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CHEMICAL REACTIVITY OF URANIUM TRIOXIDE. PART 2. UO$sub 3$ HYDRATES

Journal Article · · Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II
DOI:https://doi.org/10.1039/tf9635900485· OSTI ID:4743285
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The preparation and decomposition of the hydrates of uranium trioxide are considered. The reactivity of UO/sub 3/ prepared by decomposition of these hydrates towards reduction to UO/sub 2/ and further conversion to UF/sub 4/ is studied as a function of the hydration-dehydration parameters. The hydration at 20 to 100 deg C of fluidized-bed'' UO/sub 3/ proceeds at different rates in liquid water and in water vapor, and different hydrates may be formed at the same temperature in metastable states. Three different monohydrates were identified and evidence is presented for the existence of two dihydrates. Hydration leads to a substantial volume expansion which is retained on subsequent dehydration, leaving UO/sub 3/ in an expanded porous form. Initially, the product contains amorphous UO/sub 3/ which recrystallizes exothermically to gamma UO/sub 3/ at approximates 500 deg C. Reduction of UO/sub 3/ prepared from the hydrates proceeds uniformly throughout the particle and is associated with a volume contraction. The reactivity of the product UO/sub 2/ towards hydrofluorination depends upon (i) the hydrate phase used, (ii) the conditions of the hydration process, (iii) the temperature of dehydration and reduction to UO/sub 2/. This dependence is analyzed in detail and a model is proposed for the sub-particle structure of the UO/sub 2/ which adequately accounts for its reactivity pattern. (auth)
Research Organization:
Atomic Energy Research Establishment, Harwell, Berks, Eng.
NSA Number:
NSA-17-018167
OSTI ID:
4743285
Journal Information:
Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II, Journal Name: Transactions of the Faraday Society (England) Superseded by J. Chem. Soc., Faraday Trans., I and II Vol. Vol: 59; ISSN TFSOA
Country of Publication:
Country unknown/Code not available
Language:
English

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Related Subjects

CHEMISTRY