Browsing by Author "Duerden, P"

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    Alligator Rivers analogue project an OECD/NEA international project
    (The Institution of Engineers Australia, 1994-05-01) Duerden, P; Pescatore, C; Airey, PL
    The Koongarra uranium deposit in the Alligator Rivers Region of the Northern Territory of Australia was studied as a natural analogue of the far field behaviour of high level waste repositories following groundwater ingress. A number of mathematical modelling approaches were developed for processes as diverse as groundwater transport, host rock weathering, radionuclide sorption, evolution of the uranium dispersion fan and the distribution of uranium series nuclides between mineral assemblages in weathered host rock. Some of these models are relevant to performance assessment at the level of individual processes and subsystem performance. Through the project, new insights into the application of the natural analogue approach to the assessment of potential waste repository sites were obtained.
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    Application of proton induced x-ray emission to the element analysis of thick obsidian samples
    (Australian Atomic Energy Commission, 1979-11) Duerden, P; Cohen, DD; Clayton, E
    The proton induced x-ray emission (PIXE) technique has been applied to the analysis of element concentrations in obsidian source samples. No target preparation other than washing and the selection of a flat surface was undertaken. Thick target yields have been calculated and element concentrations derived from the detected X-ray spectra; concentrations are given for K, Ca, Ti, V, Mn, Fe, Ga, As, Rb, Sr, Y, Zr, Nb, Ta, and Pb. A pinhole filter is described which enables a single measurement of about 5 minutes duration to give element concentration data over an x-ray energy range 3-20 keV.
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    Buckling and integral spectrum measurements in Pu239/BeO sub-critical assemblies
    (Australian Atomic Energy Commission, 1967-06) Duerden, P
    The materials buckling of four BeO moderated Pu239/aluminium - alloy fuelled systems having BeO/Pu239 atomic ratios of 1707, 2499, 3749 and 4999 have been measured by the exponential method. Relative fission rates of U233, U235 and Pu239 were also measured in the equilibrium spectrum region of the same assemblies. Because of the heterogeneous nature of the assemblies, fine structure corrections were applied. Some calculations using the CRAM diffusion code, and some using the GYMEA code are included.
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    Buckling and integral spectrum measurements in U233/BeO sub-critical assemblies
    (Australian Atomic Energy Commission, 1965-11) Brittliff, E; Duerden, P
    The materials buckling of three BeO moderated U233 oxide fuelled systems having BeO/U233 ratios of 6496, 4331, and 3248 have been measured by the exponential method. Relative fission rates of U233, U235, and Pu239 were also measured in the equilibrium spectrum region of the same assemblies. Because of the heterogeneous nature of the assembly, fine structure corrections have been applied. Some calculations using the CRAM Diffusion Code have been included.
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    Buckling and integral spectrum measurements in U235 fuelled sub-critical assemblies moderated by BeO/fertile material mixtures
    (Australian Atomic Energy Commission, 1965-12) McCulloch, DB; Duerden, P; Brittliff, E
    Exponential experiments have been carried out to give the materials buckling of a number of near—homogeneous U235/aluminium alloy fuelled systems having fertile oxides intimately mixed with the BeO moderator. Relative fission rates of U235, U233, and Pu239 were also measured in the equilibrium spectrum region of each assembly. Five assemblies having 5 w/o natural uranium oxide in BeO were investigated for a range of BeO/U235 atomic ratios from 1500: 1 to 5700: 1. A similar range covering four assemblies was examined for 5 w/o thorium oxide in BeO. A comparison of the experimental results with diffusion theory calculations is included.
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    Buckling and integral spectrum measurements in U235/BeO sub-critical assemblies
    (Australian Atomic Energy Commission, 1964-07) Duerden, P; McCulloch, DB; Brittliff, E
    The materials buckling of four BeO moderated U235/aluminium alloy fuelled systems having BeO/U235 ratios of 1465, 2930, 5860, and 8790 have been measured by the exponential method. Relative fission rates of U235, U233, and Pu239 were also measured in the equilibrium spectrum region of the same assemblies. The experiments are described in detail, and the results compared with the predictions of a simple spectrum model (Westcott) pending analysis using more complex calculatlonal models.
