High-temperature gas-cooled reactors (HTGR) are a new type of environmentally clean source of nuclear energy. Their unique properties – capability of generating heat at temperatures to 1000°C and a high safety security – determine the wide possibilities for using reactors of this type to produce hydrogen from water, supply heat for technological processes in different industries, and produce electricity

The OKBM Afrikantov infrastructure created for performing probabilistic safety analysis of nuclear installations used for different purposes is briefly described. The research in which the enterprise participated is presented. Included are the Voronezh nuclear plant with an AST-500 reactor for supplying heat, commercial uranium-graphite reactors ADE-2, -4, -5, a reactor installation with a high-temperature

Information on the key stages in the origination and operation of commercial uranium-graphite and heavy-water reactors is presented. The problems solved for purposes of safety enhancement and lifetime extension of dual-purpose reactors are described and the basic approaches to decommissioning are presented. Information on the specifics of heavy-water commercial reactors is represented.

OKBM Afrikantov has been developing power installations for the icebreaker fleet for more than 60 years. The first generation of reactor installations is represented by the OK-150 loop-type installation for the icebreaker Lenin. At the exhaustion of its operating life it was replaced by the second-generation OK-900 installation. The next stage of the origination of reactor installations for civilian

The use of nuclear energy on submarines has made autonomous and independent navigation possible for long periods of time. OKBM Afrikantov – one of the leading enterprises of the Rosatom State Corporation – has been supplying Russia’s naval ships with nuclear reactor installations for more than 65 years commencing with the development of equipment for the installations on first-generation submarines

The main stages of the origination (in our country) of the world’s first floating nuclear thermal power plant based on the floating power-generating unit Akademik Lomonosov with two icebreaker-type reactor installations whose chief designer and complete supplier is OKBM Afrikantov are presented. The operational model, the motivation for choosing the technical decisions, a brief description of the design

The experience of origination and operation of BN-600, -800 and development of BN-1200 commercial power units of two-component nuclear energy are recounted. Substantiation is given for the engineering solutions allowing efficient production of electricity and closure of the nuclear fuel cycle with sodium-cooled fast reactors.

Tritium emissions from NPP with VVER were estimated based on radiation and technical survey data. It is shown that the population in the NPP-VVER observation zone consumes a significant amount of imported food products, so that equality is not reached between the specific activity of tritium in the water of human tissues and atmospheric water. Taking this into account, an evidenced model is developed

The heat effect of passive catalytic hydrogen recombiners on the AES-2006 sealed containment is examined. It is shown by computational means that the maximum temperature of the containment near the re-combiners is exceeded locally in regimes characteristic for accidents and without adoption of measures to limit the heat flow onto the containment. Methods are proposed for lowering the containment temperature

The particulars of the adaptation of the CONV-3D module for modeling turbulent flows in reactors in the LES approximation are presented. The results of modeling coolant flow in a round tube with Reynolds number 4·103–5·105 in comparison with the Blasius formula are presented. It is shown that the adapted module gives numerical results that coincide with the analytical estimates and DNS calculations

When twisted into a cable, reduced, and wrapped, Nb3Sn composite superconductors are subject to significant deformation and can sustain damage that will affect their electrophysical properties. This article examines the effect of artificially induced surface damage on the electrophysical characteristics and microstructure of 0.82 and 0.7 mm in diameter Nb3Sn superconductors fabricated by the bronze

This work is devoted to hydrogen safety security during severe accidents at NPP as well as the validation of equipment performance of passive safety systems under these conditions. The results of an experimental investigation of the performance of the primary means of measurement module of the hydrogen concentration control system under physicochemical actions on them due to the precipitation of insoluble

The results of laboratory experiments on the sorption separation of uranium and rare-earth elements from nitrate-phosphate solutions on a solid extractant with an active phase in the composition of the heter-oradical phosphine oxide and di-(2-ethylhexyl)phosphoric acid are reported. This extractant was used to attain high capacity and degree of extraction of uranium from solutions with initial uranium

Numerical studies are performed of the separation of a model multi-component isotopic mixture in a three-stream cascade. The particulars of isotope accumulation as a function of cascade shape (length, stage distribution of interstage flow) are examined. The regularities of the effect of the cascade shape on the component concentration in the cascade holdup are determined. An enriched isotopic mixture

The nonproliferation of nuclear materials is the key issue in supplying nuclear fuel to foreign countries. This article discusses the use of regenerated uranium to enhance the security of exports of fresh fuel for light-water reactors. It is shown that if the removal of fuel and its replacement with, for example, natural uranium go undetected, the criminals have long periods of time available to obtain

The results of an analysis of the status and prospects for the development of software used in technical and economic modeling of nuclear-energy systems in systems-analytical and predictive studies of the validation of the prospects for nuclear energy are reported. A classification of the deployed software is given and the IT-particulars of such software are discussed. Actual problems and promising

