Power Engineering Institute Research Articles

Heat-transfer crisis in channels

1. A modern version of a look-up table has been developed for calculating the critical heat flux in round pipes on the basis of the combined work of specialists at Chalk River Laboratory (Canada), the Main Science Center of the Russian Federation — the Physics and Power Engineering Institute, and the Technical University in Braunschweig (Germany). The table is based on a databank on the critical heat flux density in pipes with a vertical rising flow of water. The bank includes a wide range of regime parameters. The table is intended for calculating the critical heat flux density in pipes with a diameter of 8 mm in a range of pressure, mass velocity, and critical mass steam content equal to 0.1–20 MPa, 0.25–8 Mg/(sec·m2), and from −0.5 to 1, respectively. Linear extrapolation is used to calculate qcr in intermediate regimes. An empirical relation is introduced in order to expand the applications of the look-up table to calculations in pipes with a different diameter. The table obtained on the basis of a combined Russian-Canadian databank contains, after the redundancies and clearly incorrect values are removed, 22946 values of the critical heat flux densit with an arithmetic mean and rms error of 0.69 and 7.82%, respectively. Assessment of the preceding versions and empirical correlations showed that this look-up table makes possible today the most accurate calculations and is applicable for a wide range of parameters.

Main science center of the Russian federation — A.I. Leipunskii physics and power engineering institute

Main science center of the Russian federation — A.I. Leipunskii physics and power engineering institute

Inelastic Neutron Scattering by235U and238U Nuclei

Inelastic scattered neutron spectra and fission neutron spectra for 235 U and 238 U at incident neutron energies of 1.17, 1.79, and 2.19 MeV were measured by the neutron time-of-flight spectrometer at the Institute of Physics and Power Engineering. A solid tritium target was used as the neutron source. The experimental data were simulated by a Monte Carlo code. The interaction of beam protons inside the target, the reaction kinematics, and multiple scattering in the samples were taken into account. The data were normalized with respect to the C(n,n) and 235 U(n,f) standard reaction cross sections. The experimental results were verified against absolute fission spectrum measurements by using well-known fission cross-section and v values. The Maxwell distribution parameters for the fission spectra, the total inelastic scattering cross sections, and the inelastic scattered neutron spectra were derived. The results of this work confirm the ENDF/B-VI evaluations for 238 U are very close to those of ENDF/B-VI. however, substantial discrepancies exist between our experimental data for 238 U and the ENDF/B-VI and JENDL-3 evaluations concerning the excitation functions for levels between 0.5 and 1.2 MeV and continuum spectra

First results of millisecond pulsar 1937+21 timing by TNA-1500 radio telescope of Special Research Bureau of Moscow Power Engineering Institute

Regular timing observations of the millisecond pulsar PSR 1937+21 at a frequency of 610 MHz by means of the TNA-1500 radio telescope with a fully steerable 64-m antenna have begun at the Bear Lakes Radio Observatory of the Special Research Bureau of the Moscow Power Engineering Institute. A 40-channel spectrum analyzer and a system for high-speed recording and acquisition of observation data are connected to a reference clock by means of CAMAC interfaces and an 80286 control computer. The reception band is 1.6 MHz (40 channels of 40 kHz each). The total noise temperature of the system is on the order of 160 K. The signal-to-noise ratio is on the order of 50 for a 30-min observation of the pulsar. The mean-square error of measurement of the pulse arrival time is 400 nsec. Data on pulsar 1937+21 along with timing results for “normal” reference pulsars PSR 0834+06 and PSR 1919+21 obtained at the Pushino Radio Observatory of the Lebedev Physics Institute over a period of 13 years will be used to construct a pulsar time scale.

Perspective channel-type reactor with enhanced safety

Following the search for new design solutions to develop within the framework of channel trends the reactor with enhanced safety the Research and Development Institute of Power Engineering has developed the design of the multiloop boiling water reactor (MKER). The MKER enhanced safety is attained when involving the inherent safety features, passive safety systems as well as the accident consequences confinement devices. The design realizes several advantages which are typical of the channel-type reactors, namely: the design desintegration simplifying the manufacture, control, equipment delivery and decreasing, versus the pressure vessel reactors, the accident effect if it proceeds in an explosive manner; small operating reactivity margin and fuel burnup increased due to continuous refuelling; fuel cycle flexibility allowing comparatively easily to adopt the reactor to the conjuncture of the country fuel balance; multiloop circuit of the main coolant which reduces the degree and effect of the accidents connected with the equipment and pipings rupture; monitoring of the channels and fuel assemblies leak-tightness.

