Browsing by Author "Bardsley, J"

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    Fabrication of U233/aluminium fuel plates for a sub-critical assembly - a second report
    (Australian Atomic Energy Commission, 1967-08) Bardsley, J; Ridal, A
    Uranium-233 (as 938..66 g uranium dioxide) was fabricated into 176 full-size, 20 'half-size' and 2 'quarter-size' aluminium clad fuel plated. Each full-size plate contained 5 compact and 'half-size' and 'quarter-size' plates contained 2 compacts and 1 compact respectively; a compact consisted of a cold-pressed dispersion of about 1.5 g of uranium dioxide in aluminium. The technique involved mixing uranium dioxide and aluminium powders, pressing the compacts in a steel die, end-loading them into a prefabricated aluminium can and end-welding the can; following this the can underwent radiographic inspection for uniformity, decontamination, leak detection and acceptance tests, and final decontamination. Maximum permissible radiation doses to hands and bodies of the operators were not exceeded.
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    The hot pressing of beryllium oxide with additives.
    (Australian Atomic Energy Commission, 1968-02) Bardsley, J; Wulf, G
    The effect of variations in temperature, pressure and pressure cycle on the density vs grain size relationship was determined for hot pressed, sulphate-derived UOX beryllium oxide; the effects of selected additives on the final grain size using constant hot pressing conditions were also determined. A single-ended pressing technique, incorporating an incremental build-up in the pressing pressure, was developed to produce hot pressed specimens of near theoretical density with a uniform grain size of 25u. Smaller grain sizes were not obtained by this technique owing to the onset of discontinuous grain growth at a bulk density of 97 per cent theoretical. However, by introducing a 'dwell' or 'equilibration' time at temperature before the application of the load, a theoretically dense specimen (3.010 g/cm3) was produced with a uniform 8u grain size. Carbon was the only additive which consistently refined the grain size at all levels of addition. A hot pressed specimen of 99 per cent theoretical density and 2u grain size was obtained using a standard condition of 1500°C, 250 kg/cm2 for 25 minutes, 5 volume per cent of colloidal graphite additive.
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    An improved method for extruding and sintering beryllium oxide.
    (Australian Atomic Energy Commission, 1967-08) Bardsley, J; Ridal, A
    A technique for the extrusion and sintering of beryllium oxide to produce high density, fine-grained, high strength material were modified and improved. This resulted in beryllium oxide (250 p.p.m. Fe) which after extrusion and sintering for 5 hours at 1400oC in nitrogen, had an average grain size 6 pts, a mean modulus of rupture equal to 34.840 p.c.i. when tested in 4-point bentiac and a density range of 2.86 to 2.90 g cm-3. Further modifications reduced the variations in grain size and density of the sintered specimens and increased the mean modulus of rupture. For example, double extruded material, when sintered for 6 hours at 1400oC in nitrogen had an average grain size of 8pm, a density of 2.92 g cm-3 and a mean modulus of rupture of 45,300 p.s.i.