Browsing by Author "McGregor, BJ"

Now showing 1 - 7 of 7
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    Comparison of calculations made with three time-dependent neutron codes TDA, MORSE and POW
    (Australian Atomic Energy Commission, 1974-12) McGregor, BJ; Harrington, BV
    Three computer codes were compared to determine their usefulness in analysing a pulsed neutron experiment. The codes were a Monte Carlo code (MORSE) a diffusion kinetics code (POW) and a time dependent SN code (TDA). A series of test problems were devised to progressively model the experiment. All problems assumed a spherical system with an isotropic source. The first problem had its source in the first energy group for the first nanosecond. The second problem had its source distributed in time but not distributed in energy. The third problem had a source distributed in energy and time. POW and MORSE were shown to be in good agreement, with significant differences occurring only at times when the system did not correspond with the approximations made in POW. The AAEC version of the TDA code did not handle a time-dependent source. There was also a tendency for the results beyond 50 ns to be higher than those for the other two codes for the problems having a source constant over one time interval.
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    Comparison of calculations of a reflected reactor with diffusion, sn and monte carlo codes
    (Australian Atomic Energy Commission, 1975-01) McGregor, BJ
    A diffusion theory code, POW, was compared with a Monte Carlo transport theory code, KENO, for the calculation of a small C/235U cylindrical core with a graphite reflector. The calculated multiplication factors were in good agreement but differences were noted in region-averaged group fluxes. A one-dimensional spherical geometry was devised to approximate cylindrical geometry. Differences similar to those already observed were noted when the region-averaged fluxes from a diffusion theory (POW) calculation were compared with an SN transport theory (ANAUSN) calculation for the spherical model. Calculations made with SN and Monte Carlo transport codes were in good agreement. It was concluded that observed flux differences were attributable to the POW code, and were not inconsistent with inherent diffusion theory approximations.
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    Conversion of the neutron code TDC to FORTRAN IV
    (Australian Atomic Energy Commission, 1967-02) McGregor, BJ
    The conversion of the code TDC from CDC 1604 FORTRAN to FORTRAN IV is discussed with some notes on additional options provided. A series of test problems was devised and run and some points on code usage are reported. The preparation of input data is not described. This is given in the TDC User's Guide by Rodgers and Check (1965).
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    Effect of the bore hole on nuclear logging measurements
    (Australian Atmoic Energy Commission, 1983-12) McGregor, BJ; Eisler, P
    An analytical study with sand representing an ore was undertaken to find whether the ratio of the characteristic gamma-ray flux to thermal neutron flux in a bore hole can be reliably used as a measure of the characteristic element particularly if the water content of the ore is unknown. Both Monte Carlo and two-dimensional transport theory methods were used and found to be in good agreement but the use of two-dimensional transport theory is preferred for speed. A homogeneous analysis which ignores the effect of the bore hole and probe is compared to the detailed representation. It is shown that when the bore and probe are represented in the analysis there is a significant variation with water content of the ratio of the characteristic gamma-ray flux to the thermal neutron flux. This variation is not accurately predicted by the homogeneous model which is therefore inadequate.
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    IBM 360 version of the neutron diffusion code CRAM
    (Australian Atomic Energy Commission, 1968-01) McGregor, BJ; Richards, AG; Wood, RGJ
    The A.A.E.C. 360 CRAM program, written in FORTRAN IV and ASSEMBLER, is designed to run under the 360 operating system on a 256K model 50. The program can readily be changed to take advantage of additional storage that may be available on other 360 configurations. The code includes standard output routines as well as providing the user with the facility of including his own FORTRAN coded output routines. The code package includes sets of test problems for both one and two dimensional geometries.
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    Monte Carlo calculations of time-dependent neptunium-237 and uranium-235 fission rates in a pulsed thorium assembly
    (Australian Atomic Energy Commission, 1977-11) McGregor, BJ
    A series of integral pulsed neutron experiments in a thorium assembly have been performed. Monte Carlo calculations are presented of the 237Np and 235U fission rates as a function of space and time. Calculations assuming spherical symmetry are compared with those which represent the geometry of the experiment nearly exactly, and both are compared with the experimental results. It is shown that the calculations give similar results for the simplified and actual geometries. It is concluded that the observed differences between calculation and experiment are not due to errors in the calculations introduced by the use of simplifying geometric assumptions.
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    Tritium breeding experiments in a fusion blanket assembly using a low-intensity neutron generator
    (Australian Atomic Energy Commission, 1987-01) Dalton, AW; Woodley, HJ; McGregor, BJ
    Experiments have been carried out to determine the accuracy with which tritium production rates (TPRs) can be measured in a fusion blanket assembly of non-spherical geometry by a non-central low intensity D-T neutron source. The tritium production was determined for samples of lithium carbonate containing high enrichments of 6 Li(96%) and 7 Li(99.9%). The measured data were used to check the accuracy with which the TPRs could be numerically predicted using current nuclear data and calculational methods. The numerical predictions from tritium production from the 7 Li samples agreed within the experimental errors of the measurements but 6 Li measurements which differ by more than 20 per cent from the predicted values which were observed in the lower half of the assembly.