摘要:

The energy-dependent thermal diffusion equation is considered in a region free of external sources. Two cases of experimental interest are calculated. The first of these is the steady-state condition where an eigenvalue problem for the thermal diffusion length is obtained. The associated eigenfunction is the neutron spectrum. The second case, which is mathematically identical to the first, is the exponential decay in time of the thermal flux in a pulsed source experiment. The neutron leakage is assumed to be describable by a single eigenvalue for the buckling. In this case the eigenvalue is the decay constant of the flux.When the ratio of absorption cross section to transport mean free path decreases with energy in the thermal region, the first case will give a“diffusion hardening,”and the second case a“diffusion cooling”of the neutron spectrum compared to a Maxwellian distribution at the moderator temperature. These effects are investigated quantitatively for the model of a heavy gaseous moderator.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25440

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An experimental evaluation has been made of the Po-Be fast neutron absorbed dose albedos for concrete, water, and aluminum. By assuming neutrons are scattered isotropically in the center of mass system, a good fit to Plesset’s albedo theory was obtained. The values for the albedos were found to be 0.32 for aluminum and concrete, and 0.092 for water.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25441

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

Three corrosion resistant uranium base alloys were corrosion-tested in high temperature water: U-5% Zr-1½% Nb, U-3% Nb-0.5% Sn, and U-3.8% Si. Only the U-3.8% Si alloy retained any degree of corrosion resistance after burnups in excess of 0.1 at. %. Low burnup did not adversely affect the corrosion resistance of the diffusion bond between U-2% Zr alloy and its Zircalloy-2 cladding.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25442

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An explicit form for the function representing the probability that a neutron with velocity v′shall be scattered into an element of volume in velocity spaced3vabout v, by elastic collisions with atoms of arbitrary mass numberAin a Maxwell-Boltzmann distribution characterized by a temperatureT, is derived. Analytical representations of this probability are presented for scattering cross sections which are either independent of relative speed or exhibit a Gaussian dependence. The scattering probability resulting from the former assumption is examined in some detail, and then employed in a calculation of the mean energy change per collision.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25443

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

An expression for the charge life of a reactor is derived in terms of a model which assumes that enough uniformly distributed poison is always present to keep the reactor critical with control rods withdrawn. The burnout distribution is assumed to be constant and to be the same as at the end of the run, or to follow the calculated thermal flux distribution. Two group perturbation theory expressions for reactivity changes due to fuel burnout and uniform poison removal may then be equated and integrated under plausible simplifying restrictions to yield an expression for charge life in terms of calculable, or measurable quantities.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25444

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

This paper presents a brief study of fission product gamma-ray power as a function of time after shutdown for periodic reactor operation as compared to constant power operation. The basic decay formula of Way and Wigner is used.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25445

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

The conventional kinetics equations for reactors in which fuel is stationary are derived without approximation from the time-dependent transport equation. The utility of the precise form which results is discussed, first generally, then with reference to the detailed analysis of two typical experiments. It is shown that the analysis required for a precise interpretation of kinetics experiments can generally be made using the same techniques employed in the computation of criticality for stationary cases.

ISSN:0029-5639    

DOI:10.13182/NSE58-1

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

A generalization of the Serber-Wilson method has been used to derive an expression for the one neutron group self-shielding factor for an absorbing material alternating with a pure moderator and scatterer in a simple plane lattice. The formula has been found as accurate as a considerably more complicated double spherical harmonic calculation.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25447

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

A form for the point-source gamma-ray energy absorption buildup function valid for a material in the energy range where it is essentially a Compton scatterer is suggested as a modification of the asymptotic forms derived by U. Fano. Its parameters are evaluated by means of an energy equilibrium condition and a fit to experimental data. The results are compared with those obtained by other methods, and an application to the problem of uniformly and continuously distributed point sources is discussed.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25448

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor

摘要:

Radial temperature distributions within the cores of heterogeneous circulating-fuel reactors having elementary channel and circular pipe geometries are described mathematically; uniform and nonuniform radial volume-heat-source distributions are considered. Solutions for cores with uniform volume-heat source distributions are tabulated so that detailed radial temperature profiles can be determined within fuels which are being uniformly cooled at the core walls. A derivation is presented which describes the heat transfer within a reactor core when walls are being non-uniformly cooled along its length; volume heat sources also exist within the core walls and coolant.

ISSN:0029-5639    

DOI:10.13182/NSE58-A25449

出版商:Taylor&Francis    

年代:1958

数据来源: Taylor