Artur Sergeevich Surayev

For the safety assessment of existing reactor systems and the development of advanced nuclear technologies, it is essential to have experimental data on how nuclear fuel and structural materials respond under rapid transient conditions . Pulsed research reactors provide unique capabilities for reproducing short-duration power excursions with high neutron fluxes and rapid energy deposition. Many existing pulsed facilities were commissioned several decades ago and are approaching the limits of their experimental capabilities, highlighting the need for next-generation pulsed reactors. This paper reviews the principal concepts of pulsed research reactors and the physical mechanisms employed to generate intense neutron pulses. The characteristics of IBR-2M, self-quenching solution reactors, TRIGA, TREAT, the BIGR, and the IGR are analyzed to identify their advantages, limitations, and fields of application. The focus is on U-Gr reactors and the historical MIGR concept, which represented an early approach to increasing the performance of graphite pulsed reactors. The proposed large-scale uranium–graphite pulsed reactor is then assessed using preliminary neutronic and thermal results, with an emphasis on experimental channel dimensions, thermal neutron flux, and fluence in the self-quenching pulse and regulated transient modes.

Modern nuclear energy faces the problem of the accumulation, storage, and management of radioactive waste. For radioactive metal waste (RMW), one of the main tasks is to reduce its volume, carry out partial or complete decontamination, and convert it into a compact and stable form that can be safely stored. In this regard, remelting methods are of great interest as they enable volume reduction in radioactive metal waste, redistribute radioactive impurities, and produce a compact metal product that is convenient for further handling. This study presents the development and experimental testing of an electroslag remelting (ESR) facility designed for investigations of RMW processing. The operability of the facility was initially confirmed using a stainless-steel pipe as an RMW simulator. The experiment showed that the developed facility can successfully remelt metal pipes and produce a compact metal product of a required shape, suitable for further handling and storage. Further experiments were performed using real radioactively contaminated 12Cr18Ni10Ti steel pipes from the IVG.1 reactor technological channel. Gamma-spectrometric measurements showed a significant reduction in radionuclide activity in the remelted metal ingots compared with the initial materials. Thus, the obtained results demonstrate the applicability of the developed ESR facility for experimental investigations of RMW processing.

This study investigates the effect of mineral additives of different natures, namely blast-furnace slag, fly ash, and bentonite, on structure formation, phase composition, microstructure, and physicomechanical properties of cement matrices. The analysis included measurements of mass change and linear shrinkage during hardening, determination of density and microhardness, X-ray phase analysis, and microstructural examination by scanning electron microscopy. It was found that the introduction of mineral additives reduced linear shrinkage from 6.06 mm for the control composition to 0.25 mm for the composition with blast-furnace slag, 2.31 mm for the composition with fly ash, and 1.01 mm for the composition with bentonite. The maximum density and microhardness values were obtained for the matrix with blast-furnace slag and amounted to 1.99 ± 0.03 g/cm³ and 39.95 ± 1.12 HV1, respectively, whereas the overall range of values for the investigated compositions was 1.52–1.99 g/cm³ and 30.2–39.95 HV1. X-ray phase analysis showed that the amorphous component varied from 61 to 78%, reaching its maximum value in the composition with blast-furnace slag, which is associated with the formation of poorly crystalline C–S–H and aluminosilicate phases. According to the SEM data, the average size of visible pore-like defects was 2.4 μm for the control composition, 1.4 μm for the composition with blast-furnace slag, 1.3 μm for the composition with fly ash, and 1.7 μm for the composition with bentonite. The most favorable combination of high density, microhardness, developed amorphous component, and homogeneous microstructure was established for the composition with blast-furnace slag. The obtained results can be used as a materials-science basis for the development of cement matrices intended for further studies on the immobilization of solid radioactive waste.

This study presents the radiological characterization of 15 solid radioactive waste samples originating from the BN-350 sodium-cooled fast reactor (Kazakhstan) during its decommissioning phase. The studied materials include components of ventilation and wastewater treatment systems, pipeline elements and various operational tools. The objective of the study was to determine the activity levels of the samples and to assess appropriate pathways for their subsequent management and processing. The results indicate that all studied materials fall within the category of low-level radioactive waste. Gamma spectrometric analysis shows that Cs-137 is the dominant and only identified gamma-emitting radionuclide contributing to the activity of the studied samples.