The results of modeling of incompressible fluid flows in fuel rod bundles performed using the CONV-3D code are reported. The modeling results obtained for different Reynolds numbers and distances between the fuel rods in comparison with experiment are presented. It is shown that the developed code satisfactorily models the flow of an incompressible fluid in fuel rod bundles and can be used to analyze

Two successive stages of the control of a beyond-design basis accident with de-energization of an RBMK reactor together with multiple equipment failures are analyzed: depressurization of the circulation loop and restoration of reactor cooldown with cold water as the reactor subsequently warms up. The factors affecting the pressure surge in the circulation loop on restoration of reactor cooling as the

The design and characteristics of position sensitive detectors implemented in the form of a matrix of individual detectors (modules) with selective registration of electrons and protons are examined. It is proposed that such detectors be used as a basis for considering the possibility of building introscopes with a coded aperture for detecting images of sources of mixed fast-neutron and γ-radiation

The results of calculations of the equilibrium isotopic composition of molten-salt fuel in an experimental channel of the MBIR reactor are presented. Two organizational variants of the fuel cycle for a molten-salt test loop are examined: with extraction of protactinium and without extraction of heavy nuclei. The results show that the maximum thermal power of the test loop channel can reach 12 MW. Reprocessing

Gas-filled neutron tubes generating pulses with specified parameters are needed for neutron well-logging. These parameters are affected most by the ion-pulse shape. The results of numerical modeling of the dynamics of the electron beam, secondary ions, and electrons generated in the volume of the Penning ion source with an electron emitter and their effect on the ion-pulse parameters are examined.

The development of nuclear power plants in the Unified Energy System (UES) of Russia in the period to 2050 under changing conditions of interfuel competition with thermal and renewable energetics is examined. The main external uncertainty factors affecting NPP competitiveness are identified and their ranges are determined. The technological factors of making NPP more competitive by improving their

The experience gained in validating calculations of the ground-surface concentration of a pollutant injected into an urban environment from a stationary high-altitude source is presented. A Gaussian model using the average annual emission, the characteristic parameters of the source, and a real annual wind rose, as well as a Lagrangian-type model, in which the input parameters were the average daily

The results of the application of the similarity theory of thermophysical processes to the modeling of hydrodynamics and heat transfer in liquid metals in intricately shaped channels and rod systems (reactor cores) as well as the temperature and velocity fields in the top chamber of a fast reactor in different operating regimes are reported. Direct modeling can be used without restrictions only for

A method of optimizing the parameters of a three-stream square cascade for separation of multicomponent mixtures of stable isotopes under specified external conditions is proposed. It is based on a combination of a check calculation of the parameters of the cascade based on the separation factor approximation and a numerical search for the values of the external flows which are required to secure a

It is shown that on creation of capital reserve to cover the risk of hypothetical severe accidents in NPP the size of the allocation is comparable to or greater than the fuel costs for a power-generating unit of a large NPP. The damage consequent to severe accidents in NPP is 1000 times greater than the insurance limits adopted for nuclear risks. An empirical power-law function (with exponent 1.6)

The activation of a neutron generator is modeled for two operating scenarios: continuous for 16 h and 100 h at 4 h/day for one month. The distribution of the equivalent γ-ray dose rate was calculated for different times after the generator was shut down. Different grades of steel were considered for the material of the neutron generator flange. The time dependence of the γ-ray dose rate was calculated

Issues concerning fuel cycle closure are discussed. It is shown that from the standpoint of full utilization of reprocessed nuclear materials the main problems are associated with repeated recycling of uranium, the reason being that limitations are imposed on the content of the isotope 232U in fresh fuel produced from reprocessed materials. The losses of the isotope 235U on repeated recycling of reprocessed

A prognosis is made of the radiation impact of planned atmospheric emissions and liquid discharges from NPP with VVER-1200 on native ecosystems. The ERICA assessment tool was used to assess the dose loads for ICRP-recommended representative organisms. The expected irradiation dose from NPP for representatives of the biota is compared with the dose from the existing irradiation, evaluated on the basis

A computational experiment was performed to purify reprocessed uranium hexafluoride from 232,234,236U in an additional product flow of cascades with a specified number of gas centrifuges in stages. The method used in the calculations takes into account the dependence of the separation coefficients of gas centrifuges on their feed flow and flow division factor. A cascade scheme for purification with

Methods of determining the efficiency of the system that controls the seal-tightness of fuel-rod cladding and localizes FA with leaky fuel rods in a fast reactor are examined. It is shown that the design procedure has significant limitations. A procedure for numerical modeling of the transport of delayed-neutron precursors was developed to take account of the special features of liquid-metal coolant

