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|Title: ||Production of sinterable uranium dioxide from ammonium diuranate, Part 2 - batch production in a pulsed fluidised bed reactor.|
|Authors: ||Fane, AG|
|Issue Date: ||Jul-1974|
|Publisher: ||Australian Nuclear Science and Technology Organisation|
|Abstract: ||The development of a 0.13 m diameter pulsed fluidised bed reactor for the production of sinterable uranium dioxide from ammonium diuranate is described. Both consecutive calcination and reduction (simple-batch operation) and simultaneous calcination and reduction (batch-continuous operation) were investigated. Sinterable uranium dioxide, giving pellet densities in excess of 10.6 g cm-3 after sintering at 1,600ºC in hydrogen for four hours, was produced by both modes of operation. The surface area of the uranium dioxide powder decreased with an increase in temperature of reduction; operating temperatures were typically 620ºC to 630ºC for simple-batch operation, and 670ºC to 700ºC for batch-continuous operation, to produce powders in the range of interest (4 to 6 m2g-1). Product characteristics were relatively insensitive to changes in the other operating variables. Satisfactory powders were produced by simple-batch operation with a hydrogen concentration of 25 volume per cent, gas flow rates from 0.95 to 1.9 ℓ s-1, pulse frequencies of 0.5 to 0.75 Hz, pulse chamber volumes of 2.8 and 11.3 ℓ, and either hot or cold charging of ammonium diuranate. The maximum bed of ammonium diuranate handled satisfactorily with simple-batch operation was 7 kg, and this corresponded to a maximum throughput of 5 to 6 kg h-1 uranium dioxide. For batch-continuous operation, satisfactory powders were produced with hydrogen concentrations from 15 to 75 volume per cent, gas flow rates from 0.95 to 1.4 ℓ s-l, pulse frequencies of 0.5 and 0.75 Hz, a pulse chamber volume of 2.8 ℓ, rates of feeding ammonium diuranate from 7 to 20 kg h-1, and bed depth to diameter ratios of approximately 3 to 7. An overall throughput of 12 kg h-1 of uranium dioxide was demonstrated using the batch-continuous mode of operation. Hydrogen consumption for both modes of operation was in the range 70 to 85 per cent of input.
Stabilisation was readily carried out as a simple-batch operation in a pulsed fluidised bed stabiliser, using 10 volume per cent air in nitrogen and a temperature of about 50ºC. The solids handling systems, which were developed and included penumatic, vibratory and screw conveying, are also described.|
|Appears in Collections:||Scientific and Technical Reports|
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