Obninsk Institute of Physics and Power Engineering

Obninsk, Russia

Obninsk Institute of Physics and Power Engineering

Obninsk, Russia
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Morozov A.V.,Obninsk Institute of Physics and Power Engineering | Sakhipgareev A.R.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2017

The paper presents the results of experimental study of the effect of contact condensation of steam-gas mixture on the operation of VVER passive safety systems and the steam generator in emergency condensing mode. The contact condensation takes place when subcooled fluid is supplied in the accumulator tank of VVER reactor facility passive core flooding system (the HA-2 system) in the presence of non-condensable gases. Water supplied to the second stage of hydro accumulators can be used for increasing the operating time of the VVER steam generator in the emergency condensing mode and ensuring longer core cooling. Low liquid outlet velocity (less than 1 m/sec), necessitated to ensure safety systems operation in passive mode constitutes the distinguishing feature of the investigated processes. The experiments were performed on the test facility with the parameters specific to the primary circuit of the reactor facility within 24 hours after the accident initiation for different concentrations of gas in the steam-gas mixture. Nitrogen and helium, which replaces hydrogen, were used as the non-condensable gases. It was established as the result of the experiments that the increase of concentration of non-condensable gas in the volume the HA-2 hydro accumulator model up to 45% leads to the reduction of intensity of contact condensation of steam from the steam-gas mixture by ∼29% in the experiment with nitrogen and by ∼57% in the experiment with helium. The obtained experimental data can be used for numerical simulation of emergency processes in the VVER reactor facility during operation of passive safety systems taking into account the removal of steam-gas mixture from steam generator by supplying the subcooled liquid jet into the volume of second stage HA-2 accumulator tanks.


Lvova E.M.,Obninsk Institute of Physics and Power Engineering | Chebeskov A.N.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2017

By now, a fairly stable concept of «attractiveness of nuclear materials» has been formed in scientific literature. This term implies that nuclear materials which are in the civil fuel cycle may be used for making primitive nuclear explosive devices or even nuclear weapon. This concept serves as a comparative analysis of various nuclear materials for their possible unauthorized application. Attractiveness of nuclear materials is primarily defined by their nuclear physical properties, i.e., properties inherent in these materials. First of all, these properties include the capability of the considered material to produce a self-sustaining chain reaction. Otherwise, this material will be absolutely unattractive for the above-mentioned purposes. Besides this main property, important characteristics of nuclear materials influencing their attractiveness are the neutron background and heat emission. This paper presents an analysis of fuel compositions in the fuel cycle of naturally safe BR-1200 fast reactors (BREST-1200) with an on-site NFC infrastructure in terms of their attractiveness. The objects of research are the elementary systems in the form of spheres containing nuclear materials of the BR-1200 fast reactor fuel cycle without neutron reflectors and surrounded with such reflectors made from various materials. At the same time, for each system its critical state is defined and the main properties characterizing the attractiveness of nuclear materials are calculated, taking into account materials and thicknesses of the neutron reflectors.


Zhuravlev B.V.,Obninsk Institute of Physics and Power Engineering | Titarenko N.N.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2017

The experimental verification of neutron inelastic scattering cross section on iron have been performed on the basis of neutron inelastic spectra measurements at neutron incident energies of 6.0, 7.0 and 8.0 MeV and their calculations in the framework of nuclear reactions statistical theory and direct interaction. Cross sections of neutron reactions present great interest in the context of nuclear technology. Iron is a structural material for different nuclear energy plant and has been proposed as gamma-ray cross-section standard. In spite of a big efforts agreement between the various measurements is poor and various data evaluations reflect this situation. The measurements of the inelastic scattering neutron spectra were performed by the time-of-flight fast-neutron spectrometer on the base of the EGP-10M pulsed tandem accelerator of the Institute for Physics and Power Engineering (IPPE, Obninsk). An analysis of measured data have been performed with use of the Hauser-Feshbach mathematical formalism of the statistical model for equilibrium emission, preequilibrium model and direct mechanism of nuclear reactions. The results of present work agree in the limits of the measurement errors with data of work on the measurement of gamma-ray production cross-sections performed in Los Alamos [7] and with new data obtained at the photo-neutron source nELBE [23]. The obtained results show on need of correct of library of recommended evaluated neutron data BROND-2.2 for inelastic scattering cross section on iron in the direction of their increase and possible small correct of library of recommended evaluated neutron data BROND-3.


