Deformation systems of α-zirconium

The deformation systems of -zirconium iodide have been studied in coarse-grained polycrystalline specimens deformed by upsetting. The orientation of the grains was determined from Laue patterns obtained in a special back-reflection camera using a small-diameter beam. The indices of the deformation systems were determined by the two-surface method and by the pole locus method.It was found that -zirconium is deformed by slip along the plane in the direction and along the plane. A number of twinning systems have been discovered In -zirconium: a) K₁ , 1 , K₁ , ₂ and s=0.173; b) K₁ , ₂ [1126], K₂ (0001), ₂ [1120] and s=0.629; c) K₁ (1122), ₁ [1123] and in one case, d) K₁ , ₁ .     

Dosimetry method for β radiation based on investigations of the electron spectra in the fields of β emitters

A method has been developed for -ray dosimetry based on the investigation of the effective electron spectra in the fields of emitters. The spectra was investigated with the help of a scintillation spectrometer. It was shown, that the value of the dose , where N is the number of particles penetrating an infinitesimal volume around the point being considered; is the value of the ionization loss averaged over the spectrum. It was established that the quantity is determined by the maximum energy of the spectrum of the isotope and may be considered to be independent of the depth of the medium and of the source diameter. Curves of depth doses for S³⁵, Tl²⁰⁴, Y⁹¹, and Ce¹⁴⁴ + Pr¹⁴⁴ are given and criteria for selecting isotopes to provide optimal conditions of irradiation are established.     

Some data on the spontaneous fission of Cm244

The average kinetic energy of the fission fragments, , the distribution width at half the height, E_k = 24.8 ± 2.5 MeV, and the average number of prompt neutrons per fission, = 2.71 ± 0.04, are found for the spontaneous fission of Cm²⁴⁴. The variation of and as functions of the nucleonic composition of the fissionable nucleus is considered in connection with the experimental results. Attention is drawn to the correlation of anomalies in these functional relationships as the most probable fragment mass varies. The assumption that the observed effects are related to a variation in the elastic properties of the fragments produced is discussed.Translated from Atomnaya Énergiya, Vol. 17, No. 1, pp. 28–34, July, 1964     

Nuclear information obtainable from low energy neutron spectroscopy

The results of measurements of thermal-neutron cross sections, level distributions in the resonance region, ratios, and determinations of the effective nuclear radius from potential:.scattering of slow neutrons are considered.A discrepancy in the results of measurements of the thermal-neutron fission cross secticn in U²³⁵ is noted. The distribution of levels exhibits a deficiency in small spacings as compared with a random distribution, i. e., there seems to be a repulsion of levels. The dependence of on atomic number A is nonmonotonic, in accordance with the complex-potential model of the nucleus; however there is a considerable discrepancy between the experimental data and theory for atomic numbers in the neighborhood of 100. The effective radius determined from potential scattering of slow neutrons indicates a nonmonotonic dependence on A, in agreement with the model of a semi-transparent nucleus with smeared-out edges.     

Chemical potential of oxygen of UO2 close to stoichiometry

Conclusions A closed solid electrolyte cell, permitting reliable values of to be obtained up to –775 kJ/mole, using a ceramic oxygen pump of stabilized ZrO₂, was developed. The temperature dependence of of uranium dioxide was determined for O/U=2.0039; 2.0021; 2.0018; 2.0012; 2.0009, and 2.0006. Coulometric titration of uranium dioxide was performed in the range of O/U from 2.0039 to 1.9991, and the influence of the degree of nonstoichiometry on was studied at 1273°K. A very strong dependence of at 1273°K was demonstrated in the range of O/U from 2.0001 to 1.9999. A change in O/U by 0.01% causes a 70% decrease in .Translated from Atomnaya Énergiya, Vol. 51, No. 4, pp. 228–230, October, 1981.     

