摘要:

AbstractTests were conducted to evaluate methods of simulating on a small scale the effect of nuclear reactor“runaway”on a containment shell surrounding the reactor. Test results from air-filled core vessels were compared with existing blast data from bare chemical explosives and also with Brode's theoretical analysis of spherical blast waves to find the applicability of the test data to the concept of equivalent weight of bare charge.Additional tests were conducted with explosive charges bursting water-filled simulated reactor core vessels. These test results showed that shock waves were formed in air close to bursting vessels, and that the pressure-time histories differed considerably from the“classical”free air blast waves from bare charges. The concept of equivalent weight would therefore not apply to the latter experiments.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25703

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractAn improved theoretical basis is presented for the interpretation of the pulsed-neutron technique for measuring thermal-neutron absorption cross sections and transport parameters. A procedure is given for the exact solution of the Fourier-transformed, multivelocity transport equation in an infinite medium. The objective is the calculation of the decay constant of the thermalized neutron flux following an initial pulse of fast neutrons. The method used is an expansion of the decay constant and neutron spectrum in a power series in the Fourier-transform variable. The procedure is first illustrated for the case of isotropic scattering and then generalized to anistropic scattering by using the spherical harmonics expansion.The results are given in terms of integral equations whose solution involves a knowledge of the energy-transfer cross sections between thermal neutrons and the moderating material. The approach employed is to extract the maximum amount of information which is independent of these cross sections and to derive explicitly the equations involving them. It is necessary to solve these equations in order to obtain more accurate information.Finally, the relation of the infinite medium Fourier transform variable to the geometric buckling of a finite sample is discussed. It is noted that the conventional interpretation of the experiments in terms of the diffusion coefficient and diffusion cooling coefficient requires the assignment of an equivalent infinite medium buckling to each finite sample measured. The discussion in the present paper makes plausible the validity of this procedure.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25704

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractThe Spinrad three-group theory of the fast effect is formulated. Recipes are presented for determining the necessary cross sections directly from fundamental data and three-group cross sections for various materials are tabulated. A comparison is made between the three-group theory and one-group theory with respect to the calculation ofR, the ratio of fast-to-thermal fissions, and it is found that the three-group theory appears to give better agreement with experiments. The three-group values ofЄ–1 are about 20% higher than those calculated from the one-group formula.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25705

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractNeutron fluxes and currents in the vicinity of control rods inside reactors are calculated in age-diffusion theory, using a control rod in the form of an infinite plane slab and approximating its transparency by a simple analytical expression. The results are compared with a two-group calculation for the same geometry and indicate the degree of accuracy of the latter method. The comparison is made for epithermal neutron energies only, and shows that in this region, two-group theory is applicable for a calculation of the number of neutrons absorbed by the control rod with a fair accuracy.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25706

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractIt is shown that an analogy exists between the neutron flux as predicted by single-group neutron diffusion theory and the axial component of the electric field intensity in a field excited as a plane transverse-magnetic wave in a cylindrical cavity. The buckling of a homogeneous bare core could be determined using simple microwave devices to an accuracy on the same order as the uncertainty of the cavity dimensions. Experimental techniques are described for measuring control rod worth for fully extended cylindrical control rods of arbitrary cross section and illustrative solutions are shown for circular, hexagonal, square, cruciform,“Y”and sheet cross sections located at the center and at radial positions in a circular core. A method is described for predicting the flux distribution in the core region and experimental examples are shown.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25707

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractElastic and one-phonon inelastic scattering cross sections of neutrons in graphite have been calculated for neutron energy less than 2000k0. For the lattice vibrations in graphite, the model proposed by Krumhansl and Brooks has been used. We have also calculated the mean energy loss per collision and the mean logarithmic energy decrement. Assuming that close to equilibrium the neutron distribution remains Maxwellian, the time variation of the temperature of this distribution has been calculated. The slowing down relaxation time near equilibrium comes out to nearly 170µsec, which compares well with the experimental value of 185±45µsec.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25708

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA study and statistical analysis has been performed on available burnout heat-flux data for vertical upflow of water in uniformly heated rectangular channels at 2000 psia. Two correlating equations were developed with the fluid mass velocity and enthalpy at the burnout location as the two independent variables. It was not found necessary to include the channel length-to-thickness ratio as a third independent variable. The range of variables studied are: 540 to 1000 Btu/lb burnout enthalpy and 0.2×106to 5×106lb/hr-ft2mass velocity. It is shown that the burnout heat-flux decreases as mass velocity increases for a constant burnout enthalpy in the quality range. Also, a comparison of the developed correlations based upon data for uniformly-heated channels was made with 25 burnout data points for channels having a cosine-shaped axial heat-flux distribution. The cosine data fall on the average of about thirty percent below the burnout heat-flux values for uniformly heated channels under the same coolant conditions at the burnout location.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25709

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractMethods for determining an effective resonance integral from available resonance parameter data are examined and applied to lumped systems where the absorber is U238. Agreement with experiment is satisfactory in view of an uncertainty of about 10% introduced by probable errors of the parameter data. The empirical formulais expected to represent the geometric behavior ofIbetter than other two-parameter formulas when applied to a variety of fuel element compositions. For uranium metal the formula is virtually indistinguishable from the formula of Gurevich and Pomeranchouk:Quantitative results describing the temperature and energy dependence of resonance captures are also given.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25710

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA previous paper of the author, in which theorems are given for the estimation of average collision probabilities for convex solids of irregular shape by comparison with solids for which the average collision probability is known, is extended.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25711

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor

摘要:

AbstractA Monte Carlo calculation of the spatial distribution of resonance neutron capture across a O.387-in. diameter gold rod is compared with the corresponding measured distribution, obtained by activating small gold foils stacked across a diameter of a cadmium covered gold rod. The difference between the Monte Carlo calculation and the measurement is attributed to relatively unshielded capture at energies above 250 ev, the starting energy for neutrons in the Monte Carlo calculation.

ISSN:0029-5639    

DOI:10.13182/NSE60-A25712

出版商:Taylor&Francis    

年代:1960

数据来源: Taylor