Thermal Neutron Flux Spectrum in a Medium with a Temperature Discontinuity

Kottwitz, D.A.

doi:10.13182/nse60-a25728

Cited by 28 publications

(6 citation statements)

References 1 publication

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“…An important advantage of our numerical approach is that we need make no major simplifying assumptions to facilitate the analysis. For example the early classic analysis of Kottwitz (1960) for this problem, using diffusion theory, assumes no absorption or neutron sources in the moderator. These assumptions are also made by the later transport theory analyses of Williams (1965Williams ( , 1968, Jauho and Virjo (1968) and Gritton and Leonard (1969).…”

Section: Introductionmentioning

confidence: 99%

Thermal neutron transport near a moderator discontinuity using the method of weighted residuals: III. Temperature discontinuities in graphite and light water

Beynon¹,

Moon²

1973

J. Phys. D: Appl. Phys.

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A detailed analysis is made of the spatial variation of the effective thermal neutron temperature near temperature discontinuities in large volumes of graphite and light water. For graphite comparisons are made with recent measurements by Day. It is seen that it is important that proper consideration be made for the gradient of the epithermal flux. For water a number of predictions are made for both poisoned and unpoisoned systems and some doubt is cast on the feasibility of such measurements for determining the accuracy of different scattering kernels for light water. It is demonstrated, for both graphite and light water, that additional information can be obtained by extracting neutron beams at angles other than perpendicular to the axis of the system.

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Section: Introductionmentioning

confidence: 99%

Thermal neutron transport near a moderator discontinuity using the method of weighted residuals: III. Temperature discontinuities in graphite and light water

Beynon¹,

Moon²

1973

J. Phys. D: Appl. Phys.

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“…In a previous publication (Williams 1965), the author has described a method for computing the neutron flux in a medium with a non-uniform physical temperature. This technique employed the heavy gas model of scattering and the full transport equation; in this way errors arising from diffusion theory in the Kottwitz problem were assessed (Kottwitz 1960) Jauho and Virjo have extended the author's original equation to arbitrary geometry, and in particular to spherical systems, thereby calculating the effect of the radius of curvature of a temperature discontinuity (Jauho and Virjo 1968). The complete flux distribution has also recently been derived for the Kottwitz problem by the application of Case's method of singular eigenfunctions (Gritton and Leonard 1967).…”

Section: Introductionmentioning

confidence: 99%

A new synthetic scattering kernel with applications in neutron transport theory

M M R Williams

1968

J. Phys. D: Appl. Phys.

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A new synthetic kernel, based on the secondary model of neutron scattering, is derived. The new model reproduces infinite-medium spectra in 1/v-poisoned media with considerable accuracy and behaves in many ways like a real, chemically bound moderator. The eigenfunctions of the scattering operator defined by the new kernel are found to be Laguerre polynomials but, unlike the heavy gas model which also has Laguerre polynomial eigenfunctions, the eigenvalues have a limit point behaviour. This fact enables the space eigenvalues of the transport equation to assume a particularly useful form and overcomes the anomalous behaviour observed when the heavy gas model is employed. The new kernel is more accurate than the heavy gas model, being valid for all values of moderator mass. It is also just as convenient from an analytical point of view, as illustrated by an example based on neutron diffusion in a temperature gradient.

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“…Kottwitz (11) has applied two simple schemes to the problem Figure 9» Deviation of flux spectrum from Maxv;ellian due to absorption only, due to non-uniform temperature only and due to both absorption and non-uniform temperature in an non-absorption medium. Of these, the neutron tem perature approximation which assumes that the thermal energy neutrons have a Haxwellian spectrum at every point in space has been shown to be less satisfactory than the other method due to Selengut (12), Recently, Pearce and Kennedy (21) have worked out the same problem as considered by Kottwitz by applying multigroup technique.…”

Section: Discussionmentioning

confidence: 99%

Temperature dependent neutron thermalization

Charyulu

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Thermal Neutron Flux Spectrum in a Medium with a Temperature Discontinuity

Cited by 28 publications

References 1 publication

Thermal neutron transport near a moderator discontinuity using the method of weighted residuals: III. Temperature discontinuities in graphite and light water

Thermal neutron transport near a moderator discontinuity using the method of weighted residuals: III. Temperature discontinuities in graphite and light water

A new synthetic scattering kernel with applications in neutron transport theory

Temperature dependent neutron thermalization

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