摘要:

AbstractA technique is presented for conducting neutron-wave experiments in thermal-neutron systems using either a sinusoidally modulated or a pulsed source of thermal neutrons. A neutron source suitable for this experiment is described, data-accumulation criteria are presented, and the electrical systems used for collection are discussed. A specific experiment with graphite is reported and the discussion of data analysis is carried through the experimental determination of this system's dispersion law. It is found that, in general, a pulsed source of thermal neutrons is more suitable for neutron-wave experimentation than a sinusoidally modulated source. Confirmation is given to the theoretical prediction that diffusion and thermalization parameters can be measured by this technique over a relatively wide range of frequency without significant higher space- and energy-mode contamination. The values we obtained for the diffusion and thermalization parameters for graphite of density 1.60 g/cm3wereα0±91.±1 sec−1,D0= (2.16±0.01)×105(cm2sec−1),C0= (39.±2)×105(cm4sec−1), andF0= (12.±2)×107(cm6sec−1).

ISSN:0029-5639    

DOI:10.13182/NSE67-A28955

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

AbstractAn approximate theory for the slowing down of neutrons in a nonmultiplying medium with plane symmetry is described. The theory is based on an approximate form of the transfer function for elastic scattering under the hypothesis that the mass number of the moderator is larger than one. In theA−Napproximation the slowing down equation is reduced to a finite system of differential equations with respect to the lethargy variable. A detailed study has been made of the results obtained in theA−Napproximation withN= 0 andN= 1. Special attention has been paid to a comparison of theA−1approximation with age theory and asymptotic theory.

ISSN:0029-5639    

DOI:10.13182/NSE67-A28956

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

AbstractThe method of flux synthesis is extended in a systematic way to allow the possibility of using different sets of trial functions in different axial zones. The necessary equations are derived in some detail and numerical examples are presented. The results of these examples are very satisfactory and suggest, therefore, that the synthesis procedure can be made much more useful and powerful by extending it in this way. In a more general context they suggest that the basic notation of deriving discontinuous-type approximation methods from an appropriate variational principle is a valid and very effective idea.

ISSN:0029-5639    

DOI:10.13182/NSE67-A28957

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

AbstractA general method for replacing a rigorous equation by a set of approximate equations with a reduced number of independent variables is presented. The modal-expansion method includes, as special cases, many of the techniques employed in reactor-physics calculations: harmonic analysis, polynomial expansions, semi-direct variational methods, weighted-residual methods, region balance, etc. The mathematical significance of the procedure is discussed in terms of the representation of a linear operator equation on a linear vector space. The concept of a“best”set of approximate equations is examined with respect to certain error criteria.

ISSN:0029-5639    

DOI:10.13182/NSE67-A28958

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

摘要:

AbstractThree new models have been developed for fast-reactor physics calculations. These were obtained from the energy-dependentP1equations by a modal expansion of the neutron flux. For certain classes of problems, these models provide attractive alternatives and supplements to conventional multigroup finite-difference models, in that considerable reductions in complexity and computational effort are realized. Integral experimental data can be used directly in one of the models, and physical insight can be incorporated into all the models via the choice of expansion modes. Each of the models was applied to calculate the integral properties of fast-reactor critical assemblies.

ISSN:0029-5639    

DOI:10.13182/NSE67-A28959

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE67-A28960

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE67-A28961

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE67-A28962

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE67-A28963

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor

ISSN:0029-5639    

DOI:10.13182/NSE67-A28964

出版商:Taylor&Francis    

年代:1967

数据来源: Taylor