Browsing by Author "Lee, EJ"

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    Development of a pilot plant for the removal of rhenium from molybdenum trioxide
    (Australian Atomic Energy Commission, 1985-12) Lee, EJ; Sorby, PJ; Barnes, RK; Boyd, RE
    Reagent grade molybdenum trioxide used as a target material for the preparation of Tc-99m pharmaceuticals contains trace amounts of rhenium. A simple charcoal adsorptions process has been developed to remove rhenium selectively from molybdenum before neutron irradiation. Details are given of the design and operation of a pilot plant in which 17 kg of molybdenum trioxide was produced having a rhenium content of less than 1 x 10 -6 mu g g -1. Although contamination of the Tc-99m by inactive rhenium and 188 Re was effectively eliminated 188 Re resulting from the irradiation of tungsten impurity in the molybdenum trioxide target was still present.
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    High temperature compatibility of 25/20 type austenitic stainless steel with carbon dioxide
    (Australian Atomic Energy Commission, 1962-09) Lee, EJ; Draycott, A
    The 25% Cr, 20% Ni type stainless steel has been proposed for use in the Australian High Temperature Gas Cooled Reactor in core structures, and in hot gas ducting. Thus a knowledge of the compatibility of this steel with high pressure carbon dioxide was required. Rates and mechanisms of corrosion were investigated for machined, vapour blasted, and etched pretreated samples of this steel, exposed to carbon dioxide up to 5,000 hours in the temperature range 650ºC to 800ºC at gas pressures from 3 p.s.i.g. to 280 p.s.i.g. Oxide film flaking was apparent at all temperatures investigated, but was only severe for pre—ground samples at 710ºC and above, and for pre—vapour blasted samples at 760ºC and above. However, severe intergranular penetration was observed in preetched samples on exposure to carbon dioxide at 650ºC and above. Pressure of the gas appeared to have no systematic effect on the corrosion rate, at least in the temperature range investigated. The maximum useful temperature for which the steel could be used would be limited by the amount of oxide flaking permissible. In reactor gas circuits where a small amount of scale flaking could be tolerated, the steel is satisfactory up to 750ºC.
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    Laboratory development of the grind-leach process for the H.T.G.C.R. fuel cycle, Part 4 - leaching and dissolution of beryllia-based fuels
    (Australian Atomic Energy Commission, 1967-07) Shying, ME; Lee, EJ; Farrell, MS
    This report covers the chemical development of an acid-leach head-end process for the separation of (U,Th)02 from a beryllia matrix. The work is related to a feasibility study of the H.G.T.C.R. fuel cycle. Although more than 99 per cent of the actinides can be recovered in a single batch nitric acid leach, more than 30 per cent of the beryllia is dissolved. When it was found that sulphuric acid selectively dissolved the beryllia, a two-step process using nitric and sulphuric acids in sequence was developed, with recycling of the actinide-rich heel to the next batch. Preliminary results from multi-batch experiments indicate that it might be possible to decrease the beryllia loss to the nitrate stream to 10 per cent and still recover 99 per cent of the actinides. Further development of the process would involve the use of proven reactor material irradiated to high burn-up. Suggestions for further research are given.