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    A comparison of PIXE and neutron activation techniques for thorium and uranium ore analysis
    (Australian Atomic Energy Commission, 1980-04) Cohen, DD; Duerden, P; Wall, T; Clayton, E
    Proton induced x-ray emission (PIXE) and neutron activation analysis (NAA) techniques are used to estimate the concentrations of trace quantities of thorium and uranium in powdered rock or ore samples. The accuracy of the two methods is compared in both a carbon matrix and a variety or ore matrices over the concentration range 1 to 10 000 µg g-1. Under the test conditions the PIXE and NAA concentration estimates for any individual sample in this range are found to be the same within a 3o standard error of 9 per cent.
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    Dating, mass spectrometry and nuclear science: a proposed new facility at Lucas Heights.
    (Australian Atomic Energy Commission, 1984-01) Bird, JR; Airey, PL; Boldeman, JW; Cohen, DD; Duerden, P
    It is proposed that the AAEC install a high-technology, multi-user facility based on an 8 MV tandem accelerator to provide new capabilities in the following fields: (a) Radioisotope dating and ultra-sensitive trace element determination in isotope hydrology, salinity, sedimentology, erosion, actinide transport and materials studies. (b) Physics studies for the development of methods of applying nuclear materials safeguards, the provision of neutron dosimetry standards, measurements of precision data for radiation interactions, and the development of new methods for radioisotope dating. (c) Development of nuclear and ion beam techniques with applications in occupational health, biomedicine, materials modification, industrial problems and other fields. (d) Special requirements for accelerator-based radiocarbon dating of geological and archaeological samples not provided by other laboratories, coordinated by the Australian National University. These primary objectives include collaborative projects with the Bureau of Mineral Resources, Geology and Geophysics (BMR), the NSW Water Resources Commission (NSWWRC) and, under the auspices of the Australian Institute of Nuclear Science Engineering (AINSE), with Australian universities and other advanced educational institutions. Existing inter-regional programs in hydrology and neutron physics would also be served by the proposed facility making possible an expansion in the scope of joint projects with other countries in the SE Asian region.
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    The determination of trace quantities of thorium and uranium in thick ore samples by proton-induced x-ray emission.
    (Australian Atomic Energy Commission., 1979-07) Cohen, DD; Duerden, P; Clayton, E
    Proton-induced x-ray emission (PIXE) techniques have been used to estimate the concentrations of trace quantities or thorium and uranium in powdered rock and ore samples. Standards of known concentrations were prepared in a carbon matrix and the yields from these used to determine simultaneously the concentrations of thorium and uranium in the ore samples. The experimental detection limit of the technique was found to be 3 to 4 µg g-1 for a 100 µC irradiation. The appropriate matrix corrections for a carbon and ore matrix have been calculated for thick targets and taken into consideration.
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    Measurement of a modified relative conversion ratio in multi-rod clusters
    (Australian Atomic Energy Commission., 1975-09) Duerden, P
    An Indo-Australian experiment is described in which relative conversion ratios for a range of U02 rod cluster fuel elements in a heavy water moderated reactor were measured using a high resolution Ge(Li) detector to measure directly the neptunium activity following neutron capture in 238U. The results are compared with calculations made with the UKAEA lattice code WIMS
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    Proton induced x-ray emission (PIXE) analysis at Lucas Heights
    (Australian Atomic Energy Commission, 1979-02) Cohen, DD; Duerden, P
    State of the proton induced x-ray emission (PIXE) work at Lucas Heights is reported together with a full description of the experimental arrangement and its use for analysis of trace elements (Z > 14). The fundamentals of PIXE are examined in detail with a view to understanding not only the background continuum but also the x-ray production mechanisms. Quantitative predictions for the number of x-rays detected after proton bombardment of the target have been made and these compare well with experiments.