Average energies of electron and positron β spectra

The average energies of electron and positron spectra were calculated for various values of the atomic number Z of radioactive nuclei and the timiting energy E₀ of the spectrum. The calculations were carried out for the case of allowed transitions and unique transitions of the first order of forbiddenness. The report contains tables and graphs of the values of and = f(E₀, Z) which may be used in evaluating the thermal effects of various radioactive specimens, nuclear reaction products, and products resulting from the fission of dements under the action of slow neutrons and high-energy nucleons, in calorimetric measurements of radioactive sources, and in calculating certain dosimetric characteristics of specimens which emit radiation. The authors give a brief survey of the methods of determining the average energies of spectra and the values of these quantities obtained up to the present time for various radioactive isotopes.Translated from Atomnaya Énergiya, Vol. 17, No. 1, pp. 9–17, July, 1964     

Calculating the transient temperature field in a reactor tube and the thermoelastic stresses in the fuel element cladding

Approximate analytic methods are given for calculating the transient temperature field in the fuel elements and the coolant temperatures at any point along the reactor tube, as well as the transient thermoelastic stresses in the cladding of a cylindrical fuel element. The coolant temperature at the input to the tube is constant, and the coolant undergoes no changes in state of aggregation. The approximate methods are illustrated by examples.Results are given, for comparison, of accurate calculations of the same examples made with a rapid calculating machine.List of symbols time - r; z coordinates (radius, distance along tube) - r₁; r₂ internal and external radii of fuel element cladding respectively - H total active length of fuel element - a₁; ₁;c _{1 1} coefficients of temperature conductivity, heat conductivity, specific heat capacity and specific gravity of fissionable material respectively - a₂; ₂; C_p2; ₂ cladding parameters - a; ; c_p; coolant parameters - mean cladding radius - f:f₂ cross-sectional area of tube for coolant and cladding respectively - w coolant velocity - coefficient of heat release to coolant - t (r, ); (); () fuel temperature, mean temperature over cross section of cladding, and coolant temperature at pointz. along tube respectively - qv() specific volume of coolant at pointz - values averaged overz - quantities at the initial instant of time - ₃ delay time - _n time required for coolant to go from z=0 to the point in question     

The distribution of ionization along a beam of γ-radiation and the determination of radiation dose with normal ionization chambers

It was established that the ionization effect, measured in normal ionization chambers for determining the dose in a region of -radiation, must be referred to a point in space, displaced by a distance of about from the center of the measuring electrode of the chamber towards the source. The corrections for displacement of the measuring volume for the -radiation of Cs¹³⁷ and Co⁶⁰, respectively, equal 0.996 and 0.992.     

Scattering of medium-energy neutrons

Conclusion A study of inelastic-scattering processes as a function of neutron energy and the number of nucleons in the nucleus has enabled us to observe and investigate the effects of the nuclear shells in inelastic scattering. Experimental data on the inelastic-scattering cross sections have been used to check the optical model of the nucleus with a diffuse edge [23].The values of nuclear-physical constants (_e,_tre, ) obtained from the measured angular distributions of elastically-scattered neutrons may be used for calculating multigroup constants [24] required for physical calculations of nuclear-power systems and biological protection (shielding). The experimental material on the angular distributions of elastically-scattered neutrons has enabled us to verify the applicability of the optical model for describing elastic-scattering processes at energies below 1 MeV.Part of the information obtained on the elastic- and inelastic-scattering cross sections and the angular distributions of elastically-scattered neutrons has been included in handbooks on nuclear-physics constants [25–27].Translated from Atomnaya Énergiya, Vol. 20, No. 1, pp. 8–17, January, 1966     

Measurement of the effective number of secondary neutrons from Pu239 in the incident neutron energy region from 7 to 30 ev

Measurements have been made of the energy dependence of the quantity (wherer is the average number of fast neutrons per fission event, _f is the fission cross section and _a is the absorption cross section) in Pu²³⁹ for the energy region ranging from 7 to 30 ev. A knowledge of this quantity is of interest both for practical reactor calculations and in the theory of nuclear fission. The measurements consist of counting the number of fast fission neutrons emitted from a sample of Pu²³⁹ with slow neutrons incident upon it. A higher resolving power in the neutron collector has made it possible to measure the ratio for the separate resonances. In this connection it is assumed thatv remains constant over the entire measurement region. From the data of the present work it is found that the fission widths of ten levels in Pu²³⁹ vary strongly from one to another and that they may be grouped.The authors are indebted to S. Ya. Nikitin for advice and continued interest in the present work.     

Helical magnetic configurations with minimum\bar B

A general consideration of magnetic configurations with helical symmetry and minimum is presented. An approximate analytic expression is obtained for the specific volume V'() in the neighborhood of the helical magnetic axis. Exact formulas for the specific volume V'() and the mean torsional angle of the lines of force i=2X'() are given in terms of single integrals. Graphs of V'() and X'() are plotted from numerical calculations of these integrals up to the separatix of the magnetic surfaces.Translated from Atomnaya Énergiya, Vol. 20, No. 5, pp. 396–401, May, 1966.     

