摘要:

AbstractThe elastic-plastic deformation of a long cylinder subjected to uniform heat generationQis considered using Tresca’s yield function and an associated flow rule for perfectly plastic material. The ends of the cylinder are assumed to be free and all elastic and thermal parameters temperature-independent. We suppose that the outer surface is insulated and that heat is removed from the inner surface. IfQis allowed to increase at a sufficiently slow rate so that time effects can be neglected, then yielding commences on the inner surface. For the Poisson ratiov= 0.3, immediately after initiation of yield two inner plastic regions and an elastic region form. One of the plastic regions corresponds to a singular regime of the Tresca yield function. The interfaces of the regions propagate outward asQis increased. For outer to inner cylinder radius ratio equal to 5 it was found that, forQabout 4 times the value giving the initial plastic yielding, a third plastic region formed in the interior of the elastic region. The work was stopped at this point. The equations involved were solved numerically.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28876

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThe stationary velocity-dependent transport equation for an infinite homogeneous source-free medium is solved by expanding the solution into a power series of the eigenvaluesκ= 1/L. The integral equations, obtained by equating terms with the sameκ0m, have been solved numerically on the IBM 704 computer using the iteration procedure. The monatomic gaseous model for the scattering process has been used assuming scattering cross section to be independent of the relative velocity and the absorption cross section to follow the 1/vlaw.A general expression for the diffusion coefficient in the absorbing medium has been obtained whereas the diffusion lengthLis obtained as the only positive real root of an algebraic equation whose order depends on the degree of the approximation.A comparison between the calculated and measured values of the diffusion length in poisoned water shows that water can be described roughly as a monatomic gas withA= 1.9 andls(∞) = 0.40 cm. An empirical formula for the effective temperature of the neutron velocity distribution is evaluated.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28877

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE63-A28878

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractA preliminary measurement of the Doppler effect in metallic thorium has been made in a fast neutron energy spectrum. The effect has been investigated up to slug temperatures of 500°C by an oscillator technique in which sensitivities on the order of 2×10-8Δk/kcan be attained with reasonable ease. The observed reactivity changes appear at this time to result largely from Doppler broadening of the resonances. This conclusion is supported by the fact that several, well-recognized correction terms have been found to be unimportant under the present circumstances. Based on a straight-line approximation to the measured points, the value of (1/ρ)(dρ/dT) was found to be 7.18×10-5/°C.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28879

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractA summary is presented of the available physical property data on 94 molten fluoride salt mixtures which have been evaluated for utilization as high temperature fluid fuels and reactor coolants. The specific physical properties which were either measured or calculated include density, heat capacity, heat of fusion, enthalpy, viscosity, thermal conductivity, and electrical conductivity. The experimental techniques and apparatus used in making the measurements are described, and the probable experimental errors are given. Some of the problems and potentialities of reactor systems using molten salt fuels and coolants are also briefly discussed.

ISSN:0029-5639    

DOI:10.13182/NSE63-5

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThe time dependence of neutron transport is investigated using various approximations in moderating media. Transients and asymptotic solutions are clearly distinguished. It is shown that there is no real asymptotic eigenvalue for large bucklings. Transients are classified and shown to arise from a mismatch of the initial flux with the asymptotic distribution in energy or in angle or from a finite source. These features are demonstrated by means of analytic solutions of pulsed problems using low order approximations. The demonstrations are also extended to arbitraryP-Lapproximations (but not time-dependent diffusion theory) for an arbitrary number of energy groups.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28881

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractIn a single-species system with similarly varying cross sections, it is commonly assumed that the collision densityF(u) has the asymptotic form kemu, wheremsatisfies the equation(1−α) (1 +m)−c(1−α1+m) = 0.This is equivalent to assuming that the pole with greatest real part of the Laplace transform ofF(u) occurs at the real rootm(≠−1) of the last equation. No proof of this assumption appears to have been given hitherto in the literature, so it is now shown, by the use of certain results in the theory of transcendental equations, that ifzis any complex root of the equation, then irrespective of the values ofαandc,Rez

ISSN:0029-5639    

DOI:10.13182/NSE63-A28882

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractMeasurements of the diffusion parameters of heavy water were made using a 1 Mev Van de Graaff accelerator utilizing the Be9(d, n) reaction under pulsed operation. The measurements were made at temperatures of 10°, 20°, 31°, 40°, and 50°C for buckling values ranging from 0.063 cm−2to 0.100 cm−2. The decay of the neutron density was measured by a BF3counter, located under the moderator container, in conjunction with a 26-channel time analyzer. The meanlife for each buckling was computed using Peierls’method; and values of the diffusion parameters were computed by the method of least squares. The value of the diffusion constant, (2.00±0.04)×105cm2/sec at 10°C, agreed within the limits of experimental error with that found by Raievski and Horowitz, who used the modulated source method. The coefficient of the B4term, usually referred to as the diffusion cooling coefficient, was found to be (3.72±0.50)×105cm4/sec as compared with (3.5±0.8)×105cm4/sec as reported by Sjöstrand in 1959.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28883

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractThe variational formalism is used to derive from the monoenergetic Boltzmann equation a diffusion theory with the asymptotic transport diffusion coefficient. By considering an interface between two media as the limiting case of a medium with continuously varying properties, the boundary conditions are found to be continuity of current and a specified discontinuity in the scalar flux. The variational formalism gives the linear extrapolation distance for a pure scatterer accurate to within one-half percent. Numerical comparisons with classical (P-1) diffusion theory for a cell calculation indicate that the variational diffusion theory is significantly more accurate; the accuracy appears to be comparable with that of theP-3 method.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28884

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor

摘要:

AbstractIncreasing industrial, military, and space requirements for certain fission products places emphasis on new and large-scale methods for their recovery from reactor process waste liquors. With recent developments of new organic extractants for these fission products, solvent extraction offers a versatile alternate technology to ion-exchange, precipitation, and crystallization technologies heretofore used for small-scale recoveries.A process flowsheet has been developed for recovery of strontium and mixed rare earths from adjusted Purex 1WW using di(2-ethylhexyl)phosphoric acid (D2EHPA). After addition of tartrate to complex iron and caustic to adjust the pH to 6, strontium and rare earths are coextracted, then co-stripped with HNO3in the first cycle. In additional D2EHPA extraction cycles, they are isolated as concentrated fractions. The mixed rare earths from this process can be treated by TBP extraction to separate the individual rare earth elements of which promethium and cerium are of greatest interest. Zirconium-niobium also may be recovered with D2EHPA from acidic waste liquors.An amine pretreatment extraction process has been developed which removes nitric acid, iron sulfate, zirconium-niobium, and ruthenium from waste solutions to furnish a feed liquor more amenable to subsequent fission product recovery processes. The separate recovery of ruthenium, zirconium-niobium, and rare earths may also be possible by amine extraction.A process has been developed for recovery of cesium from alkaline waste solutions using substituted phenols. These compounds are selective extractants for cesium, giving high decontamination from other fission products and sodium. They are readily stripped with dilute HNO3.Previous studies have also outlined methods for recovering neptunium, plutonium, and technetium with solvents similar to those described here. When appropriately combined, these developments offer a versatile integrated solvent extraction flowsheet for recovery of all important fission products and other components from waste liquors.

ISSN:0029-5639    

DOI:10.13182/NSE63-A28885

出版商:Taylor&Francis    

年代:1963

数据来源: Taylor