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Abstract: The present paper considers thermal-hydraulic tests of an emergency cooldown system for the BN-800 reactor with forced circulation of sodium in the primary and secondary circuits. The operating range of changes in the flow rate of coolants in the system under various operating modes is determined. Heat transfer in the air heat exchangers of BN-600 and BN-800 reactors is examined. The established Nusselt number dependence is in satisfactory agreement with the RD 24.035.05-89 methodological guidelines. A simple relationship has been obtained using the results of tests and calculations for assessing the capacity of air heat exchangers. The possibility of increasing their capacity by 26% compared to the design value is demonstrated. The significance of the thermosiphon effect on the temperature state of fittings in the emergency cooldown system is demonstrated. The experimental models have revealed the effect of pipeline inclination on the intensity of heat transfer. PubDate: 2025-03-03
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Abstract: The paper considers the developed calculation model of the IGR reactor with an upper cover and concrete biological protection. We have simulated photon transport using the MCNP5 code and the ENDF/B‑5, 6 constant libraries. IAEA and JAEA nuclear data libraries were used to describe the characteristics of fission products, as well as the processes of uranium-235 decay and gamma-ray field formation. The proposed approach can be used to spatially visualize the operating conditions of a nuclear reactor after startups. We have assessed the field and rate of the effective dose in the central hall of the IGR reactor during its operation at a constant power of 100 MW for 40 s. The effective dose rate was determined to estimate potential radiation load on small-sized neutron detectors (fission chambers). These detectors are supposed to measure local values of fast neutron flux density during irradiation of devices in the reactor. We have validated the proposed method for calculating the effective dose of gamma radiation using the results of direct measurements in the central reactor hall. Validation results confirm the correctness of the proposed calculation models and methods, as well as the admissibility of their use for assessing the radiation situation in the central hall of the IGR reactor. PubDate: 2025-03-03
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Abstract: The present paper considers the RASNAR-GAZ validation of the computational model for the steam generator. The model is designed to calculate non-stationary modes of gas-cooled nuclear power plants. For this purpose, experimental data of the THTR-300 reactor were used. The performed validation proved the RASNAR-GAZ software to describe the main parameters of heat and mass transfer between helium and water in a steam generator with accuracy sufficient for engineering calculations of both static and dynamic modes. PubDate: 2025-02-11
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Abstract: The article discusses issues of state safety regulation, as well as policy and practice of handling accumulated and generated radioactive waste in the Republic of Kazakhstan. Approaches to waste classification from the perspective of economic factors are described. The best practices and general approaches used in various countries to search for long-term and reliable solutions of radioactive waste management are considered. PubDate: 2025-02-10
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Abstract: The leading design organizations of the Russian nuclear industry develop nuclear power facilities to satisfy almost any segment of the energy market. Within the framework of the Proryv project direction, a new technological platform for nuclear power is being created based on nuclear power plants with high-capacity reactors and a closed nuclear fuel cycle. Demand for fast reactors in the Russian Federation was thoroughly justified in the 2018 Strategy for the Development of Nuclear Power in the Russian Federation until 2050 and Prospects for the Period until 2100, as well as its updated 2022 version. It should be noted that the role of fast reactors in the energy system may vary depending on the goals and objectives set in terms of the fuel supply and adopted approach to spent fuel and waste management. The article examines various prerequisites that influence the parameters of fast reactors, taking into account these factors in the context of strategic planning along with the latest computational and analytical studies. PubDate: 2025-02-04
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Abstract: The paper considers temperature and humidity simulation of the primary circuit pipeline rooms located at power units No. 3 and 4 of the Kola NPP upon the occurrence of equipment leakage. Simulation results were used to describe the dependence of the leakage on the temperature and relative humidity recorded by the sensors. Thus, advanced methods of automated coolant leak detection were developed; existing methods were adjusted. PubDate: 2025-01-28
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Abstract: The paper provides an analytical expression to determine the optimal rotor length of a gas centrifuge. The optimum is defined as the maximum separation power per unit volume occupied by the centrifuge. Long centrifuge rotors, typical for European centrifuges, appear economically inappropriate. PubDate: 2025-01-27
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Abstract: The paper presents the results of simulating circulation of a lead-bismuth coolant in a hydraulic circuit using the CONV‑3D code. The temperature head and flow rate of the coolant are simulated for various heating power values. The developed code satisfactorily simulates the natural convective flow of a lead-bismuth coolant in a hydraulic circuit, thus being appropriate for analyzing these flow types in various applications. PubDate: 2025-01-27
