Can the Inertial Alfvén Wave Become an Electrostatic Mode in the Limit 1 ≪ λ2 e k 2?

Analytical calculations are presented to clarify that the inertial Alfvén wave cannot become an electrostatic mode in the limit ² _e k ² (where _e is the electron skin depth and k is the component of the wave vector in perpendicular direction to the external magnetic field).     

Ignition in a tokamak reactor with INTOR-like parameters

The requirements for ignition in a tokamak reactor with INTOR-like parameters were studied using a one-dimensional transport code. With empirical electron energy diffusivity _e , ignition was obtained with 60–75 MW of neutral beam injection at a volume average pressure ratio =4–5% under a variety of conditions. Changing _e gave ignition at the same if the plasma minor radius varied asa _e ^1/2 . The maximum impurity concentration which allows ignition was found to be comparable to that for the much simpler case of a homogeneous plasma with radiative losses only. In long pulse simulations with efficient helium pumping, the maximum toroidal field ripple which allowed ignition was 2.0% (peak-to-peak) at the plasma edge. Ignition was maintained with over 99% recycling of helium ash using 5% less than maximum ripple.     

Methods for preparing ions of short-lived isotopes

Conclusions A source with thermal ionization in a cavity is extremely convenient for obtaining ion beams with an ultralow quantity of the starting material. Its efficiency with ionization potentials of the starting atoms V_i<6 eV is equal to 100% and drops to 1% for V_i=8 eV [7]. This makes it possible to use it in the study or more than two-thirds of the periodic system of elements, including the actinides. Thus for 10¹² uranium and plutonium atoms ^*9% and 50%, respectively; for 10⁶ curium atoms ^*70%; and, for 10⁵ californium atoms ^*37% [13]. It was shown in [14] that this source can be successfully used in mass spectroscopy to analyze trace quantities of different elements in the solid phase. With its help yttrium isotopes with _1/2=0.4 sec were detected in [16].This source is now widely used in our country, where with its help tens of new isotopes have been discovered [15, 17], and abroad (for example, [16]). The source is effective for short-lived isotopes with _i/_1/2<10 and V_i<7 eV. To study isotopes with _i/_1/2<10 and V_i>7 eV but with _i/_1/2>10 it is desirable to develop sources with thermal and photoionization in the cavity. For elements whose atoms have a long residence time on the surface, these sources, just as the gas-discharge sources, are inefficient. Means must be developed for raising the rate of desorption of the indicated atoms from the surface within the framework of the techniques examined here.Translated from Atomnaya Énergiya, Vol. 60, No. 2, pp. 114–119, February, 1986.     

Heat transfer in a region of thermal stabilization in the turbulent flow of liquid metals in a tube

In the work described here, local heat-transfer coefficients were determined for turbulent flows of liquid metals (Pr 0.02) in a region of thermal stabilization ( _t equal to 5, 10, 15 d) for Reynolds numbers Re = 10⁴-2·10⁵. The determinations were made by two methods: by the measurement and analysis of temperature profiles in the flow without taking into account the thermal contact resistance, and by directly measuring the temperature changes in the wall, taking into account the thermal contact resistance. Hydrodynamic stabilization of the flow was maintained during the experiments ( _t 30 d).     

Cross section for the formation of gamma-quanta during the interaction of fast neutrons with carbon,lead, and rhenium nuclei

Conclusions The values obtained for the cross sections for formation of -lines (E=4.44 MeV) in carbon agree with the data obtained by other researchers, within experimental error.The results of measurements for lead agree qualitatively with our understanding of the deexcitation of levels in the reaction (n, n) for E_n<4 MeV.The energy distribution of -quanta for rhenium decreases smoothly with increasing E. No irregularities, related to separate intense -transitions in the excited nucleus, are noticeable.Translated from Atomnaya Énergiya, Vol. 49, No. 4, pp. 236–239, October, 1980.     