Simulation of nuclear-fuel solvent-extraction reprocessing 7. Separation of macroscopic amounts of plutonium and uranium by displacement reextraction of plutonium in reprocessing fast-reactor fuel (section 1)

Conclusions These data have been obtained from simulating displacement reextraction in a system with two inputs (system for reprocessing a fast-reactor fuel), and they show that it is possible to obtain a uranium extract with not more than 100 g Pu/kg U in a counter current system with 18 stages to provide partial separation of the uranium and plutonium by reprocessing of an organic solution containing U⁺ Pu (10 1) with 64% saturation in the sum of the metals to produce reextract containing plutonium with U : Pu3 and over 99.99% extraction of the uranium; this requires 90 g/liter of uranium in the reextractant and the parameters n=2.06–2.00 ( =0.3 M); n=1.82–1.87 ( =0.5 M); n=1.61–1.78 ( =1.0 M).Full data obtained from the simulation are to be found in [5], from which one can extract the parameters of the working state of the extractor and other data on the separation of uranium and plutonium, e.g., for other specifications for the plutonium level in the uranium. The next part of the present study will be concerned with engineering solutions that can extend the range of conditions that provide the appropriate output parameters within specified ranges and thereby improve the reliability in operating the process in the optimal region.Translated from Atomnaya Énergiya, Vol. 47, No. 6, pp. 377–381, December, 1979.     

Using the method of moments to calculate the space-energy distribution of neutron density from flat and point sources in an infinite medium

A method is given for calculating the space-energy distribution of neutron densities from flat and point sources in an infinite medium.The neutron density (x, E) is sought in the form · To a large degree the form of the function K(x) is arbitrary; its selection is based on physical principles. From the 2N space moments of the function (x, E), 2N parameters a_i, b_i are found. The neutron density distribution is found in hydrogen and water. The calculations for water are compared with experimental data. A comparison with the accurate solution of Wick [1] in the case of retardation of neutrons by hydrogen shows that from four moments the suggested method can, with sufficient accuracy, find the spatial distribution of neutrons at distances up to 20 free path lengths.     

Analysis of the observed resonance-width distributions of U233 and Pu239

As a result of the strong fluctuations of fission and reduced neutron widths, a significant number of resonances occur with such a small reduced height 2gF_n ⁰/ that they will not be noticed experimentally. If the fraction of transmitted resonances is considerable, then this should lead to the following effects which might be observable in an experiment: 1) change of the distribution function of the reduced neutron and fission widths, which is particularly sharply manifested for _n ⁰/<_n ⁰> 1 and _f/<_f> 1; 2)appearance of correlation between the form of the neutron distribution b of fission channels; 3) appearance in the total cross section and fission cross section of a background which is approximately proportional to . All the effects mentioned are manifested for the U²³³ nucleus. For Pu²³⁹ this effect is smal! and the observed values are welI described by X² distributions.Translated from Atomnaya Énergiya, Vol. 17, No. 1, pp. 22–27, July, 1964     

Pulsational characteristics of two-cassette model of boiling-water reactor

Conclusions On a large-scale two-cassette model of the natural-circulation loop of a reactor with vertical dimensions and reduced hydraulic-drag coefficients of the basic loop elements that are close to the full-scale values, an experimental investigation has been conducted, with the following conclusions:With design parameters of the heat carrier, the specific thermal stress of the fuel elements, and the discrepancy coefficients of the pile power, the zone of hydrodynamic instability is characterized by the values ; liquidation of total-loop pulsations of the heat-carrier flow rate entails vapor condensation under the water level in the reactor; total liquidation of the pulsations requires, in addition, the introduction of disks at the input to each pile; the reduced hydraulic-drag coefficient _re of the disk must be no less than 0.8 of the sum of _re for the pile and the ITS.Translated from Atomnaya Énergiya, Vol. 69, No. 2, pp. 87–92, August, 1990.     