One of the major challenges facing modern nuclear power engineering is the management of radioactive waste, particularly its accumulation and disposal. This article presents an experimental electroslag remelting facility developed for processing radioactively contaminated metals and alloys. In addition, the results of preliminary experiments on the remelting of radioactively contaminated 12X18H10T stainless steel pipes are presented. These pipes were previously used in the technological channels of the IVG.1 research reactor. The results show that electroslag remelting leads to a redistribution of gamma‐emitting radionuclides between the metallic and slag phases, resulting in a decrease in their specific activity in the steel. However, the obtained steel does not meet clearance criteria for unrestricted use due to residual Co‐60 activity. Nevertheless, electroslag remelting has been shown to be a promising method for decontamination of radioactively contaminated steel, with further improvement possible through optimization of process parameters.

The nuclear power industry preferably aims to a closed nuclear fuel cycle and a transition to a two‐component structure based on the joint operation of thermal and fast neutron reactors. This approach makes it possible to significantly reduce the volume of radioactive waste and increase the efficiency of using uranium fuel. Sodium fast neutron reactors currently demonstrate the highest technical readiness for commercial operation. This status has been achieved through the accumulation of operational experience from research reactors to pilot demonstration projects. Many of these reactors are currently in the process of decommissioning. Decommissioning of sodium fast neutron reactor facilities is associated with serious intellectual, material, and technological difficulties. There is still no overall experience in the world of completing the decommissioning of such facilities. Nevertheless, it is believed that the experience and competencies accumulated in these activities are key to forming a strategy for decommissioning of the future nuclear power plants with fast neutron reactors as an important final stage of the life cycle of such nuclear facilities. This is very important because decommissioning is a complex process that requires careful planning and coordination to ensure the safety of personnel, the public, and the environment in the future. In this regard, this review is devoted to an overview of the current progress in decommissioning various experimental sodium fast neutron reactor facilities. The accumulated experience, existing problems, and prospects for further work have been analyzed.

Реактор ВВЭР (водо-водяной энергетический реактор) относится к типу PWR (реактор с водой под давлением), который широко применяется в мировой атомной энергетике благодаря своей надежности и высоким эксплуатационным характеристикам. В данном исследовании используется компьютерный код MCNP6 для разработки нейтронно-физической модели активной зоны реактора ВВЭР-1000 и проведения расчётов. Основной задачей исследования является воспроизведение ключевых характеристик реактора с высокой степенью точности. Проведены расчеты коэффициента размножения нейтронов и процесса выгорания топлива в активной зоне реактора. Особое внимание уделено расчетам выгорания с учетом реального профиля мощности во время первого топливного цикла. На основе расчетов определены изменения атомной концентрации 235U и 238U в различных зонах активной области. Также исследована динамика концентрации изотопов плутония, ксенона и самария для топливной сборки, что дает возможность оценить их влияние на нейтронно-физические характеристики реактора. Выполнено сравнение полученных результатов с расчетными и экспериментальными данными из литературных источников, что подтверждает их достоверность.

The BN-350 is the first industrial fast neutron reactor in the history of nuclear energy. It is currently undergoing decommissioning. One of the key challenges of decommissioning is managing the solid radioactive waste that has accumulated throughout the reactor’s operational life. At the moment, the accumulated solid radioactive waste is stored in a storage facility within the BN-350 reactor complex. An analysis showed that more than ~7262 tons with 5.17 × 10¹⁴ Bq activity of various types of solid radioactive waste have been accumulated over the reactor operation. They are mainly represented by materials with low activity. At the same time, the main share of activity is comprised of highly active waste with a total mass of ~170 tons and an activity of 4.73 × 10¹⁴ Bq. A solid radioactive waste management strategy has been developed. It includes all stages from collection and classification to transportation and long-term storage. Modern technologies now offer new possibilities. Some radioactive waste can be processed and reused in other economic sectors. In particular, recycling metals and alloys can reduce the volume of solid radioactive waste. It can also return valuable materials to industrial use.