Browsing by Author "Charlton, BG"

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    Comparison of costs of conventional fluorination and improved fluorox processes for the production of uranium hexafluoride
    (Australian Atomic Energy Commission, 1975-05) Charlton, BG
    Capital and operating costs for direct fluorination and two schemes of improved Fluorox plants are compared for a uranium throughput of 3,000 Mg y-1. Scheme I involves the recycle of uranyl fluoride (UO2F2) through separate reduction and hydrofluorination steps, while in Scheme II the reduction and hydrofluorination of recycle UO2F2 is carried out in one step. There are savings in total capital requirement of approximately $982,000 for the Scheme I Fluorox plant and approximately $2,156,000 for the Scheme II Fluorox plant compared with a total capital requirement of approximately $14.6 x 106 for the conversion of yellow cake to uranium hexafluoride via direct fluorination. Annual expenditures (including capital charges) are reduced by $480,000 and $848,000 for the two Fluorox plants respectively, saving $0.16 kg-1 and $0.28 kg-1 respectively in the cost of conversion of yellow cake to uranium hexafluoride compared with $2.43 kg-1 reported for a direct fluorination plant.
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    Development of processes for pilot plant production of purified uranyl nitrate solutions
    (Australian Atomic Energy Commission, 1975-01) Alfredson, PG; Charlton, BG; Ryan, RK; Vilkaitis, VK
    Nuclear purity uranyl nitrate solutions were produced from Rum Jungle yellow cake by dissolution in nitric acid and purification by solvent extraction with 20 vol.% tributyl phosphate in kerosene using pump -mix mixer-settler contactors. The design of the equipment, experimental studies and operating experience are described. Dissolution of yellow cake and recycled uranium oxide materials was readily carried out in a 100 ℓ dissolver to give solutions containing 300 gU ℓ -1 and 0.5 to 4 П nitric acid. Filtration of silica from this solution prior to solvent extraction was not necessary in this work for yellow cake containing 0.25 per cent silica. A low acid flowsheet for uranium purification was developed in which the nitric acid consumption was reduced by 76 per cent and the throughput of the mixer-settler units was increased by 67 per cent compared with the initial design flowsheet. Nine extraction and seven scrubbing stages were used with a feed solution containing 300 gU ℓ -1 and 1.0 П nitric acid and with a portion of the product recycled as scrub solution. The loaded organic phase was stripped in 16 stages with 0.05 П nitric acid heated to 60º C to give a 120 gU ℓ -1 product. The uranium concentration in the raffinate was < 0.04 g ℓ-1, corresponding to ~ 0.01 per cent of the feed.
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    Preliminary design and cost considerations for a plant to produce nuclear purity uranium dioxide from Australian ore concentrates
    (Austtalian Atomic Energy Commission, 1971-03-01) Charlton, BG; Alfredson, PG
    Design considerations are outlined for plants for the production of nuclear purity uranium dioxide with capacities of 100, 200 and 500 tonnes U/year. The cost of the process equipment is not greatly affected by various process alternatives; equipment performance, which affects product quality, consistency of power properties and plant reliability, is important in determining the recommended process. This involves the following steps: batch dissolution, continuous solvent extraction in mixer-settlers, single-stage precipitation of ADU, thickening and spray drying of ADU, and calcination-reduction in continuous pulsed fluidised bed reactors. Estimates of the cost of recovery of free acid and combined nitrate from the raffinate and filtrate waste streams indicated that the value of the recovered acid would be greater that the processing cost only in the case of free acid recovery from solvent extraction raffinate in the 500 tonne/year plant. However if acid recovery is necessary for plant effluent control, the processing cost can be largely offset by the value of the recovered acid.
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    Preliminary design and cost considerations for a plant to produce nuclear purity uranium dioxide from Australian ore concentrates
    (Australian Atomic Energy Commission, 1971-03) Charlton, BG; Alfredson, PG
    Design considerations are outlined for plants for the production of nuclear purity uranium dioxide with capacities of 100, 200 and 500 tonnes U/year. The cost of the process equipment is not greatly affected by various process alternatives; equipment performance, which affects product quality, consistency of power properties and plant reliability, is important in determining the recommended process. This involves the following steps: batch dissolution, continuous solvent extraction in mixer-settlers, single-stage precipitation of ADU, thickening and spray drying of ADU, and calcination-reduction in continuous pulsed fluidised bed reactors. Estimates of the cost of recovery of free acid and combined nitrate from the raffinate and filtrate waste streams indicated that the value of the recovered acid would be greater that the processing cost only in the case of free acid recovery from solvent extraction raffinate in the 500 tonne/year plant. However if acid recovery is necessary for plant effluent control, the processing cost can be largely offset by the value of the recovered acid.
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    Production of uranium hexafluoride by the catalysed fluorox process: pilot plant and supporting bench-scale studies
    (Australian Atomic Energy Commission, 1982-04) Janov, J; Charlton, BG; Le Page, AH; Vilkaitis, VK
    The feasibility of producing UF 6 by the catalysed reaction of UF 4 with oxygen (the Fluorox process) was investigated in a 150 mm diameter fluidised bed reactor and in supporting bench-scale experiments. The rate of the Fluorox reaction in batch experiments was increased by an order of magnitude with 1 to 5 per cent catalyst (containing 3 to 4 per cent platinum on alumina). The maximum UF 6 production rate at 650 deg. C was 0.9 kg h -1. However the platinum catalyst was completely poisoned after production of only 1 and 20 kg UF 6 per kg of catalyst when using respectively French and British UF 4. Regeneration of the catalyst was demonstrated to be technically feasible by washing with water or ammonium oxalate solution or treating with hydrogen and hydrogen fluoride at 350-650 deg. C. However since the very fast rate of poisoning would necessitate higher catalyst concentrations and/or frequent regeneration the catalysed Fluorox process in unlikely to be economically competitive with the direct fluorination of UF sub 4.
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    Thermal denitration of uranyl nitrate in a fluidised bed reactor
    (Australian Atomic Energy Commission, 1974-07) Fane, AG; Charlton, BG; Alfredson, PG
    Commissioning and operating experience are described for the thermal denitration of uranyl nitrate in a 0.1 m diameter fluidised bed reactor. The effects of operating temperature, uranyl nitrate concentration and feed rate, nozzle air to liquid flow ratio, and the addition of sulphate to the feed, on the characteristics of the product and equipment performance were examined. Particle growth was a predominant feature which was strongly influenced by operating temperature. Changes in the main process variables exerted a minor influence on other properties of the product. The addition of sulphate to the uranyl nitrate feed solution produced an increase in surface area, and a decrease in pour and tap density. The wall-to-bed heat transfer coefficient was in the range 190 to 265W nf 2K-1, and shown to be an inverse function of the average particle size.