Abstract: Accurate data on the neutron yield from the interaction of α-particles with the nuclei of light elements ranging from lithium to potassium are required for solving the problems of nuclear power technologies: development of analytical means for controlling the technological processes of fabricating and reprocessing nuclear fuel, securing radiological protection for workers, improving the systems for managing and monitoring nuclear materials and radioactive wastes, measuring the burnup fraction of spent nuclear fuel, and others. The uncertainty of this information must be <10% for energies ranging from 4 to 9 MeV of α-particles emitted by naturally occurring and artificial radionuclides. The computational uncertainty of the neutron yield can be reduced on the basis of a combined analysis of (α, n) reactions, measured on α-particle accelerators with tunable energy and on compounds of actinides with light elements, using reliable data on the stopping power of α-particles for elements from hydrogen to californium. The results of such an analysis based on experimental and evaluated data for the light isotopes 6Li, 7Li, 9Be, 10B, 11B, 13C, 14N, 17O, 18O, 21Ne, 22Ne, 19F, 23Na, 25Mg, 26Mg, 27Al, 29Si, 30Si, 31P, 33S, 34S, 35Cl, 37Cl, and 41K in the α-particle energy range from 4 to 9 MeV are presented. PubDate: 2015-02-18

Abstract: A method is proposed for concentrating in different output flows in a square cascade with two additional extractions the components of the multicomponent isotopic mixture being separated. The parameters of the proposed cascade, a square cascade with additional extraction, and a cascade with flow expansion at internal steps on condition that the number of separative elements in them is the same are compared for the separation of a mixture of tungsten isotopes. It is shown that the proposed cascade expands the possibilities of previously known methods of concentrating intermediate-mass isotopes, since several target products can be obtained at the same time in the output flows. PubDate: 2015-02-15

Abstract: The basic problems associated with the transition to supercritical coolant pressure in water cooled reactors are outlined: the need for deeper study of the heat and mass transfer, especially that occurring during flow in complicated spatial structures, in order to develop reliable computational methods and materials for fuel-element cladding that are capable of operating at elevated temperature under the conditions of high corrosion activity of the medium; securing an acceptable degree of safety and increasing the economic efficiency of NPP with a reactor with supercritical coolant pressure. The expediency of choosing a two-loop scheme for the reactor facility with an integrated arrangement of the first-loop equipment is validated. PubDate: 2015-02-15

Abstract: The reconstruction of fields and adjustment of the parameters of reactor models are increasingly prioritized for reactor physics because the efficiency and safety of the control of a nuclear plant depend on solving them. The results of reconstruction and parameter adjustments are largely determined by the probability distributions of the computed and measured data. The probability distribution of the computed data in turn depends on the properties of the neutron-physical model and probabilistic characteristics of the parameters of this model. The present work is devoted to the search for and investigations of efficient algorithms for calculating the covariation functions of the neutron flux density. A model of a stationary subcritical reactor with an internal neutron source is studied. Linear perturbation theory, the theorem on the spectral decomposition of operators, and the theory of stochastic processes are the tools used for performing the analysis. PubDate: 2015-02-15

Abstract: Research performed at the Bochvar All-Russia Research Institute for Inorganic Materials (VNIINM) and the All-Russia Research Institute of Experimental Physics (VNIIEF) on the development of the TUK-117 multipurpose transport packaging is presented. The TUK-117 packaging possesses biological protection based on depleted uranium and intended for transporting and storing spent nuclear fuel. The higher capacity of the metallic uranium alloy for absorbing of γ-rays and the alloy’s high mechanical characteristics have made it possible to develop a design meeting IAEA specifications. The technology for fabricating safety-engineered articles from uranium and its alloys by pouring the alloy into a prepared mold made of corrosion-resistant steel is patented. PubDate: 2015-02-15

Abstract: A reactimeter was developed for the IBR-2 periodic-pulse reactor. The reactor kinetics was described by difference equations, which relate the reactor’s parameters, corresponding to the instantaneous and preceding power pulses, and the nonlinear dependences of the energy of the power pulse and its amplitude on the reactivity. The fact that the regulated parameter of the reactor is the relative deviation of the amplitude of the power pulse from its base (prescribed average) value was taken into account. In studying transient processes, a statistically optimal filter was used to suppress the reactivity noise due to the reactor’s construction and principle of operation. The best location for inserting the filter in the block diagram of the reactimeter was chosen and the optimal smoothing coefficient determined. PubDate: 2015-02-15

Abstract: The electric and thermal conductivity of the aluminum alloys AMG-2 and SAV-1, which are used to fabricate the fuel elements of the fuel assemblies of a nuclear reactor, was investigated in the range 290–490 K. The Debye temperature was calculated and the contribution of the electronic and lattice components to the thermal conductivity of the alloys was determined. It is shown on the basis of an analysis of the mechanisms of electron and phonon scattering and the experimental data that one possible reason for the observed changes of the thermal conductivity in aluminum alloys are the scattering of electrons by phonons and the deviation of the Lorenz number from the theoretical values as a result of inelastic scattering of the electrons. PubDate: 2015-02-15

Abstract: The results of an investigation of the beam dynamics in a high-power proton accelerator-driver intended for operation as part of a subcritical electronuclear facility are presented. The initial normally conducting part of the accelerator at current 10 mA with current-passage ratio >95% has been developed. A channel with current-passage ratio 100% has been developed for the superconducting part of the accelerator. Modeling of the accelerating cavities for all velocity ranges has been done. High electrodynamic performance has been attained as a result of optimization. PubDate: 2015-02-15