Experimental and theoretical works performed by the Institute of Physics and Power Engineering on the physics of nuclear-induced plasmas

In review, general results obtained by Institute of Physics and Power Engineering (IPPE) during 1981–1992 are presented in the field of physics of nuclear-induced plasmas in the following directions: processes of primary ionization of different media by nuclear reaction products; function of electron distribution in nuclear-induced plasmas; processes of excitation and relaxation; track structure of nuclear-induced plasmas. Prospects of study progress are discussed with a view to improve the current concepts of physics of elementary processes occurring in nuclear-induced plasmas and obtain experimental and theoretical data on process constants needed to calculate the nuclear-pumped lasers.

Solid state nuclear track detectors used for measurements on critical assemblies of the Nuclear Power Engineering Institute of the Academy of Sciences of Belarus

Use of the solid state nuclear track detector methods for the experimental study of neutron physical characteristics of nuclear reactors has been developed in the Nuclear Power Engineering Institute of the Academy of Sciences of Belarus. A series of solid state nuclear track detectors has been tested and two of them have been chosen: artificial mica for detection of fission fragments and cellulose triacetate for detection of α-particles. The basic neutron field characteristics of both fast and thermal reactors have been obtained by this method.

Solid state nuclear track detectors used for measurements on critical assemblies of the Nuclear Power Engineering Institute of the Academy of Sciences of Belarus

Use of the solid state nuclear track detector methods for the experimental study of neutron physical characteristics of nuclear reactors has been developed in the Nuclear Power Engineering Institute of the Academy of Sciences of Belarus. A series of solid state nuclear track detectors has been tested and two of them have been chosen: artificial mica for detection of fission fragments and cellulose triacetate for detection of α-particles. The basic neutron field characteristics of both fast and thermal reactors have been obtained by this method.

Fatigue resistance of steels: Boardman, B. Metals Handbook 10th Edn (ASM International, Materials Park, Ohio, 1990) Vol. 1, pp 673–688

In the recent literature, the influence of lean fuel, type of fuel, velocity profile and the flow direction on the performance operation of solid oxide cells (SOCs) is commonly investigated. SOCs generate electricity when they operate in fuel cell mode (SOFC – Solid Oxide Fuel Cell) or produce hydrogen in electrolysis mode (SOEC – Solid Oxide Electrolyzer Cell). They consist of several layers, including two porous electrodes separated by a gas-tight electrolyte. Typical anode porosity (fuel electrode in SOFC mode) varies from 20% to 50% (after sintering). The porosity value may limit the mass transport and the overall performance of SOC. This work investigates computationally and experimentally, the existing challenge such as diffusion mechanism in porous medium using the example of SOC electrode. A set of mass transport models (Fick's laws, modified Fick's law, Maxwell-Stefan Model, Dusty Gas Model) are described and discussed, highlighting their similarities, differences, advantages, and disadvantages as well as restrictions in usage. Finally, a detailed computational fluid dynamics (CFD) model of the diffusive transport in porous electrode was elaborated and validated. An experimental campaign was conducted using anode supported SOC, fabricated at the Institute of Power Engineering in Poland. Simulations were performed of the mass transport of pure hydrogen and pure water vapor or carbon dioxide (substitute of real product of electrochemical reaction in SOC for validation purposes) through porous anode. Tests were conducted in the wide flow range 10 [ml/min] up to 200 [ml/min] for both gases. The results demonstrate that hydrogen mole fractions reached similar values (0.5–0.6) at both outlets only for the maximum residence time or high porosity of anode. This implies that residence time and gas diffusion can be controlled by a combination of operating and microstructural parameters and can be estimated by numerical simulation using computational fluid dynamics. The main motivation and outcome of this work were to reduce the cost and time required for the optimization of the mass transport process through SOC's porous electrode.

The influence of voltage variations on the reactive power consumption

During power shortages in the Polish electric power system, appropriate voltage reductions are sometimes carried out. At the Electric Power Engineering Institute of the Technical University in Wrocław, Poland, a so-called reactive power voltage control coefficient during a voltage reduction has been successfully defined and evaluated. This coefficient has been defined as the percentage variation of reactive power consumption effected by a suitable percentage voltage variation (voltage reducing, generally). Several network nodes in the power system were tested. Computer-aided weekly digital measurements of the morning and evening peak loads during forced voltage reductions of up to 5% were carried out. This article presents the mean value of the reactive power voltage control coefficient and also its weighted average. It was proved that this calculated coefficient ranged from 2.5 to 7.1. The voltage reduction should not exceed 5% of the voltage rating.

