The uranium-oxygen system: U3O8-UO3

Hoekstra, H.R.; Siegel, S. M.

doi:10.1016/0022-1902(61)80383-7

Cited by 175 publications

(88 citation statements)

References 20 publications

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“…At 600°C, a strong band appeared at 800 cm −1 due to the asymmetric stretching frequency of the uranyl group of U 3 O 8 . These TGA/DTA and IR spectroscopy results are consistent with the results of previous research reported in the literature (Cordfunke and Aling, 1963;Deane, 1961;Hoekstra and Siegel, 1961;Sato, 1976;Singh et al, 2004;Varga et al, 2011). All of the results of the studies of the other precipitates obtained under different conditions were similar to those previously described, although they are not presented in this paper.…”

Section: Properties Of Uranium Peroxidesupporting

confidence: 93%

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

et al. 2013

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a b s t r a c t a r t i c l e i n f oThe processes of uranium stripping from 30% tri-n-butyl phosphate (TBP) in "odorless" kerosene by H 2 O 2 solutions both with and without NH 4 OH added were investigated in the temperature range of 20-50°C and with a volumetric ratio of 1 between the organic and aqueous phases. The uranium was selectively precipitated in the form of uranium peroxide during stripping from the organic phase by hydrogen peroxide. The stripping of uranium increased with increasing H 2 O 2 content, increasing temperature and increasing concentration of NH 3 in the range of 0-15 g/L. The use of a heated solution (40°C) that contained 4 mol H 2 O 2 /mol U and NH 3 12 g/L resulted in 99.7% of the uranium being stripped from TBP in the form of uranium peroxide. The uranium peroxide obtained by stripping is a highly pure product that exists in two different hydrated forms: UO 4 •4H 2 O (92 mass %) and UO 4 •2H 2 O. The mean particle diameter was 20.75 μm. The effect of hydrogen peroxide on the organic phase was studied by IR spectroscopy. No structural changes in TBP were observed after 30 cycles of extraction/stripping; thus, the use of hydrogen peroxide in this application is unrestricted.

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Section: Properties Of Uranium Peroxidesupporting

confidence: 93%

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

et al. 2013

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“…In Table 2, these five crystalline modifications are shown along with several of their properties. The decomposition of ADU at 450-500°C is the mechanism by which β-UO 3 is formed (Hoekstra and Siegel 1961). Since the UO 3 currently in inventory was formed by this method (Burney 1966), the β-UO 3 crystalline modification is of primary interest.…”

Section: Uomentioning

confidence: 99%

“…Since the UO 3 currently in inventory was formed by this method (Burney 1966), the β-UO 3 crystalline modification is of primary interest. The β-UO 3 begins to decompose from the 3.0 U:O ratio at 530°C, but it does not completely convert to the 2.67 U:O ratio of U 3 O 8 until it approaches about 650°C (Hoekstra and Siegel 1961). Since the β-UO 3 predominates the current inventory, a temperature of at least 650°C is needed for conversion to U 3 O 8 .…”

Section: Uomentioning

confidence: 99%

Thermal Stabilization of {sup 233}UO{sub 2}, {sup 233}UO{sub 3}, and {sup 233}U{sub 3}O{sub 8}

Thein¹

2000

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This report identifies an appropriate thermal stabilization temperature for 233 U oxides. The temperature is chosen principally on the basis of eliminating moisture and other residual volatiles. This report supports the U. S. Department of Energy (DOE) Standard for safe storage of 233 U (DOE 2000), written as part of the response to Recommendation 97-1 of the Defense Nuclear Facilities Safety Board (DNFSB), addressing safe storage of 233 U.The primary goals in choosing a stabilization temperature are (1) to ensure that the residual volatiles content is less than 0.5 wt % including moisture, which might produce pressurizing gases via radiolysis during long-term sealed storage; (2) to minimize potential for water readsorption above the 0.5 wt % threshold; and (3) to eliminate reactive uranium species. The secondary goals are (1) to reduce potential future chemical reactivity and (2) to increase the particle size thereby reducing the potential airborne release fraction (ARF) under postulated accident scenarios.

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“…The calculated values of the nuclear scattering length density (SLD) for some common phases in uranium-oxide system. The calculations are based on specific densities published in literature [73,74].…”

Section: Figurementioning

confidence: 99%

Probing Interfaces in Metals Using Neutron Reflectometry

Demkowicz

Majewski

2016

Metals

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Solid-state interfaces play a major role in a variety of material properties. They are especially important in determining the behavior of nano-structured materials, such as metallic multilayers. However, interface structure and properties remain poorly understood, in part because the experimental toolbox for characterizing them is limited. Neutron reflectometry (NR) offers unique opportunities for studying interfaces in metals due to the high penetration depth of neutrons and the non-monotonic dependence of their scattering cross-sections on atomic numbers. We review the basic physics of NR and outline the advantages that this method offers for investigating interface behavior in metals, especially under extreme environments. We then present several example NR studies to illustrate these advantages and discuss avenues for expanding the use of NR within the metals community.

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The uranium-oxygen system: U3O8-UO3

Cited by 175 publications

References 20 publications

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

Uranium stripping from tri-n-butyl phosphate by hydrogen peroxide solutions

Thermal Stabilization of {sup 233}UO{sub 2}, {sup 233}UO{sub 3}, and {sup 233}U{sub 3}O{sub 8}

Probing Interfaces in Metals Using Neutron Reflectometry

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