Browsing by Author "Keane, A"

Now showing 1 - 9 of 9
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    A derivation of the effective resonance integral in heterogeneous systems
    (Australian Atomic Energy Commission, 1959-08) Keane, A; McKay, MH; Cox, CD
    This paper is concerned with the evaluation of the effective resonance integral for a close-packed lattice of fuel elements in beryllium oxide moderator. For this evaluation the usual theory of resonance absorption is extended to allow for flux depression in the moderator. Further, the fuel elements under consideration consist of clusters of seven rods, so that it is necessary to determine the effective surface area for such a cluster. When the fuel elements are composed of U235, Th232 and Be atoms in the ratio of approximately 1:35:1200 and the BeO moderator occupies almost three and half times the volume of the fuel rods, the effective resonance integral is found to be almost about 60% of the value for a homogeneous system of the same composition.
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    The doppler coefficient for reactors containing thorium
    (Australian Atomic Energy Commission, 1960-06) Keane, A; McKay, MH; Clancy, BE
    The Doppler increase in the effective resonance integral has been calculated for a model absorber which approximates the resonance structure of Th232. The results indicate that for rods of pure thorium the increase depends approximately on the square root of the temperature and very good agreement is obtained with experimental values of: 1/1 - dI/dT. The calculations also show that the addition of scattering material to the fuel rods will lessen the temperature dependence of the increase in the effective resonance integral.
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    Equivalence relations for heterogeneous reactor systems
    (Australian Atomic Energy Commission, 1966-12) Keane, A; McKay, MH
    A derivation is given of an equivalence relation between heterogeneous and homogeneous systems which allows for close—packing without the need for a Dancoff correction and which includes fuels dispersed in granular form. An alternative derivation of the equivalence relation is also presented giving insight into the physical significance of the rational approximation.
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    Equivalence relations for resonance absorption in small particles.
    (Australian Atomic Energy Commission, 1964-05) Keane, A
    The effective resonance integral for fertile material agglomerated into small particles can be evaluated to a good approximation by using a reduced scattering cross section per fertile nucleus. The proportion of the moderator scattering per nucleus obtained from two extreme assumptions has been checked against the exact solution for spherical particles.
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    High energy neutron spectra in infinite homogeneous reactor systems moderated by beryllium or beryllia.
    (Australian Atomic Energy Commission, 1962-07) Keane, A; Mills, RG
    A programme is described for determining the neutron enhancement due to the (n,2n) reaction in reactor systems moderated by beryllium. For moderation by pure beryllium the enhancement has been found to be 9-7 per cent.
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    Integrals involving doppler broadened contour functions.
    (Australian Atomic Energy Commission, 1964-03) Clancy, BE; Keane, A
    A variety of integrals arising in the study of resonance absorption have been evaluated.
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    MULGA - a complex of codes for the determination of multigroup averaged neutron cross section data
    (Australian Atomic Energy Commission, 1963-12) Clancy, BE; Doherty, G; Keane, A; Kletzmayr, EK; Pollard, JP
    A complex of computer programmes called MULGA is described which will produce multigroup cross sections in a format suitable for input into a selection of reactor codes. Always bearing in mind that the spatial variation of flux will frustrate any determination of "exact" cross sections the maximum accuracy has been striven for within the limitations of urgency and feasibility. The programmes; together with an associated microscopic data library tape, and a specialised monitor system, have been coded for an IBM 1620 computer with 4 magnetic tapes. The basic programmes MULGA 1 and MULGA 2 have already been adapted for an ISM 7090 and the whole series will be modified for the new site computer in 1964.
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    A study of the effective resonance integral and doppler coefficients of U238, Th232, and Pu240 using the code complex LUBRA
    (Australian Atomic Energy Commission., 1966-12) Keane, A; Kletzmayr, EK
    The effective resonance integral and Doppler coefficient of U238, Th232, and Pu240 have been studied in detail using the LUBRA complex of codes. Some earlier results were used for comparison to verify the validity of the LUBRA results discrepancies have been explained and confidence can be placed in the results given by the LUBRA codes.
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    The synthetic kernels of neutron slowing-down theory and a related expansion
    (Australian Atomic Energy Commission, 1966-06) Wilkins, CA; Keane, A
    Various approximate solutions of the integral equation for neutron moderation are obtained by truncating an asymptotic expansion for the collision density, a process which is shown to be equivalent to replacing the scattering kernel by an alternative synthetic kernel which permits "exact" solution of the integral equation. Truncation after one or two terms, and approximation of a constant in one case, yield the classical kernels. It is shown that the appropriate kernel to be used depends on the particular quantity under investigation. In particular, an illustration is given showing why the Wigner kernel is superior to that of GoertzeLand Greuling for calculating resonance absorption. Difficulties may arise when using the entire non—truncated series. It is shown that, for the sources of practical interest in reactor theory, these difficulties may be removed by splitting the source into two "components", one rapidly decaying and the other not. When the source is not known sufficiently accurately for this splitting to be done, the series must, in general, be truncated to avoid divergence. The method of obtaining a kernel by truncation is consistent with the matching of moments method.