Journal Issue: Nuclear Energy and Technology (NUCET)
Загружается...
Volume
10
Number
4
Issue Date
Journal Title
Journal ISSN
2452-3038
Том журнала
Том журнала
Статьи
Публикация
Открытый доступ
Calculations of the principal neutronic characteristics of a hypothetical VVER assembly with minor actinides incorporated into PuO2 -ThO2 fuel in a duplex configuration
(НИЯУ МИФИ, 2024) Kabach, O. ; Radi, A.; Chakir, E. M.
The VVER-1200/AES-2006 is recognized as a leading Gen III+ nuclear reactor design, meeting stringent international safety standards. This study evaluates the use of a novel PuO2 -ThO2 duplex fuel, incorporating weapon-grade plutonium (WgPu) and thorium, for a hypothetical VVER-1200 assembly. The research also explores incorporating minor actinides (MAs) for transmutation, comparing two methods: MAs coated on WgPuO2 and MAs mixed with WgPuO2 as integral fuel burnable absorber rods. Neutronic properties of these fuels are compared to those of LEU-fueled assemblies. The results show a 135% higher burnup for the duplex fuel compared to LEU, with extended criticality, reduced reactivity swings, and lower Pu-239 concentrations upon discharge. While Np-237 and Am-241 concentrations decrease, Am-243, Cm-244, and Cm-245 increase, but overall radiotoxic waste is reduced. Enhanced safety coefficients are also observed, within acceptable LWR ranges.
Публикация
Открытый доступ
On plutonium-241 and americium in the twocomponent nuclear energy system
(НИЯУ МИФИ, 2024) Troyanov, V. M.; Gulevich, A. V.; Gurskaya, O. S. ; Dekusar, V. M.; Eliseev, V. A. ; Moseev, A. L.
The paper deals with the influence of the strategy for using separated plutonium from spent fuel of thermal and fast reactors, as well as homogeneous burning of americium in the BN reactor core on the balance of americium in the Russian nuclear fuel cycle throughout the 21st century. The assessment is carried out with the use of athematical modeling of nuclear materials movement including nuclide transformations throughout the nuclear energy system based on the CYCLE code. Scenario modeling of the americium and Pu-241 accumulation was carried out in Russia’s two-component nuclear energy system model with thermal (VVER) and fast (BN) reactors. In so doing, spent nuclear fuel (SNF) reprocessing was simulated in 2 options: as priority eprocessing of SNF of VVER reactors (1) or SNF of BN reactors (2). In addition to americium accumulation in the system without burning, the accumulation of this actinide was studied taking into account its homogeneous burning in the MOX-fuel of fast reactors at the level of its equilibrium content of ~1%. It has been shown that the priority reprocessing of VVER spent fuel makes it possible to reduce the americium accumulation by the end of the century by ~8 tons, and the effect is achieved by using freshly separated plutonium with short-term cooling, thus, by priority the americium source is eliminated, without directly handling it. Homogeneous addition of americium to the fuel of fast reactors of the BN-1200 type at a level of ~1% makes it possible to stop accumulation of americium in a two-component energy system by 2070, tabilizing it at a level of ~40 tons in the scenario with priority reprocessing of VVER SNF and ~50 tons in the scenario with priority reprocessing of BN SNF.
Публикация
Открытый доступ
Actual problems of modeling thermal-hydraulic processes in fast neutron reactors
(НИЯУ МИФИ, 2024) Kuzina, Yu. A.; Sorokin, A. P.
The results of studies on hydrodynamics and heat transfer processes in fast neutron reactors are presented. Data on turbulent momentum transfer in rod bundles are analyzed. It is shown that the intensification of turbulent momentum transfer in the rod bundle channels is due to large-scale turbulent momentum transfer (secondary currents). The intensification of interchannel turbulent exchange in close-packed lattices of rods is explained. A dependence is obtained for the dissimilarity coefficients of interchannel convective exchange forced by wire wrapping in bundles of rods. The methods and results of numerical modeling of thermal hydraulics using the Monte Carlo method, thermomechanical analysis of the temperature field in fuel rod assemblies in the lifetime process are presented. The results of modeling based on a water model of temperature fields and the structure of coolant movement in the primary circuit of the reactor in various regimes are presented. A stable temperature stratification of the coolant was revealed in the peripheral zone of the upper chamber of the reactor above the side screens. It is shown that the process of boiling liquid metals in fuel assemblies has a complex structure, characterized by stable and pulsating regimes and a heat transfer crisis. The agreement between the results of experimental and numerical modeling is shown. A cartogram of the flow regimes of a two-phase flow of liquid metals in fuel rod assemblies has been plotted. The influence of the surface roughness of fuel elements on the boiling process and heat transfer during boiling of liquid metals is analyzed. Long-term cooling of a fuel assembly with a “sodium cavity” above the reactor core in accident regimes with boiling of liquid metals is shown. The objectives of further research are formulated.
Публикация
Открытый доступ
New technical solutions for the design of NPP passive safety systems
(НИЯУ МИФИ, 2024) Soloviev, S. L.; Zaryugin, D. G.; Kalyakin, S.G.; Leskin, S. T.; Soloviev, D. S.
The paper describes the new principle of passive NPP safety systems designing, in which the natural circulation of working fluid or gas is replaced by forced circulation in order to increase it’s capacity. The energy required by the system is converted from the emergency process itself, which this system resists when performing a given safety function. The goal is to expand the variety and capacity of passive NPP safety systems in order to optimize and reduce costs of NPP power units with various types of reactors while increasing the safety level. The proposed technical solutions are based on the use of direct non-mechanical conversion of the energy, comprised in emergency process, to electricity, and then to mechanical energy of hydraulic machine for working medium moving in a forced circulation mode. To demonstrate the proposed principles, the following technical solutions have been considered:
• new passive electrochemical hydrogen recombiner for NPPs with light water reactors. Application of new techniques allowed increasing the performance by weight of the recommended hydrogen simultaneously with increasing the hydrogen torch threshold, as well as other important characteristics;
• passive emergency core cooling system for heavy liquid metal cooled reactors. Application of new techniques allowed increasing the core remove heat capacity in order to scale down the main equipment;
• passive system for in-vessel core melt retention of Pressurized Water Reactors of high thermal capacity (more than 3000 MWe). Application of new techniques allowed increasing the system thermal capacity in order to be able to apply to high thermal power reactors like VVER-1000 and more.
Публикация
Открытый доступ
Analysis of the excitation function of deuteron induced nuclear reaction on Neon-20 using COMPLET code
(НИЯУ МИФИ, 2024) Degu Belete G ; Asres, Y. H.; Zegeye, S. M.; Alemu, Y. E.
In this study deuteron induced nuclear reaction on 20Ne target was studied to get nuclear information about 18F and 21Na radioisotopes which are widely used in medical and nuclear reactor technologies respectively. This nuclear reaction is important to get nuclear data since the produced radioisotope is widely used in nuclear medicine due to its appropriate short half-life and positron emitter. The main objective of the study was to analyse and interpret the behaviour of the resulting reaction cross section. It also aimed to compare the computed theoretical result with the experimental data retrieved from IAEA EXFOR for its validity. From such nuclear reaction, the reaction cross sections of 20Ne(d, α)18F, 20Ne(d, x)18F, and 20Ne(d, n)21Na reaction channels were computed using a nuclear computational code called COMPLET. The computed reaction cross sections for each channel were found in good agreement with the experimental data within the specified energy range and show a strong correlation as assessed by Pearson’s correlation coefficient. The analysis of the result shows that compound nucleus reaction is found the dominant reaction mechanism at the lower energies of the projectile