PIK-2 Reactor with a Low Consumption of High-Enrichment Uranium

Calculations of the possibility of switching the matrix of the fuel-element cores and the vessel with the reactor envelope to weakly neutron-absorbing aluminum and lowering at the same time the fuel content in the fuel elements by 40% are performed for the high-flux PIK reactor which is under construction in Gatchina. As a result, the flux density of the thermal neutrons in the heavy-water reflector increases by a factor of 1.4–1.5 and the maximum unperturbed flux reaches a world record value – 1.9·10¹⁵ sec^–1·cm^–2. The nonuniformity of the volume energy-release decreases to 2.3. The weight of the control rods and reactor safety increase. As a result of the decrease of the fuel content in the fuel elements and the increase of the run duration, about 60 kg of high-enrichment uranium ²³⁵U are saved annually, decreasing annual fuel costs by one third.     

Studies of physical phenomena in semiconductor nanostructures using samples with laterally nonuniform layers. Photoluminescence of structures with n-type δ-doped layers

Photoluminescence of a structure based on GaAs with δ-doped n-type layers is studied experimentally at 77 K in the context of a previously suggested spectral-correlative method for investigating semiconductor structures with laterally nonuniform layers. This method makes it possible to study (for the same sample) the features of the observed multicomponent photoluminescence spectrum in relation to two parameters, i.e., the distance between the δ-doped layers and the width of a narrow InGaAs quantum well located between these layers. The results obtained make it possible to relate the observed exponential increase in the intensity of photoluminescence from the region of δ-doped layers as these parameters are varied to the variation in the ratio between the concentration of the holes laterally localized in the minimums of the fluctuation potential and that of free two-dimensional holes. An effect of stabilization of the energy position of the photoluminescence spectral lines is observed; this effect is related to the localization of holes in the potential well between the δ-doped layers. The experimental data obtained are consistent with the results of our numerical calculations.     

Absence of tolerance to the aversive stimulus properties of ethanol following oral ethanol self-administration

Aluminum has been reported to inhibit long-term potentiation (LTP) following in vivo administration and decrease glutamate release following in vitro exposure. Because glutamate release is critical for synaptic transmission and the development and maintenance of LTP in the hippocampus, we examined the effects of aluminum chloride (AlCl3) on depolarization-induced glutamate release and LTP in rat hippocampal slices. The effects of AlCl3 on [14C]glutamate release were examined by incubation of slices in depolarizing (56 mM)K+ buffer solution in the absence or presence of 2 mM CaCl2. After 15 min depolarization, AlCl3 (100-1000 microM) did not significantly affect Ca(2+)-dependent [14C]glutamate release from slices, whereas a known Ca2+ channel blocker (100 microM CdCl2) decreased Ca(2+)-dependent [14C]glutamate release by approximately 50%. In contrast to a previous report, acute exposure to AlCl3 was without effect on depolarization-dependent glutamate release. LTP of the population spike (PS) in CA1 of hippocampus was induced by the delivery of stimulus trains to the stratum radiatum. LTP of the PS was observed in both control slices and slices bathed in solution containing 100 microM AlCl3. Neither the magnitude nor longevity (measured up to 1 h posttrain) of LTP distinguished control from aluminum-exposed slices. The lack of sensitivity in rat to the encephalopathic changes induced by aluminum, or methodological differences in exposure conditions may account for the lack of effect of aluminum on in vitro LTP in rat hippocampus.     

Chemical potential of a metal as a criterion of corrosion-mechanical fracture

Odessa Technological Institute of the Food Industry, Odessa. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 30, No. 1, pp. 124–125, January–February, 1994.     

Effect of electrolytic hydrogen charging on the corrosion activity of a freshly formed surface of V92ts alloy

For V92ts aluminum alloy, it is established that electrolytic hydrogenation of a freshly formed fracture surface does not affect its electrode potential regardless of alloy aging conditions. However, the relaxation time of the potential of the hydrogen-charged freshly formed alloy surface and its corrosion intensity depend on the aging conditions.Lomonosov Odessa Technological Institute of the Food Industry, Odessa. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 5, pp. 106–107, September–October, 1993.     

Surface Hardening of Alloy Steels Using a High Intensity Electron Beam

Energy sources such as electron or laser beams have been extensively used for materials processing. Surface hardening is an established process used in industry. A combination of nitriding and electron beam treatment is used to modify alloy steel with nominal composition (wt.%) of 0.42% C, 0.96% Cr, 0.6% Mn, 0.37% Si, balance Fe. The hardness of the hardened layer varies in the range 800-850 HV. The high hardness is due to a refined microstructure consisting of a -solid solution (nitrous martensite) and γ - solid solution (nitrous austenite) and dispersed fine nitride precipitates. The wear resistance the of electron beam treated layer is double that of the ion nitrided specimens.     

Numerical study of the anisotropy of wave responses from a fractured reservoir using the grid-characteristic method

This work is aimed at studying the problem of subsurface disturbance propagation in a massive rock containing various inhomogeneities: empty or filled cracks. Numerical solutions to the problems of wave propagation in such substantially inhomogeneous media have been obtained. The dependence that the parameters of the response from a fractured reservoir have on the problem parameters is studied. The latter parameters are the density of the crack location, the fractured reservoir extent, amount of cracks, the initial disturbance location, crack inclination, and disturbance frequency. The concept of response anisotropy is introduced and the dependence that the anisotropy has on the abovementioned parameters is studied.     

High-Speed Semiconductor Voltage Regulators for On-Load Distribution Network Transformers

Power Technology and Engineering - The paper presents the results of developing a high-speed semiconductor transformer voltage regulator (STVR) intended for a real-time voltage regulation of 0.4 kV...