摘要:

AbstractThe temperature distribution in a cylindrical fuel rod has been calculated on the assumption that the flux distribution is expressible in the form of a series of Bessel functions, whether or not it actually obeys the simple diffusion equation. Variable thermal conductivity has been taken into account and a generalization of the classical solution has been obtained. A simplified design formula for a solid rod has been derived.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18722

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractA method was developed for computing the partial pressures of the various equilibrium vapor species existing above nonstoichiometric UO2 +x. The gas phase oxygen-to-uranium atom ratio was correlated with the oxygen-to-uranium ratio in the solid, which was known. The atom ratio, total pressures, and equilibrium constants of formation of each compound, sufficiently specify the system to allow the computation of the gas phase concentrations using multicomponent chemical equilibria computer techniques. The results agree with independent experimental data.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18723

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractThe differential elastic- and inelastic-scattering cross sections of10B,11B, natural Ge, and93Nb have been measured at incident neutron energies of 7.02 and 7.55 MeV for10B; 7.55 MeV for11B; 7.55 MeV for Ge; and 5.95 and 7.47 MeV for93Nb. The cross sections were measured with a neutron time-of-flight spectrometer relative to the cross section for neutron scattering from hydrogen.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18724

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractWe have obtained gamma-ray spectra for the reactions14N(n, n′γ)14N,14N(n,þγ)14C, and14N(n,αγ)11B for incident mean neutron energiesEn= 5.8, 6.4, 6.8, 7.4, 8.0, and 8.6 MeV. The gamma rays were detected using a coaxial Ge(Li) detector of 30 cm3active volume. The detector was placed at 55 and 90°with respect to the incident neutron direction, and was 77 cm from the sample; time-of-flight was used with the gamma-ray detector to discriminate against pulses due to neutrons and background gamma radiation. The sample was 100 g of Be3N2in the form of a right circular cylinder. Data were also obtained using a 75-g Be sample to provide an estimate of the background. The incident neutron beam was produced by bombarding a deuterium-filled gas cell with the pulsed deuteron beam of appropriate energy from the ORNL 6-MV Van de Graaff. The resulting neutron beam was monitored using a scintillation counter; a time-of-flight spectrum from this detector was recorded simultaneously with the gamma-ray data. These data have been studied to obtain absolute cross sections for production of gamma rays from14N for the incident neutron energies quoted above. The cross sections have been compared, where possible, with previously measured values with good agreement. However, there are several important differences with previous data and these are discussed. In particular, summing the partial cross sections yields a value for the total nonelastic cross section that is approximately half of the total nonelastic cross section obtained from the difference between the total cross section and the total elastic cross section.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18725

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractNucleon-meson cascade calculations have been carried out for 450-MeV protons incident on a variety of thick targets. The energy spectra of emitted neutrons and protons at specific angles are compared with experimental measurements.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18726

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractExpressions for the neutron flux at the exit of a cylindrical duct of radiusδand lengthl(withλ=δ2/l2), have been found by the use of the albedo concept and by the method of single-collision sources in the duct wall, based on monoenergetic integral transport theory. In contrast with other methods of solution, the isotropic area source of radiusδat the duct entrance is not approximated by a point source, and the numerical evaluation of integrals does not impose restrictions on the values ofλ. Calculation of the neutron flux at the duct exit is expedited by the use of the tables given, which are a function of the duct geometry and were generated from the numerical evaluation of the integrals that appear in the expressions for the flux.Comparison of the results as predicted by the formulas developed in this paper and those predicted by already existing formulas with the results of a stochastic neutron-transport code indicates that the formulas developed here are always in better agreement with the results of the code. For values ofλ<1, the formulas developed here differ by a maximum of±10%, while the existing formulas differ by a maximum of more than 100%.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18727

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractA method for calculation of proton dose in a receiver behind a combination electromagnetic and material shield is described. Dose calculations for a typical Van Allen proton spectrum and three solar-proton-event spectra are presented. In general, the electromagnetic shield stops protons below a certain threshold energy and reduces the number and energy of protons above this energy, and material shielding is more effective against these protons of reduced energy since proton stopping power increases with decreasing energy.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18728

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractIn this paper a multigroup method in finite monodimensional geometry is presented for neutron distribution calculation from a given source distribution. This method is extended to neutron importance function calculation for a given detector distribution.Furthermore, it is shown how truncating the calculation at whatever collision, it is possible to evaluate the“residual”neutron distribution by means of usual methods in diffusion or transport theory.An application is presented related to the generalized perturbation methods and the numerical solution of problems of general interest.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18729

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractA method of discrete representation of thermal-neutron spectra, especially suitable for U-Pu systems has been developed. The energy points and corresponding integration weights have been determined so as to provide accurate reaction rates in U-Pu lattices, the total number of points being considerably less than the necessary number of groups in multigroup treatment. Furthermore, a convenient method of scattering matrix construction has been proposed and the system of multipoint equations, formally identical to multigroup equations, has been derived.The proposed method has been tested by calculating thermal reaction rates and energy spectra in a pin cell and comparing with the group method. Some results are given in the present paper. The authors’experience is that in all practical cases 15 points are as good as 40 energy groups for calculating fuel reaction rates in the energy region below 2 eV.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18730

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor

摘要:

AbstractA series of experiments has been performed to study the diffusion of thermal neutrons in Al-H2O plate lattices. Although diffusion perpendicular to the plates could be described by an exponential function, thus defining a diffusion length, such was not the case for diffusion parallel to the plates. Various ancillary experiments support the conclusion that a discrete eigenvalue does not exist for parallel diffusion in such systems. This conclusion is in agreement with the theoretical predictions of Clancy, Durance, and McCulloch, and of Williams.

ISSN:0029-5639    

DOI:10.13182/NSE69-A18731

出版商:Taylor&Francis    

年代:1969

数据来源: Taylor