Malynkin V.G.,Obninsk Institute for Nuclear Power Engineering | Platonova E.V.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2017

It was found that under the influence of ion-plasma treatment radiation-induced structural-phase transformations in the high-alloy superalloy Fe-15Cr-35Ni-11W differ from the transformations in steels of the type 0X18H10T and 0X16N15M3B, widely used in nuclear power engineering. These differences were established with the help of X-ray analysis, which showed that additional reflections on the X-ray patterns of irradiated samples of the Fe-15Cr-35Ni-11W alloy appear from the side of large angles relative to the reflections of the initial solid solution. At the same time, detailed X-ray diffraction studies carried out by the authors earlier showed that X-ray diffraction patterns of iron-chromium alloys of the type 0X18 (10-30) H, additionally doped Ti, Mo, Nb, Al in an amount of 1-3% and irradiated with ion-plasma The additional peaks appeared from the side of smaller angles. It is established that in both cases the formed phase is isomorphic to the matrix phase and is thermally metastable, and unlike the 0X18H10T steel, the Fe-15Cr-35Ni-11W alloy undergoes softening. The analysis of literature data on the causes capable of causing similar structural-phase transformations in materials subjected to intensive ion-plasma treatment is analyzed. The concentration of package defects in the alloy Fe-15Cr-35Ni-11W and the steel 0X18H10T in the deformed state was determined by the X-ray diffraction analysis. It was found that the concentration of packing defects in this state in steel 0X18H10T is 4 times higher, which indicates a lower packing defect energy Steel 0X18H10T. It is concluded that the observed effects are associated with the mechanism of radiation-induced plastic deformation. In the Fe-15Cr-35Ni-11W alloy, structural-phase changes are associated with deformation by twinning, in contrast to 0X18H10T steel, in which the observed transformations are due to slip deformation.


Tolokonnikov S.V.,Moscow Institute of Physics and Technology | Kamerdzhiev S.,Obninsk Institute of Physics and Power Engineering | Krewald S.,Jülich Research Center | Saperstein E.E.,RAS Research Center Kurchatov Institute | Voitenkov D.,Obninsk Institute of Physics and Power Engineering
European Physical Journal A | Year: 2012

The quadrupole moments of odd neighbors of semi-magic lead and tin isotopes and N = 50, N = 82 isotones are calculated within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. Two sets of published functionals are used to estimate systematic errors of the present self-consistent approach. They differ by the spin-orbit and effective tensor force parameters. The functional DF3-a leads to quadrupole moments in reasonable agreement with the experimental ones for most, but not all, nuclei considered. © 2012 SIF, Springer-Verlag Berlin Heidelberg.


Kalashnik M.V.,Obninsk Institute of Physics and Power Engineering | Chkhetiani O.G.,Russian Academy of Sciences
Fluid Dynamics | Year: 2016

The problem of the stability of an isolated jet flow and two counter-streaming jet flows in a rotating shallow-water layer is considered. These flows are described by exact solutions of the Charny–Obukhov equation with one or two discontinuities of the potential vorticity, respectively. The isolated jet flow is shown to be stable. For the system consisting of two jet flows the dependence of the characteristics of the unstable wave modes on a geometric parameter, namely, the ratio of the spacing between the jet axes to the deformation radius, is determined. On the basis of the contour dynamics method a weakly-nonlinear model of the longwave instability is developed. © 2016, Pleiades Publishing, Ltd.


