapatite and may provide a basis for further studies of apatitebased materials for biomedical and luminescent applications.
USE OF A PERLITE-BASED INORGANIC SORBENT FOR THE IMMOBILIZATION OF SALTCONTAINING LIQUID RADIOACTIVE WASTE
This study presents a comprehensive investigation of producing solid forms of liquid radioactive waste by selective sorption using perlite as a sorbent. The technological process includes impregnation of perlite with a model salt-containing liquid radioactive waste (LRW), drying to remove excess moisture, pressing with sample formation, and subsequent sintering in a muffle furnace. Sintering was carried out in the temperature range of 300–500 ºC with a holding time of 60 minutes. Microstructural analysis using optical microscopy and scanning electron microscopy revealed a transition from a highly porous structure to a denser and more cohesive microstructure with increasing sintering temperature. As the temperature rises to 400 ºC, material densification becomes clearly evident; however, at higher temperatures, a slight decrease in density is observed. The microhardness of the samples increases throughout the investigated temperature range, indicating strengthening of interparticle bonds and correlating with the microstructural analysis results. The obtained findings confirm the significant role of sintering temperature in the formation of structure and mechanical properties of perlite-based solid forms and demonstrate the potential of the proposed approach for immobilization of salt-containing liquid radioactive waste.
ATOMISTIC-SCALE MODELING OF THE INTERACTION OF A BUTANOIC ACID/THYMOL-BASED DEEP EUTECTIC SOLVENT WITH GLYCEROL
The economic feasibility of biodiesel depends on the proper removal of glycerol, a main byproduct that decreases gasoline quality. Current purification processes can be energy-intensive or produce secondary waste, necessitating the creation of new, efficient solvents. This study uses Density Functional Theory (DFT) at the B3LYP/6-311G++(d,p) level, along with D3(BJ) dispersion correction, to assess a butanoic acid/thymol-based deep eutectic solvent (DES) for glycerol extraction. The glycerol-DES complex underwent quantum-chemical computations, which included geometry optimization, natural population analysis, and frontier orbital characterisation. The examination of contact energies, electrostatic potential maps, and molecular orbitals reveals that the interaction is exothermic (ΔH_int = -20.3 kJ/mol). However, the positive change in Gibbs free energy (+21.9 kJ/mol) and the large negative entropy change (-142.1 J mol⁻¹ K⁻¹) suggest the non-spontaneous character of the interaction at ambient conditions, which is predominantly driven by enthalpy. The findings provide fundamental atomistic-scale insights into the interaction mechanisms, demonstrating the efficacy of DFT for selecting DES candidates. While the exact butanoic acid/thymol combination is theoretically unsuitable for spontaneous glycerol removal, this study provides a strong computational basis.
METROLOGICAL CHARACTERISTICS OF REPEATABILITY AND LABORATORY PRECISION OF THE NEUTRON-ACTIVATION ANALYSIS TECHNIQUE FOR SHORT-LIVED RADIONUCLIDES ON WWR-K
A new certified analytical technique (CAT) for neutron activation analysis (NAA) by short-lived radionuclides is being developed. Sample activation is performed using a pneumatic transport system (with a built-in specialized spectrometric complex) integrated into a dedicated horizontal channel of the WWR-K research nuclear reactor in the Institute of Nuclear Physics (Almaty city). The conditions for collecting experimental data and the algorithms for calculating metrological characteristics were determined in accordance with the requirements of the current regulatory framework and the State System for Ensuring the Uniformity of Measurements of the Republic of Kazakhstan. Calculations of the repeatability and laboratory precision indicators of the CAT were performed for a wide range of concentrations of the elements Al, Cl, Cu, Dy, In, Mn, Ti, and V. The results obtained are intended for preparation for the certification and inclusion of this CAT in the State Register of Measuring Instruments of the Republic of Kazakhstan. The methodology, which currently has no analogues either in the Republic of Kazakhstan or in the post-Soviet space, is intended for use on specific, unique experimental equipment for the study of solid powder samples.
MODELING OF THE THERMAL STATE OF THE CRYSTALLIZER OF AN ELECTROSLAG REMELTING UNIT AFTER THE FORMATION OF THE METAL MELT
The processing and decontamination of metallic radioactive waste is one of the pressing challenges associated with the utilization of nuclear energy. One of the methods used for the treatment and purification of metallic waste is electroslag remelting. This paper discusses the modeling of the thermophysical state of the crystallizer in an electroslag remelting facility using the ANSYS FLUENT software package. A geometric model and a computational model were developed, and calculations of the crystallizer thermophysical behavior were performed under conditions corresponding to previously conducted experimental runs. The simulation results illustrate the thermal behavior of the crystallizer during the cooling of the metallic melt formed within it. The obtained results confirm the physical consistency of the adopted boundary conditions and heat transfer parameters.