Concrete and concrete structures: Aug. 17–21, 1987 Division H, will meet during the 9th Internation conference on structural mechanics in reactor technology, Ecole Polytechnique Fédérale de Lausanne, Switzerland. Information: Prof. Z.P. Bazant, Dept. of Civil Engineering, Northwestern University, Evanston, IL 60201 USA; or Dr. Thomas Zimmerman, Institute of Energy Economics and Power engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne,

Concrete and concrete structures: Aug. 17–21, 1987 Division H, will meet during the 9th Internation conference on structural mechanics in reactor technology, Ecole Polytechnique Fédérale de Lausanne, Switzerland. Information: Prof. Z.P. Bazant, Dept. of Civil Engineering, Northwestern University, Evanston, IL 60201 USA; or Dr. Thomas Zimmerman, Institute of Energy Economics and Power engineering, Swiss Federal Institute of Technology, CH-1015 Lausanne,

Measurement of the ratio of the232Th and235U fission cross sections in a neutron energy range 5?10 MeV

The ratios of the /sup 232/Th and /sup 235/U fission cross sections were measured with the aid of a pulsed deuteron beam of the EGP-10M charge-exchange accelerator at the Physics and Power Engineering Institute, Obninsk. As the neutron source we used the D(d, n)/sup 3/He reaction in a gaseous deuterium target. Fissions of /sup 232/Th and /sup 235/U nuclei were recorded with a fast double ionization fission chamber filled with methane to a pressure of 1.5 x 10/sup 5/ Pa. The detection efficiency for fission fragments that entered the effective volume of the detector was 99.2 +/- 0.7%. The energy dependence of the cross-section ratio was measured with the aid of thin films of thorium and uranium oxides deposited onto aluminum substrates. The energy dependence of the ratio of fission cross sections was made absolute by using thorium targets which contained a small /sup 235/U impurity. The background of the experimental room was determined from the time spectra and had little effect on the results of the measurements.

Authors

Authors

Search for signals from extraterrestrial civilizations by the method of synchronous dispersion reception

It is suggested that optimal call signals of extraterrestrial civilizations are rare pulse signals in the decimeter and centimeter bands. Problems related to the optimization of equipment for the search for such signals are considered. To detect remote radio emission sources, highest sensitivity can probably be realized using the method of synchronized reception for two (or more) widely spaced stations and by selecting among received signals those with characteristic properties related to dispersion in intersteller matter. Staff members of the Institute of Space Research jointly with the Shternberg State Astronomical Institute of Moscow State University, the Moscow Power Engineering Institute, and the V. I. Lenin Moscow State Pedagogical Institute, prepared suitable equipment for the 350–550-MHz and 13,700–15,200-MHz frequency bands and, in 1972, carried out a series of measurements on a 3000-km base. The results obtained from a consideration of the experimental data are presented.

U.S. - U.S.S.R. cooperation in superconducting power transmission

The cooperative exchange between the U.S. and the Soviet Union in the field of superconducting power transmission began in 1971 when a U.S. delegation representing government and industry met with a Soviet delegation in Moscow. The following year a Soviet delegation met in the U.S. and this alternating pattern has continued to the present. The development and guidance of the cooperation by these yearly meetings of delegations from the coordinating committee is described in context with the evolving U.S. and Soviet national programs to develop superconducting power transmission. The U.S. national program is now concentrated in the projects at the Brookhaven National Laboratory and the Los Alamos Scientific Laboratory while the Soviet program is concentrated in projects at the G. M. Krzhizha-novsky Power Engineering Institute, the All-Union Research Institute for the Cable Industry and the Lenin All-Union Electrotechnical Institute. These projects are briefly reviewed along with the supporting projects in other institutions in both countries. The detailed planning for the cooperation is carried out by six technical working groups whose members are drawn from the broad technical community that supports the national programs. These groups also report on the technical progress in each country. To facilitate these reports, five joint technical symposia have been held, one at each of the delegation meetings except for the 1977 meeting in Moscow. Highlights of these symposia will be presented. At the present time the cooperation is focused on joint participation in both the small scale laboratory studies and large scale test installations which each country is conducting as part of its national program. The results from the eight joint experiments conducted since 1971 will be presented along with some of the future plans and prospects.

Some problems of the mechanics of polymeric composites

Work on the mechanics of polymer composite materials and structures carried out in the Moscow Power Engineering Institute during the last 5 years is reviewed. The review covers work on the theory of reinforced media and its application to composite sturctures, the theoretical and experimental investigation of the effect of technological factors on the reliability of composite structure, the theory of hardening viscoelastic media, and the mechanical testing of specimens and models of polymer composites.