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Abstract: In the course of the study, various designs of experimental fuel rods with mixed uranium-plutonium nitride fuel and claddings made of various materials were tested as part of the dismountable irradiation devices of the BOR-60 reactor. The experimental fuel rods represent the mock-ups of the BREST-OD-300 and BN-1200 reactor fuel rods, which differ from the real ones in their shorter length, smaller gas collector volume, and fuel column height. Reactor tests and post-reactor studies of 2020–2023 provided new data on the state of fuel, various types of fuel rod claddings, and fuel assembly design elements. PubDate: 2025-01-23
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Abstract: The paper presents a local system for purifying gas flows from volatile compounds of cesium and iodine released during high-temperature operations of spent nuclear fuel reprocessing. The system consists of two universal cartridge gas purification units. The performed study include data on the efficiency of capturing cesium oxide and molecular iodine by ceramic highly porous block-cell contact elements with an aluminosilicate and silver nitrate active layers, respectively. Recommendations for further conditioning of spent cartridges are provided. PubDate: 2024-11-01
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Abstract: The paper considers the issues of processing spent alkaline liquid metal coolant of BN reactors. Methods used in the BR-10 research reactor for processing coolant and its residues are described in detail. The main parameters of solidified products including mechanical strength and cesium-137 leaching rate are provided. The obtained data are compared with the indicators of cement compounds immobilizing an alkaline solution obtained by dissolving radioactive sodium in 10% alkali. The efficiency of purifying high-salt concentrates of liquid radioactive waste generated during reactor decommissioning is provided for three options of modified clinoptilolite. An approach to processing liquid radioactive waste concentrates is briefly described. The current state of the BN-350 reactor is considered indicating the need for processing accumulated radioactive waste for further decommissioning. PubDate: 2024-11-01
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Abstract: The fire protection system of sodium equipment rooms ensures fire safety of fast neutron reactors by localizing and reducing the consequences of leaks and combustion of sodium during depressurization of equipment or pipelines of sodium systems. The present article describes the composition and operation of the fire protection system used at the BN-350 reactor plant. The efficiency of various subsystems and equipment of the fire protection system is considered as applied to the localization of sodium leaks occurred during the operation of the reactor plant. The performed experiments demonstrate the efficiency of drain fire extinguishing as the element of the fire protection system; requirements for drain fire extinguishing subsystems are provided. The article additionally presents data on the most significant sodium coolant leaks during the operation of the BN-350 reactor and considers trends in the development of fire protection systems for sodium equipment rooms of BN reactors. Technical solutions implemented in fire protection systems for the sodium coolant rooms of BN-600 and BN-800 next-generation reactors are examined based on the experience of using fire protection system elements. PubDate: 2024-11-01
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Abstract: Numerical simulation based on contemporary computational codes represents a current trend for the safety justification of existing and planned nuclear power facilities including reactor plants with liquid metal coolants. The present study considers neutron codes developed by IBRAE RAN under the Proryv project direction. The paper discusses CORNER and ODETTA codes based on the discrete ordinate method, the BPSD code for isotope kinetics, activity and decay heat calculation, EVKLID/V1 and EVKLID/V2 integral codes, as well as the COMPLEX software system for substantiating nuclear and radiation safety. PubDate: 2024-11-01
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Abstract: When selecting processes for modernizing existing or newly created radiochemical plants, technologists and developers face many challenges, including issues of economic efficiency. Mathematical simulation represents the best way to optimize process solutions using various criteria. As a tool for solving such problems, we propose to use the VIZART software package implementing the end-to-end optimization calculation of closed nuclear fuel cycle processes, including the optimal ratio for radioactive waste of different activity levels. Using this module, we have analyzed the main components of costs for post-reactor handling of spent nuclear fuel. The minimum cost of handling high-level radioactive waste was calculated for several scenarios of a closed nuclear fuel cycle. The conducted comparative analysis of radioactive waste conditioning technologies considered various types of spent nuclear fuel reprocessing in the modules of pilot demonstration and industrial energy complexes. PubDate: 2024-11-01
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Abstract: The paper describes experimental studies assessing the release of radionuclides into the gas phase from aqueous process media. These include simulators of solutions after clarification and dissolution of spent nuclear fuel (SNF) and re-extraction of transplutonium and rare earth elements. We propose algorithms for calculating the release of elements and its rate during the transition to the gas phase from simulant solutions. The dependence of the radionuclide release rate on the temperature, air flow, and composition of the process medium is shown. In terms of specific activity, strontium, cesium, cerium, ruthenium, europium, and technetium make the greatest contribution to the activity of the gas phase. PubDate: 2024-11-01