SODIUM HANDLING TECHNOLOGIES FOR FAST REACTOR DECOMMISSIONING: A REVIEW
Sodium fast neutron reactors currently demonstrate the highest technological readiness for industrial operation and transition to a closed nuclear fuel cycle. At the same time, the expansion of the fleet of nuclear power plants with fast sodium reactors in the future will inevitably lead to the need to solve the problems of their decommissioning. One of the key challenges of this stage is the management of sodium as a coolant, which is due to its physicochemical properties. These physical and chemical features significantly complicate the processes of dismantling and decontamination of reactor plant equipment. In this regard, the accumulated experience in management of sodium during the decommissioning of experimental demonstration fast sodium reactors is of particular value. Thus, this article provides an overview of current and promising sodium management technologies at the stage of decommissioning sodium fast neutron reactors.
EFFECT OF WET CHEMICAL ETCHING ON IMPURITY REMOVAL AND PHOTOCATALYTIC PERFORMANCE OF METALLURGICAL SILICON POWDER
This study investigates the effect of wet chemical etching on impurity removal and the photocatalytic properties of metallurgical-grade silicon (Si) powder. The Si powder was subjected to a two-stage high-energy ball milling process followed by acid etching using an HF:HCl:HNO3 mixture under controlled conditions. The morphology and composition of the samples were analyzed using transmission electron microscopy (TEM) and energy-dispersive spectroscopy (EDS). The results revealed particle sizes below 200 nm and a well-defined crystalline structure with an interplanar spacing of ~0.20 nm, corresponding to the Si (220) plane. EDS analysis confirmed the effective removal of metallic impurities (K, Ca, Ni) and carbon, while an increase in oxygen (~8 at.%) and nitrogen (~12.2 at.%) content was observed due to surface oxidation and chemical treatment. The photocatalytic activity of etched (Sip) and untreated (Sis) silicon powders was evaluated via the degradation of methylene blue (10 mg/L) under UV irradiation. After 120 minutes, the concentration ratio Ct/C0 decreased to ~0.18 for Sip, compared to ~0.9 for Sis. A more than fourfold reduction in the absorption peak at 664 nm was observed for Sip, indicating enhanced dye degradation. Kinetic analysis showed that the degradation process follows a pseudo-first-order model, with higher rate constants for the etched samples. The improved performance is attributed to impurity removal, reduced charge carrier recombination, and increased active surface sites. These results demonstrate that wet chemical etching is an effective and scalable approach to enhance the functional properties of metallurgical silicon for environmental photocatalytic applications.
DETERMINATION OF THERMAL STABILITY OF SORBENT-BOUND LIQUID RADIOACTIVE WASTE
The paper presents a methodology for determining the thermal stability of the “LRW–sorbent” system, intended to assess the feasibility of converting liquid radioactive waste (LRW) into a non-flowing state using sorbent materials. Natural and synthetic sorbents of different origins were used as study objects, including perlite, perlite sand M-100, vermiculite, agrovermiculite, a synthetic polymer sorbent (“superabsorbent”), and a mineral sorbent developed at Shakarim University. The sorbents were tested for freeze–thaw resistance (50 cycles at ±40 °C) and long-term thermal stability (600 hours at +50 °C). It was found that perlite-based sorbents exhibit the most favorable combination of properties, combining high absorption capacity with resistance to thermal cycling. The mineral sorbent developed at Shakarim University (“S-sorbent”) demonstrated minimal changes in mass and structure; however, its sorption capacity is lower than that of perlite. Vermiculite and agrovermiculite showed mechanical stability but insufficient liquid retention capacity, while the superabsorbent was excluded from further consideration due to structural degradation under thermal exposure. The obtained results confirm the applicability of the proposed methodology for predicting the behavior of “LRW–sorbent” systems under temperature conditions typical for storage. The results may be used to substantiate technologies for the management of LRW from the BN-350 reactor facility.