The effect of neutron irradiation on the internal friction of zinc monocrystals and polycrystals

By an investigation of the effect of neutron irradiation on the internal friction of zinc polycrystals and monocrystals, we determined the value of the critical stress amplitude _cr before and after irradiation.It was shown that the value of _cr, which may be related to the beginning of the motion of dislocations, increases as a result of irradiation. The increase of _cr in irradiated zinc is explained by the fact that the dislocations are held fixed as a result of interaction with point defects.In addition, we studied the effects of the orientation of the basal plane (0001) with respect to the longitudinal axis of the zinc monocrystal specimen on internal friction and on _cr. The results of the investigations of the effect of orientation on internal friction and on _cr are compared with well-known representations of slippage obtained from static studies of monocrystals in tension along one axis.The authors express their gratitude to S. T. Konobeevskii for his comments on the results of the work.     

Analysis of the composition of a mixture of249Bk+249Cf on the basis of x rays

Conclusion The results of the study enable us to conclude the following: the decay of²⁴⁹Bk is accompanied by an L series of x rays from the daughter product Cf. The yield of this radiation is low: (L+L+ L) 10^–4 ( disintegration)^–1, but because of the high specific activity of²⁴⁹Bk, 1 g of this isotope emits 3.7·10⁵ x-ray quanta per minute. This enables us to detect a fairly small amount of Bk (0.01 g) on the basis of x rays in a period of 5–10 min. The rapid accumulation of the daughter product²⁴⁹Cf does not interfere with the determination of the²⁴⁹Bk on the basis of x rays. Even when the mixture contains equal numbers of Bk and Cf nuclei, the ratio of the L lines corresponding to them is 0.46. Therefore the composition of a mixture of²⁴⁹Bk+²⁴⁹Cf can be determined on the basis of x rays over broad ranges of variation of the relative concentrations of Bk+Cf, roughly from 0.03 to 80. It is important to note that for relative measurements it is not necessary to prepare special specimens, since x rays with energies of 15–20 keV are not strongly absorbed in the solution and in the walls of the chemical vessel.Translated from Atomnaya Énergiya, Vol. 48, No. 2, pp. 106–108, February, 1980.     

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 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     

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.     

Immobilization of Radionuclides in Irradiated Reactor-Graphite Blocks

The immobilization of radionuclides in samples of GR-280 reactor graphite by the fixative atomik is described. A graphite block extracted from RBMK masonry after 17 years of operation is used for the investigations.The investigations showed that the strength of the fixative samples increases only with irradiation doses above 15000 Mrad. The radiation–chemical yield of gaseous products of radiolysis from samples of the fixative under irradiation in vacuum is 12·10^–10 cm³/(g·rad). , , and -emitting nuclides are leached from the samples of irradiated graphite; this process proceeds continually. When the irradiated graphite samples are permeated with the fixative atomik, no release of radionuclides is observed at 20°C for 2 yr.     

Paramagnetic effect under the influence of high-frequency pressure and electron paramagnetic resonance in plasma

The interaction of uhf fields ( = 2· 10¹⁰ sec^–1) in a space resonator containing dense plasma (n 10¹³ – 10¹⁴ cm^–3) in a steady magnetic field was studied experimentally. Under the influence ofhf pressure a paramagnetic current arises in the plasma; the associated effect of an increase in the static magnetic field inside the plasma agrees closely with the calculated relation.For _H/ = 0.5 paramagnetic resonance of the electrons takes place; this leads to a sharp rise in plasma pressure p₀, up to =8p₀/H₀ ²0.2.Translated from Atomnaya Énergiya, Vol. 20, No. 5, pp. 401–407, May, 1966.     

DELSY Project – Dubna Electron Synchrotron

The DELSY (Dubna electron synchrotron) accelerator complex, including a 1.2-GeV electron storage ring, is under construction at JINR. This complex is a high-luminosity source of synchrotron radiation. It contains a linear accelerator-injector and a family of free-electron lasers operating in a wide spectral range from infrared radiation ( 100 m) to high-energy x-rays ( 0 keV). The DELSY source will make it possible to expand current research performed at JINR on the condensed-state and atomic physics, biology and medicine, crystallography and x-ray spectroscopy, nuclear physics, and metrology. The project is being implemented in three phases.     