Abstract: Heat-exchanger models in the SOKRAT-BN code which are used to calculate problems with boiling sodium in channels with different geometry are presented. The results of modeling of different experiments on boiling of liquid-metal coolant are presented. Good agreement is obtained between the SOKRAT-BN calculations and experiments performed with stationary and nonstationary boiling of sodium. It is shown that the thermohydraulic processes occurring in reactor facilities during design-basis and beyond design basis accidents can be calculated correctly using the thermohydraulic module of the SOKRAT-BN computer code. PubDate: 2015-02-15

Abstract: The results of a comprehensive analysis of the possibility of developing in our country a powerful proton accelerator-driver as an element of subcritical electro-nuclear facility are presented. The investigations are performed taking account of the latest advances of accelerator technology and the real capabilities of industry. The design layout developed for the accelerator is discussed. It is shown that in principle a prototype of a ~1 GeV accelerator-driver with current 1–5 mA, which can subsequently be increased to 10–15 mA, can be built in Russia. PubDate: 2015-02-04

Abstract: To evaluate detection characteristics by means of an analysis of γ-ray spectra, it is necessary to set a probability distribution for the number of counts that contains their mathematical expectation. In measurements, the mathematical expectation is a random quantity. These random quantities are averaged for the Poisson and Gaussian distributions. Calculations of the detection characteristics show that for a small average number of counts 10–100 the averaged Poisson distribution should be used. The Gaussian approximation and the ordinary Poisson distribution lead to large errors in the detection characteristics. PubDate: 2015-02-04

Abstract: The aims of this work were to compare the results of studies performed by the present authors using the existing data on the thermal conductivity of uranium mononitride and colligate and analyze the thermal conductivity of mixed uranium-plutonium fuel. The dependence of the thermal conductivity on the content of impurities and the porosity of a material was investigated. It was shown that there is a discrepancy in the experimental data. Since it determines the presence of impurities and porosity, the technology used to fabricate the fuel has a considerable effect on the change in the thermal conductivity. PubDate: 2015-02-04

Abstract: This article is devoted to the pressing issue of achieving fuel security by realizing in fast reactors the best breeding of new fissile materials from the initial isotopes and using the accumulated fissile isotopes in the same reactor irrespective of the rates at which the spent nuclear fuel is reprocessed in the external fuel cycle. Two fast-reactor concepts based on the same principle are validated by computational means. In the first one, the fissile isotope is replenished with the breeding isotope by moving the neutron flux or energy release along the initially formed composition, consisting of a seed zone and a breeding zone (traveling wave of fission concept); in the second one, the motion of the neutron flux is replaced by the movement of the fuel composition, comprised of fissile and breeding materials (standing wave of fission concept). PubDate: 2015-02-04

Abstract: This article is devoted to the development and study of new protective materials containing depleted uranium dioxide for increasing the capacity for γ-ray absorption. The materials were developed for use in multipurpose containers for spent nuclear fuel. The results of work on obtaining high-density concrete and cermet are presented. The recipe and technology for fabricating concrete (RZK–VNIINM) with density 6.5 g/cm3 have been patented. A method of obtaining a high-density composition of corrosion-resistant steel and depleted uranium dioxide (cermet) with density 8.3 g/cm3 has been developed. PubDate: 2015-02-04

Abstract: The results of radioecological studies performed on reserved sections of geological-exploration work and mining of radioactive metals (uranium, thorium) in Yakutiya are presented. The work included measurement of the γ-ray exposure dose rate and concentration of natural radionuclides (potassium, uranium, and thorium) on the surface of radioactive rock dumps by means of a radiometer and a gamma spectrometer. The radioactive rock dumps are ranked by the exposure dose rate and the computed specific effective activity of radionuclides. It is shown that radioactive rock dumps can be sources of radioactive contamination of the soil and vegetative ground cover of landscapes. PubDate: 2015-02-04

Abstract: The model of a heat-exchange crisis used in the PUChOK BM-DF code, intended for calculating by means of elementary cells the local thermohydraulic parameters of water and a steam–water mixture during stationary flow in fuel rod assemblies, was verified. The verification was done on experimental data obtained on the PSB RBMK thermohydraulic stand (Electrogorsk Research Center for Nuclear Power Plant Safety), which models one circuit of the multiple forced circulation loop in RBMK and includes a model of all main elements of the loop. The experimental investigation was performed in order to determine the effect of changes in the geometry of RBMK channels on the conditions for the appearance of a heat-exchange crisis. It was shown that in terms of the local parameters the computed critical power agrees with the experimental data. PubDate: 2015-02-04

Abstract: For future nuclear power with fast reactors with sodium (BN-1200) and lead (BREST) as coolants, plans are being made to use mixed uranium-plutonium nitride fuel as part of the Proryv project. A technology for carbothermal synthesis of mixed uranium-plutonium mononitride fuel and fabrication of pellets from it has now been developed. A program of comprehensive computational and experimental research on fuel to study the initial properties and their change under irradiation in reactor experiments is being implemented. Some results of pre-reactor studies of the properties of fuel and a program for future research are presented. PubDate: 2015-02-04

Abstract: The results of the application of three Monte Carlo approaches to modeling the formation, condensation, and coagulation of single-component aerosol particles are analyzed. It is shown that for calculations with condensation included the mass-flow algorithm is more efficient than direct modeling. PubDate: 2015-02-04