Groups of materials are compared according to their possible use for fuel-pin cladding in the development of accident-tolerant fuel (ATF). Ferritic, ferritic-martensitic, and austenitic steels and chromium-nickel alloys are studied. Currently, only the chromium-nickel alloy 42KhNM can be used in VVER under normal operating conditions as cladding material for ATF. Pre-reactor and reactor studies are

Sixty years of experience in mastering alkaline liquid metals jointly with industry institutes, the Academy of Sciences, and engineering design agencies developing Nuclear Power Facilities (NPF) has culminated in the development of the scientific foundations for their use in nuclear power and the scientific substantiation of the hydraulic parameters and highly efficient technological processes ensuring

The results of studies on the physical chemistry, mass transfer, and technology of alkali liquid-metal coolant are reported. The state of the coolant is determined by the interaction coolant-impurities-structural materials- protective gas. The impurity sources and their intensity were determined: sodium and sodium-potassium alloy – oxygen, hydrogen (tritium), carbon, products of corrosion of structural

Safety enhancement of NPP power units with water-moderated and -cooled reactors on the basis of installation of additional multifunctional low-power steam-turbine generators is studied. It is shown that the parameters of the primary and secondary loops change as the VVER-1000 reactor is cooled via the use of the residual heat in the core to generate steam that serves as the working body for a low-power

To the article “Excitation Functions of the Reactions Ag109 (p, n); Ag109(d, 2n); Ag107 (α, 2n+pn), and Yield of Cd109,” by P. P. Dmitriev, I. O. Konstantinov, and N. N. Krasnov, Vol. 22, No. 4, pp. 386–388, April, 1967.

Methods of calculating the nuclear reactor reactivity from the measured time-dependence of the neutron flux are discussed. It is noted that the corresponding problems for the direct and inverse equations of point kinetics in the approximation of a prompt-jump change of neutron flux are not equivalent, which is expressed in that the reactivity values in these problems do not coincide with one another

The saturation yield of the rhenium radioisotopes 186Re, 188Re, and 189Re on irradiation of a 186W target by the nuclei 4He, 3He, 1H, and 2H with energy 47, 25, 15.3, and 19 MeV, respectively, was measured by the activation method. The chosen energy of the accelerated particles made it possible to minimize the contribution of the activity of long-lived rhenium radioisotopes in the desired radionuclides

The hydraulic resistance of irregular fi ne packing is studied as a function of the process parameters for the rectification of metal hexafluorides. It is shown that the dependence of the hydraulic resistance of irregular fi ne packing on the rectification parameters coincides with the dependence presented in the literature but with different coefficients and exponential factors.

A quantitative assessment of the 131I activity in RBMK coolant as a function of the number of defective fuel pins and the distribution over a fuel run is presented. The 131I yield fraction is determined using a model based on the solution of the diffusion equation with empirical coefficients. This investigation was performed for a core-average FA whose power is a function of the burnup. It is shown

The design of a KGK-2 γ-ray dose rate detector is described. The basic characteristics of the detector are presented. The readings of a KGK-2 gas-filled ionization chamber detector and VED-2 secondary-electron emission detector during power startup of BR-K1 and BR-1M reactors are compared. It is shown that by using KGK-2 and VED-2 detectors in combination the γ-ray dose rate can be measured in the

The purpose of the present work is to analyze the long-term yearly average volumetric activity in the surface air and the yearly absorbed dose of β- and γ-radiation in the spread zone of continuous emissions from NPP. The particulars of the spreading of the emission radionuclides and the associated yearly absorbed radiation dose are determined. It is shown that the atmospheric volumetric activity of

A stand for inspecting experimental fuel pins in the cooling pool of the MIR.M1 reactor and methodological approaches to measuring the height and diameter of experimental fuel pins are described. The basic characteristics of the equipment used for performing measurements are described. The structural features of an experimental FA (EFA) and the test parameters of experimental fuel pins in an assembly

The basic regularities in the transmutation Np, Am, and Cm in a molten-salt burner reactor are examined on the basis of the results of neutronic calculations of an idealized infinite homogeneous medium consisting of metal halogenides with low atomic mass. It is shown that an optimal equilibrium regime for the transmutation of Np, Am, and Cm in a molten-salt burner reactor could exist. In this regime

Grid designs with mixing elements for VVER FA and experimental studies of their thermohydraulic and mass transfer characteristics are analyzed. The Novosibirsk Chemical Concentrates Plant and the Machine Building Plant manufacture the grids. Comparative assessments of the coolant mixing intensity, increase of the critical heat flux and critical power, and coefficient of hydraulic resistance are made