Lawson concepts and criticality in DT fusion reactors

The original Lawson concepts (amplification factorR and parametern as well as their applications in DT reactors are discussed in two cases: the ignition regime and the subignition regime in a self-sufficient plant. The modified Lawson factor or internal amplification factorR (a function of alpha power) is proposed as a means to measure the ignition level reached by the plasma, in a more precise way than that given by the collective parameter (nkT). The self-sufficiency factor () is proposed as a means to measure the plant self-sufficiency, being more significant than the traditionalQ factor. It is stated that the ignition regime (R =1) is equivalent to a critical state (energy equilibrium); then, the corresponding critical mass concept is proposed. The analysis of theR relationship with temperature (kT), (n), and recirculating factor () gives the conditions for the reactor to reach ignition or for the plant to reach self-sufficiency; it also shows that an approach to ignition is not improved by heating from 50 to 100 KeV.     

Resonance scattering of γ-rays in Mg24

Resonance scattering of -rays With energies E₁=1.38 Mev, corresponding to the transition to the ground state in Mg²⁴. have been observed in metallic magnesium. The energy given off by the -ray (E₁=1.38 Mev) in emission and collision with the nucleus, is compensated for by the energy obtained due to recoil associated with the emission of the preceding -ray with an energy E₂ = 2.76 Mev. Using a fast coincidence method and amplitude discrimination, coincidences were recorded between the -rays with energies E₁=1.38 Mev and E₂=2.76 Mev. Scattercrs of magnesium and aluminum were alternately placed in the path of the 1.38 Mev -rays. The source was radioactive Na²⁴ in a water solution of NaOH. At an angle of 120 ° between the -rays a strong attenuatlon of the 1.38 Mev -rays was observed; this is attributed to resonance scattering. When the angle between the -rays was varied by 5 °. the strong attenuation of the flux disappeared. The width of the level at 1.38 Mev in Mg²⁴ has been estimated at > 1.6· in^–4 Mev.     

Containment of plasma in a trap with combined magnetic field

The containing properties of an adiabatic trap with a magnetic field increasing in the longitudinal and radial directions are investigated. This field is obtained from a combination of the ordinary mirror field configuration (main field H0) and the field of a system of current-carrying conductors laid parallel to the axis of the trap (stabilizing field H). The conductors are placed uniformly in azimuth around the side walls. The trap is filled with plasma of density n10⁹–10¹⁰ cm^–3 and proton energy T_i5eV (T_e20 eV). The plasma lifetime is measured as a function of H. and the neutral gas pressure. From the results obtained, it is concluded that such combined fields ensure stable containment of the plasma, unbroken by magnetohydrodynamic instabilities [at any rate for = nI/(H²/8) 10^–4]. The stabilization of the instability is confirmed by analysis of the plasma oscillations for various values of H. The disintegration of the plasma is determined by the charge exchange of fast ions in the residual gas; the maximum containment time which can be achieved is 0.06 sec for p = 7.10^–9mmHg. A qualitative picture of the plasma density over the radius of the trap is obtained.Translated from Atomnaya Énergiya, Vol. 17, No. 5, pp. 366–375, November, 1964     

Identification tables for use in the analysis of α and β activities

In order to facilitate the identification of activities being subjected to analysis, tables are compiled according to data published prior to 1958 containing the distribution of all known - and -radioactive isotopes as a function of their T_1/2, end-point energies of their -spectra, and -particle energies. The tables make it possible to establish a group of isotopes with a previously established T_1/2 and energies of radioactive emission. In a number of cases, the use of a scheme involving the radioactive decay chain may also prove expedient in the identification of activities.We consider it our duty to express our gratitude to Yu. A. Zysin for a discussion and his advice.     

