The production of sinterable uranium dioxide from ammonium diuranate, Part 3 - continuous production in a pulsed fluidised bed reactor
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Date
1975-02
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Publisher
Australian Atomic Energy Commission
Abstract
The development of a 0.13 m diameter pulsed fluidised bed reactor for the continuous production of sinterable uranium dioxide from ammonium diuranate is described. Calcination-reduction at 670 to 680 ºC produced powders with surface areas of 4 to 6 m2 g-1 giving pellet densities in excess of 10.6 g cm-3.
Sinterability was relatively insensitive to changes in operating conditions, provided the availability of hydrogen was adequate, for gas flow rates in the range 0.95 to 1.4 ℓ s-1, pulse frequencies of 0.5 and 0.75 Hz and mean residence times of the solids from 0.6 to 1.4 hours. Sinterability was shown to be improved either by use of higher input concentrations, or by use of a secondary flow of hydrogen (about 5 per cent of input) fed into the powder collection system and flowing countercurrent to the U02 product. The maximum throughput of 17 kg U02 h-1 (0.6 hours mean residence time) required only 120 per cent of the stoichiometric requirement at an input concentration of 50 vol.% with secondary hydrogen flow. Results are given for studies of the kinetics of reduction of calcined ammonium diuranate in hydrogen and the residence time distribution of solids in a pulsed fluidised bed. Estimates based on these data suggested that the overall conversion of ammonium diuranate to uranium dioxide in the continuously operated pulsed fluidised bed reactor was in excess of 99 per cent. Continuous stabilisation of the U02 product was demonstrated at 12 kg h-1 of U02, in a 0.15 m diameter glass stabiliser, using 10 vol.% air in nitrogen and a temperature of about 50ºC.
Description
Keywords
Uranium dioxide, Fluidized bed reactors, Calcination, Chemical reaction kinetics, Sintering
Citation
Fane, A. G., & Le Page, A. H. (1975). The production of sinterable uranium dioxide from ammonium diuranate : part 3, continuous production in a pulsed fluidised bed reactor (AAEC/E347). Lucas Heights, NSW: Australian Atomic Energy Commission Research Establishment.