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Abstract: The paper considers the development of an innovative lead coolant sampling device for the BREST-OD-300 pilot demonstration fast neutron reactor developed in the Russian Federation within the framework of the Generation IV international initiative. The sampler is equipped with a lateral inclined channel located above the level of the lead coolant and a curved section for sampling both at an operating reactor and in a shutdown mode. The sampler design is protected by two patents of the Russian Federation. The results of tests on loading/unloading a capillary transport tube into a curved sampling channel and the reverse operation are considered. Moreover, the paper presents the results of tests on filling a sampling capsule with a lead coolant sample and its holding during removal from the reactor. The software of the sampler control system was tested for automatic sampling. The performance of the designed sampler is additionally confirmed by thermal engineering, strength, and radiation calculations. PubDate: 2024-11-01
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Abstract: The paper considers the issue of ensuring the reliability and nuclear safety of unique rotary equipment represented with the mobile neutron reflector of the IBR-2M research reactor. The specifics of its operation under the conditions of inaccessibility for visual control and maintenance dictates the need to use indirect methods of monitoring and diagnostics. The performed study demonstrates the efficiency of combined vibration monitoring and diagnostics for detecting operational defects of the PO-3 mobile reflector. Both conventional spectral and non-standard probabilistic methods of vibration analysis are used, including the S-discriminant analysis adapted to the reference state of equipment. The gamma-spectral analysis of radioactive impurities in the reflector lubricant oil significantly increases the reliability of recognizing the technical state of complex machinery. The example of the PO-2R mobile reflector demonstrates the applicability of the neutron activation method to identify the release of metal microparticles in the oil lubricant due to the degradation processes of exhausted equipment. PubDate: 2024-11-01
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Abstract: The present paper considers the simulated distribution of tritium in the primary circuit of an NPP with a VVER reactor and its auxiliary systems. The activity of tritium in the coolant and auxiliary reactor systems varies during power operation, passing through a maximum. The results of calculations for different flow rates of uncontrolled leakage and drain waters are compared with experimental data on tritium activity in the systems of operating VVER NPPs. Calculation results satisfactorily agree with more than 300 points of experimental data, given the value spread of approximately two orders of magnitude. The study assesses the tritium activity of the spray pond and compare calculated tritium emissions with measurement results. As in the case of the primary circuit, calculations are satisfactorily consistent with experimental data. Thus, the calculation method predicts reliable values of tritium activity in liquid media of VVER reactor units. PubDate: 2024-11-01
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Abstract: Conventional economic assessments of nuclear power plant projects include a standard set of design technical and economic characteristics using established methods of economic and investment analysis. Evaluating innovative projects of small modular reactors (SMRs) should account for additional factors related to the specifics of projects, their purpose and territorial location, features of operating modes, optimal project capacity for a specific scenario, etc. Additional factors make project economic estimates more realistic. The article examines critical aspects and factors capable of affecting the economic performance of SMR projects operating in different market niches. Moreover, the article touches upon issues related to the risks of implementing these projects. SMR projects are implemented under external conditions complementing the technical and economic assessments of power plant projects. These conditions include scenario factors, site conditions, regulatory aspects, design requirements, as well as organizational, financial, and market mechanisms. The concept of extended analysis in performing economic assessments of innovative SMR projects is urgent due to their various practical applications. PubDate: 2024-11-01
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Abstract: The paper discusses requirements for the development of the Russian energy complex and electric power industry during the transition to accelerated scenarios for the growth of the country’s economy. We have simulated macroeconomic scenarios and determined energy needs of the domestic market and effective export of fuel and energy, as well as the necessary volume and structure of energy resource production. Difficulties in reconciling the objectives of intensive growth and deep decarbonization of the economy are noted. The scenario-optimized structure of electricity production and installed capacity of power plants is presented. The study demonstrates the expediency of increasing the role of nuclear power plants (NPPs) in the electric power industry. Key requirements for the pace and cost of commissioning new NPPs have been identified. The importance of technological learning effects for enhancing the competitiveness of NPPs in the changing national energy system is noted. PubDate: 2024-11-01