Corrections for multiple scattering in spherical and circular geometries

In this paper a method is considered of introducing corrections for multiple scattering into the results of measurements of angular distributions of elastically scattered neutrons. It is assumed that the mean path of the neutron in the sample in which scattering takes place is comparable with the neutron free path.In the first part, using direct calculation of the integrals, we find the probability for double scattering and estimate the probabilities for triple and higher-order scattering for a sphere and for a ring of circular and rectangular cross section in the case of isotropic neutron scattering. In the case of anisotropic neutron scattering, at neutron energies of the order of several million electron volts the cross section may be given as a sum () = ₁ () + ₂ (), where ₁() is the forward peak and ₂() is more or less isotropic. Using this representation all elastic scattering events may be provisionally divided into two groups while all double scattering events can be divided into four groups. The probabilities of double scattering for all four are calculated on the basis of results obtained for isotropic scattering. Triple and higher-order scattering are evaluated in similar fashion.     

Investigation of the Effect of Radiation and High-Temperature Treatment on the x-Ray Luminescence of Quartz Glasses

The x-ray luminescence of KI, KV, and KU-1 quartz glasses, irradiated with and n– radiation in the dose range 10²–10⁷ Gy and neutron fluence range 10¹⁵–10¹⁷ cm^–2 and subjected to high-temperature annealing in air at 450 and 900°C is investigated. It is shown that the spectra of the nonirradiated and the and n– irradiated glasses of the first two types are a superposition of bands with _max = 410 and 460 nm, which are due to an impurity center initially present in the glasses (_max = 410 nm) and the initial and radiation-generated with dose 10⁶ Gy and fluence 10¹⁶ cm^–2 E' centers (_max = 460 nm). X-Ray luminescence is not observed in nonirradiated KU-1 glasses; a band with _max = 460–470 nm, due to radiation-generated E' centers, appears in the spectra of and n– irradiated glasses. As the radiation dose and the neutron fluence increase, the number of impurity centers decreases and the number of E' centers increases. It is established that the 410 nm band is due to the component of the n– radiation. High-temperature annealing in air at 900°C induces in the spectra new bands with _max = 470 and 520–540 nm, which are believed to be due to interstitial defects of the type O^– and O₂ ^–, formed when oxygen from air diffuses into the glass and localizes in interstices. 6 figures, 7 references.     

Thermodynamics of the extraction equilibria for uranyl nitrate

The fundamental thermodynamic principles of the extraction equilibria for uranyl nitrate are examined. The equilibrium characteristics are associated with considerable nonideality of the aqueous phase — a strong electrolyte, and the organic phase -a practically undissociated nonelectrolyte.It is shown that, at ionic strengths of up to 10, ion association in the aqueous phase does not significantly influence the distribution of uranyl nitrate. It is noted that in most instances the solutions of uranyl nitrate in the organic phase are close to regular solutions, and therefore there is no need to postulate solvation in the organic phase for interpretation of the equilibria. The effect of a salting out agent on the activity coefficient at constant concentrationx of the latter is examined. It is shown that the relationship between _{(x, m)} and the concentration of the salting out agentm is determined by the ratio of the Harned coefficient for the salting out agent to a quantity _e, characteristic for uranyl nitrate: log _{(x, m)}/_{(x, o)} = 2(_U— _s)J_s, where _(x,o) is the activity coefficient of uranyl nutrate in the absence of a salting out agent, and J_s is the ionic strength of the salting out agent. If _s < _U, then addition of salting out agent raises , and conversely; when _s = = _U (ammonium nitrate), is practically independent of the concentration of salting out agent. The value of _s decreases and the salting out agent becomes more effective with increasing number of molecules hydrating the cation. Equivalents of the salting out agents differ from chemical equivalents by activity coefficient corrections, and they can be only approximately constant.The variation of the distribution coefficient with the degree of dilution or saturation of tributyl phosphate in extraction by mixed solvents, and the conditions of mutual displacement of the substances being extracted from the organic phase are examined. The role of nonideality of tributyl phosphate — dilutent solutions in the extraction of uranyl nitrate is demonstrated.The parameters which determine the distribution of uranyl nitrate when different solvents and salting out agents are used are the distribution constantk, the nonideality constant of the solvent , and _s. The most important parameter is the distribution constantk, which varies several 1000-fold for different solvents. It is shown that the distribution curves have three characteristic regions, the extents of which depend on the value ofk and the nonideality constant of the solvent .