ASSESSMENT OF THE PROSPECTS FOR THE USE OF CHROMIUM BERILLIDES (CrBe12) AS A MATERIAL FOR STEAM TURBINE BLADES OPERATING IN ULTRA-CRITICAL WATER VAPOR CONDITIONS
This paper evaluates the prospects for using chromium beryllides (CrBe12) as a candidate material for the blades of steam turbines operating under supercritical steam conditions. A diffusion model of oxidation has been developed, taking into account the formation of a Cr2O3-enriched protective layer and its possible degradation due to cracking. It is shown that at a temperature of 600°C, chromium beryllides are characterized by a significantly lower oxide layer growth rate compared to ferritic-martensitic steels and titanium alloys, and a comparable or lower rate compared to nickel superalloys. It is assumed that the low density of CrBe12 leads to a significant reduction in centrifugal stresses. The analysis conducted showed that CrBe12 can be considered a promising candidate material for further research regarding components of nextgeneration steam turbine systems in a temperature range up to 650°C. However, the results obtained should be considered preliminary and require direct verification under ultra-superheated steam conditions, as well as through additional analysis of creep, fatigue, and thermal-cyclic resistance.
SYNTHESIS, STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF THE BIMETALLIC CATALYST PT–RU/C FOR FUEL CELLS
This article presents the synthesis and comprehensive study of a bimetallic Pt-Ru/C catalyst with a Pt content of 5% by weight and a Pt:Ru atomic ratio of 1:1, obtained by chemical reduction on a carbon support. The morphology and structure of the material were studied using scanning and transmission electron microscopy, which revealed the formation of highly dispersed Pt-Ru nanoparticles with a size of about 2-5 nm, uniformly distributed over the surface of the carbon matrix. The elemental composition and homogeneity of the component distribution were confirmed by energy-dispersive spectroscopy. The phase composition of the catalyst was studied by X-ray diffraction, the results of which indicate the formation of a nanocrystalline Pt-Ru structure without obvious phase separation. The structural characteristics of the surface, determined by low-temperature nitrogen adsorption-desorption, showed the presence of a developed mesoporous structure with a high specific surface area and porosity, ensuring efficient mass transfer. The electrochemical properties of the catalyst were evaluated using cyclic voltammetry in a 0.5 M H₂SO₄ solution. The results reveal hydrogen adsorption-desorption peaks, as well as the formation of ruthenium oxide particles, indicating a bifunctional mechanism. The catalyst exhibits high electrochemical activity and stability due to the uniform distribution of the active phase and the developed support surface area. Thus, the resulting Pt–Ru/C catalyst is characterized by optimal structural and electrochemical properties and is an effective material for use in low-temperature fuel cells.
INFLUENCE OF HUMIDITY AND ENVIRONMENTAL CONDITIONS ON THE EFFICIENCY OF PHOTOCATALYTIC AIR PURIFICATION. A BRIEF ANALYSIS
This study analyzes the influence of environmental parameters on the efficiency of photocatalytic processes for air purification. Modern photocatalytic air purification systems utilize light-activated semiconductor materials to generate reactive oxygen species capable of oxidizing pollutants to less toxic products. Experimental data indicate significant progress in the development of photocatalysts based on oxide and heterostructured materials. However, the high activity of photocatalytic materials demonstrated in laboratory conditions is not always reproducible under real-world environmental conditions. The study focused on the influence relative humidity, solar radiation intensity, ambient temperature, and mass transfer conditions on the kinetics of photocatalytic reactions and the availability of active surface sites. It was found that the effect of humidity is nonlinear and is determined by the balance between the formation of hydroxyl radicals and the competing adsorption of water molecules and target pollutants. The efficiency of photocatalytic processes under real-world conditions is determined not only by external environmental parameters but also by the structural design of the systems themselves. Integrated photocatalytic structures, such as fibrous membranes and composite materials, offer the most promise. These structures provide simultaneous filtration, adsorption, and catalytic oxidation of pollutants, as well as improved mass transfer to active sites. This architecture significantly improves the stability and reproducibility of photocatalytic activity under varying environmental conditions. A further evaluation of practical efficiency was conducted, taking into account the formation of reaction intermediates and their potential impact on human health. It was shown that the use of photocatalytic oxidation without preor concomitant filtration can lead to the formation of undesirable byproducts, whereas combined systems provide more thorough air purification and reduce the negative impact on cardiorespiratory parameters. Overall, the obtained results indicate the need to move from a material-based approach to a systems-based design of photocatalytic technologies, taking into account their real-world operating conditions.