Methods for suppressing the longitudinal instability of a bunched beam with the help of landau damping

Conclusions The insertion of an additional accelerating system with multiplicity nq is desirable only in a synchrotron with a well-bunched beam, where the natural nonlinearity A ₀ ² is small.When the amplitude of the additional voltage is limited by the quantity nV_n/V_o1, there are two approximately equivalent schemes for switching on the harmonics nq (see Secs. 3 and 4), which permit obtaining an instability suppression factor of _max10/A _o ² with n_opt5/A_o.The efficiency of both schemes has been confirmed experimentally in ISR storage rings [1, 5], but there are no data for making quantitative comparisons of the experimental results with our calculations. At the same time switching on the harmonic n=2 in the PSB synchrotron without satisfying the condition (39) only increased the longitudinal instability of the beam [6].By raising significantly the amplitude of the additional voltage in the state of Sec. 3, which is equivalent to transferring to an acceleration multiplicity nq while keeping constant the number of bunches, it is possible to raise the instability suppression factor to _max 5/A _o ² with n_opt2.3/A_o[nV_n/V_o]^1/4.Translated from Atomnaya Énergiya, Vol. 62, No. 2, pp. 98–104, February, 1987.     

Analytic representation of the fission neutron spectra of235U and252Cf

Analytic representations of the spectra in two forms—in the form of a model spectrum and as a sum of nine model spectra , where α_i=4.2.1.333.1.0.0.8.0.4.0.2.0.05. and 0.01-are obtained on the basis of representative sets of integral cross sections for the fission neutron spectra of²³⁵U due to thermal neutrons and spontaneous fission spectra of²⁵²Cf.2 tables. 5 references. Translated from Atomnaya énergiya, Vol. 88, No. 4, pp. 299–303, April, 2000.     

The dynamics of nuclear power stations

This paper makes a comparison of the results of eXperimental and theoretical studies that have been carried out on the properties of the engineering model of the Beloyarskii atomic electric station under construction in the USSR, which uses nuclear superheating of the steam. It is shown that a number of the simplifying assumptions are correct which are often used in discussing the dynamics of nuclear power stations.The results of the studies may be used to make a theoretical analysis of the dynamic properties of several types of nuclear power installations, as well as in analyzing and synthesizing the optimum control system.Notation q() specific heat load, referred to length of segment, kcal/hour · m - f(x) distribution function of specific heat load along the length of segment - () heat transfer coefficient, including the thermal resistence of the fuel element, kcal/m² · hour · degree - t_f.e. (x, ) the current value of fuel element temperature, averaged over the corss section, degrees C - t(x, t) current value of coolant temperature, degrees C - p perimeter of fuel element, bathed by coolant, m - m weight of metal per unit length of fuel element kg/m - C_M heat capacity of metal and fuel element, kcal/kg · degree - i(x, ) current value of heat content of coolant, kcal/kg - specific gravity of coolant, kg/m³ - S live cross section of fuel element, m² - D(x, ) current value of flow of steam phase, kg/hour - G(x, ) current value of the flow of water phase, kg/hour - (x, ) current value of the fraction of the cross section occupied by steam - , specific gravity of water and steam at saturation temperature, kg/m² - i, i heat content of water and steam at saturation temperature, kcal/kg - t_S() saturation temperature, degrees C - P_i() pressure in i-th segment, kg/m² - l height, determining the level pressure between segments, m - g acceleration of gravity, m/hour² - w_i() coolant velocity at the i-th segment, m/hour - D_i() steam flow at the i-th segment of the superheating circuit, kg/hour - V_i volume of i-th segment of the superheating circuit, m³ - mean steam temperature at the i-th segment for the superheating circuit, degrees C - k₁,k₂,k₃,k₄ constant coefficients - N/N₀ relative power change in the evaporating channels, % - P_I, P_II pressure change in the first and second loops, atm - t_sps, t_fw change in temperature of superheated steam and feed water, respectively, degrees C Translated from Atomnaya Énergiya, Vol. 15, No. 2, pp. 115–120, August, 1963     

Use of perturbation theory in investigating the engineering and physical characteristics of nuclear power plants

Conclusions and recommendations Thus, the use of perturbation theory allows an economical, searchless, computation procedure to be constructed for the problem of parametric identification. The method may be extended to the case of a multidimensional model with nonlinear and nonsteady operators.At high noise levels of the experimental signal, a functional that is more conservative with respect to noise is preferable, in the form , for which perturbation theory is constructed analogously, under the condition P_j=1. Here also, z^e and y^e may be taken in the form of the results of statistical measurements R_zz and R_zy, i.e., the self- and mutual correlations of the noise functions of these signals, respectively.The perturbation formulas in Eqs. (6) and (9) are useful for the engineering diagnostics of NPP elements performed on the basis of an analysis of slow variations over time in the parametersa _i . In this case, identification by the given algorithm must be repeated periodically in the course of NPP running tests or use.Translated from Atomnaya Énergiya, Vol. 48, No. 4, pp. 238–242, April, 1980.