The observed differences of the neutron fluxes between experiments and calculations on passage of neutrons through thick layers of iron and steel are conditioning the use of better models for representing the scattering cross-sections and energy-angle distributions of neutrons in elastic and inelastic scattering. The effect of the NJOY99 and GRUCON prepared nuclear data for Fe, Cr, and Ni on Keff and

The behavior of radionuclides (Kr and Xe) and process gases (CO) in the vacuum-cesium channel of a thermionic converter reactor is modeled by solving Boltzmann’s equation numerically. Modeling techniques and a software system were developed in the course of this work. Series of calculations were performed for the variation of the initial flux of radionuclides, the dependence of the radionuclide flux

A method of calculating and optimizing a multi-flow cascade with a specified number of gas centrifuges in stages on cuts of their partial flows were developed. A special feature of the method is an iterative fitting of the separation coefficients of the gas centrifuges that depend on the feed flow and the division factor of the flow. A computational experiment was conducted on the separation of molybdenum

This article is devoted to model calculations of a lead-cooled reactor core performed using the EVKLID/V1 code. The ingress of water vapor into the core is modeled for the stationary state of the reactor at the rated power capacity. The change in the reactivity and power at different mass flow of water vapor is analyzed. Baseline calculations performed using the MCU-FR code were performed in order

The results of research on the influence of the chemical composition, cold-deformation, and irradiation temperature on the short-time mechanical properties of the austenitic stainless steels 08Kh18N10T, EI-847, EP-172, and ChS-68 after neutron irradiation in the BN-350 fast reactor to damaging dose 57–59 dpa in the range 400–490°C are reported. The investigation showed that high-temperature radiation

EdF’s idea of irradiating in Russian fast reactors fuel pins with recycled plutonium arose in February 2016 during a discussion with CEA of testing experimental FA in BN-600. EdF proposed to additionally irradiated several fuel pins fabricated using plutonium obtained after reprocessing of mixed fuel irradiated in PWR. In 2017, the studies with fabrication of full-scale FA were to expensive, so that

The operation of a high-temperature fuel rod with a fuel kernel consisting of uranium dioxide is accompanied by significant changes in the initial structure of the fuel – a multi-zone dioxide structure with different grain size and shape (growth of initially uniaxial grains, formation of a columnar structure) can form in the transverse section of the kernel. For low level of stress appearing in the

The CELSIST subchannel module is described. The results of the simulation of experiments on the flow of liquid metal coolant in model FA are presented: lead-bismuth eutectic alloy in a 19-rod FA on the THEADES stand (Karlsruhe Liquid Metal Laboratory, Germany), sodium in a 19-rod FA on the Bundle 2A FFM stand (ORNL, USA), sodium-potassium eutectic alloy in a 37-rod FA on the 6B stand (IPPE, Russia)

The absorbed dose rate of external γ-radiation from two sources of radiation – surface soil layer and subsurface phytomass of plants in stand grass – is calculated by different methods. The calculation of the absorbed dose rate based on integration of the dose attenuation function of a point source taking into account the dose accumulation factor was compared with the results of a Monte Carlo solution

The possibilities of burning americium from spent nuclear fuel of thermal reactors in the operating BN-800 are examined. It is shown that because of the small fission cross-section in the neutron spectrum of a fast reactor all of the americium cannot be directly converted into fission products. This can be done only by transmutation of americium into plutonium, which must be separated and directed

The radiation conditions at a ship repair yard in Bukhta Chazhma after a nuclear accident on a submarine on August 10, 1985 were reconstructed by means of hindcasting taking into account a 3D model of the enterprise and dose rate measurements during the first few days after the accident. The submarine presented the greatest danger during the first few days. The dose rate was equal to 1500–2500 mSv/h

The startup of a space nuclear power system is conducted after the space vehicle is put into its operational orbit. The reactor is in a deeply subcritical state, it is technically unfeasible to use a startup source of neutrons, and ground-based operator intervention is excluded. Since payload usage before the nuclear reactor starts is supported by storage batteries, the problem of reducing the startup

Radioactive wastes are formed during the production of uranium-plutonium nuclear fuel at enterprises. In the present article the concentration ranges for uranium, plutonium, and neptunium in liquid and cemented wastes corresponding to different radioactivity classes are determined. The concentration ranges are determined for wastes formed in the production of nitride fuel for the initial load, as well

The definition of the separation potential for multicomponent separation is analyzed. The possibility of introducing a particular separation potential together with the general separation potential for concrete setups is examined. An expression is obtained for the particular separation potential of a gas centrifuge.

The neutron fluxes of D–D and D–T tubes with sorbed and stuffed targets are compared. Calculations of the change of the neutron flux in generators when a tube of one type is replaced by a tube of a different type are presented. The influence of the atomic-molecular composition of the ion beam and the target material, the hydride stoichiometry, and the isotopic composition of the gas in the getter is