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.     

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 .     

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     

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.     

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.     

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.     

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     

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.     

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     

Accelerators with similar orbits

We obtain the conditions that must be satisfied by a magnetic system in order that the frequencies of radial and vertical betatron oscillations be independent of the particle momenta (in this case the orbits are called dynamically similar). In such systems mere should in principle be no excitation of betatron oscillations associated with synchrotron oscillations and other phenomena. A magnetic field with n₀ = const produces both geometric and dynamic similarity of the orbit. In weak-focusing accelerators with segments (race tracks) and in strong-focusing proton synchrotrons, the orbits are not dynamically similar. In order to obtain this kind of similarity in the first case, in addition to n₀ = const it is necessary that the magnet sectors have a common center. Different types of annular synchrocyclotrons are considered. In the first type the centers of neighboring magnet sectors are located on different sides of the doughnut and in the second type at the same point (at the center of the accelerator). In the second type the orbits are dynamically similar, unlike those of the first. It is shown mat it is possible to design an annular synchrocyclotron in which the particles can move with stability simultaneously in both directions within the doughnut.     

Neutron diffusion in a plane uranium-water lattice

The diffusion lengths for a plane uranium-water lattice are calculated for thermal-neutron diffusion parallel (L) and perpendicular (L) to the layers. The calculation of L is carried out in the diffusion approximation but can be used without the introduction of nondiffusion corrections since it is correct in the limiting cases (thick and thin layers). The calculation of L is carried out both in the diffusion and nondiffusion approximation: in the latter case, however, it is assumed that the absorption is small. In the case of thick layers, the ratio may reach 1.9. It is shown that if a uranium-aluminum alloy is used the anisotropy becomes still larger. As the layer thickness is reduced the anisotropy is reduced and finally vanishes.     

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     

Problem of the iodine method of purification of zirconium

A method is proposed for the determination of the equilibrium constantsk and k' for the reactions Zr+2I₂–ZrI₄=0 and 2I–I₂=0, which is based on the measurement of the amount of iodine or zirconium liberated in the decomposition of zirconium tetraiodide on a heated surface in the process of establishing equilibrium. The decomposition of the tetraiodide was carried out at 900–1600C on a tungsten filament. The temperature distribution between filament and vessel walls was neglected.The dependence of the sum of atomic and molecular iodine pressures on zirconium tetraiodide pressure was determined at 1430C, and on temperature for 50 mm Hg. The values of kk'² 35 (mm Hg)³ at 1430C and k0.07 mm Hg at 400C, found from the results, differ substantially from known thermodynamic data, but give good agreement between the authors' formula [1] and experimental results on the iodide process of zirconium purification.     

On M1-transitions from highly excited states

This article is concerned with the probabilities of Mi-transitions from states created by the capture of thermal neutrons for even-odd and odd-odd emitting nuclei with A from 20 to 60. In the single-particle model, such transitions are forbidden with respect tol. A comparison with the probabilities of E1-transistions shows that in even-odd nuclei, the probabilities of forbidden Mi-transitions which we observed, did not differ much from the probabilities ofl-allowed M1-transitions for lighter nuclei.In the case of odd-odd nuclei, certain M1-transitions are characterized by a large number of quanta per single neutron capture and a large value of      

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.     

Impact of Solid Breeder Materials on Tritium Breeding in a Hybrid Reactor

Tritium breeding ratio (TBR) is one of the important parameters in design of a Deuterium–Tritium (DT) driven hybrid reactor. Therefore, selection of tritium breeder materials to be used in the blanket is very crucial. In this study, tritium breeding potential of the solid breeders, namely, or in a (DT) fusion driven hybrid reactor fuelled with or was investigated. For this purpose in addition to these solid breeders, different types of liquid breeders, namely natural lithium, Flibe, Flinabe and were used to examine the tritium breeding behavior of liquid–solid breeder couple combinations. Numerical calculations were carried out by using Scale 4.3. According to numerical results, the blanket with fuel using natural lithium as coolant and as solid breeder had the highest TBR value.     

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.     

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