Rezvykh K.A.,Obninsk Institute of Physics and Power Engineering | Romanov V.A.,Obninsk Institute of Physics and Power Engineering
24th Russian Particle Accelerator Conference, RuPAC 2014 | Year: 2014

New effective technique of conditioning of gaseous insulation of electrostatic accelerator is described. To achieve stable breakdown voltage, accelerator conditioning procedure would take 7-8 hours (volume of pressure tank is 93 m ). Three methods of monitoring cleanness of gaseous insulation are proposed. © 2014 CC-BY-3.0 and by the respective authors.


Raskach K.F.,Obninsk Institute of Physics and Power Engineering
Physics of Atomic Nuclei | Year: 2012

In multigroup calculations of reactivity and sensitivity coefficients, methodical errors can appear if the interdependence of multigroup constants is not taken into account. For this effect to be taken into account, so-called implicit components of the aforementioned values are introduced. A simple technique for computing these values is proposed. It is based on the use of subgroup parameters. © 2012 Pleiades Publishing, Ltd.


L'vova E.M.,Obninsk Institute of Physics and Power Engineering | Chebeskov A.N.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2016

Nuclear fuel cycle of fast reactors contains material which is directly or with some additional processing can potentially be used to manufacture a primitive nuclear explosive device or even for the production of powerful nuclear weapons. When considering the problem of non-proliferation of nuclear weapons and nuclear terrorism it is customary to apply to such materials the notion of attractiveness, in other words, to evaluate the potential use of these materials in undeclared activities. The attractiveness of nuclear materials in the first turn is estimated according to their intrinsic neutron-physical properties. The value of critical mass is a key characteristic in the choice of nuclear material that can be used to manufacture nuclear explosive devices. In addition to critical mass, important characteristics of nuclear materials are neutron background and heat generation. The high neutron background will inevitably lead to the premature start of the chain fission reaction - predetonation, which practically excludes the possibility of nominal energy yield. Significant level of heat generation of nuclear material complicates its treatment, but the main factor is the influence of high temperature on the degradation of chemical explosives, which is directly adjacent nuclear material and at a sufficiently high temperature of nuclear material the chemical explosive loses its properties and breaks the performance of a nuclear charge. This paper presents the results of the study of the attractiveness of different types of fuel compositions according to their neutron-physical properties as applied to the fuel cycle of sodium fast reactor of high capacity (BN-1200 type) for different options of the reactor start loading and reaching steady-state conditions. The objects of the study are the simplest systems in the form of spherical assemblies containing the fuel compositions of the fast reactor BN-1200 type without reflectors and surrounded by elementary neutron reflectors. Critical state is defined for each such a system and for this state main neutron-physical properties are calculated.


Manturov G.N.,Obninsk Institute of Physics and Power Engineering | Nikolaev M.N.,Obninsk Institute of Physics and Power Engineering
Izvestiya Wysshikh Uchebnykh Zawedeniy, Yadernaya Energetika | Year: 2016

Equation transport of neutron and gamma radiation in the energy, essential in the calculations of fast reactors and radiation shielding, does not contain any significant approximations - the accuracy of its solution is determined almost entirely accurate knowledge of the characteristics of the interaction of radiation with matter and, only partially, of correctness of computational techniques. Providing computational codes with reliable data about the characteristics of the interaction is the responsibility of the sectoral metrological service. Bringing methods of using these characteristics in the calculation of radiation fields in accordance with the state of knowledge of these characteristics should be one of the most important tasks in developing a new generation of codes. Hereafter the priorities in this direction are considered that must be addressed when developing a new generation of constants supplying software for fast reactor calculations as it is a unified system ABBN-2020 of multigroup neutron nuclear physics constants obtained on the basis of files ROSFOND national neutron data library. At the same time, along with the creation of a perfect system to ensure nuclear constants calculations, a considerable attention must be paid to the development and creation of methodology and computer code system for the evaluation and ranking of the estimated errors in the calculation of nuclear reactors in order to be concentrated on the most important issues. Creating of a new generation unified nuclear constants support system ABBN-2020 and its implementation in the design codes will not only ensure uniformity neutron constants preparation procedures, which will increase the reliability of their verification, but also improve the accuracy and reliability of predictions of the most important characteristics of the designed reactors, providing their license purity, competitiveness and independence from foreign developments.

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