uranium trioxide

Accurate and precise measurement of uranium content in uranium trioxide …

Accurate and precise measurement of uranium content in uranium trioxide by gravimetry: Comparison with isotope dilution mass spectrometry and its uncertainty estimation. ... Nuclear material, such as uranium (U) and plutonium (Pu), accountancy is essential for safeguards purposes in nuclear fuel cycle facility (Magara et al., 2000; …

Density Functional Theory Study of the Thermodynamic and …

Gamma uranium trioxide, γ-UO3, is one of the most important polymorphs in uranium trioxide system, which is common throughout the nuclear fuel cycle and used industrially in the reprocessing of nuclear fuel and uranium enrichment. In this work, a detailed theoretical solid-state density functional theory study of this material was carried …

uranium trioxide

uranium trioxide. Formula: O 3 U; Molecular weight: 286.0271; CAS Registry Number: ; Information on this page: Notes; Other data available: Condensed phase thermochemistry data; Gas phase ion energetics data; Vibrational and/or electronic energy levels; Data at other public NIST sites: X-ray Photoelectron Spectroscopy Database, …

uranium trioxide

uranium trioxide. Formula: O 3 U; Molecular weight: 286.0271; CAS Registry Number: ; Information on this page: Gas phase ion energetics data; References; Notes; Other data available: Condensed phase thermochemistry data; Vibrational and/or electronic energy levels; Data at other public NIST sites: X-ray Photoelectron Spectroscopy ...

Pressure-induced structural and electronic phase transitions of uranium

Pressure-induced structural and electronic phase transitions of uranium ...

Neutron powder profile studies of the gamma uranium trioxide …

Neutron powder profile studies show the existence of three phases in gamma uranium trioxide between 373°K and 77°K. The three phases are closely related and the transitions smooth and displacive. At 373°K, γ-UO 3 is tetragonal, with a = 6.9013 (5) and c = 19.9754 (18) Å, and space group I4 1 amd ( D 19 4h).

uranium trioxide

uranium trioxide. Formula: O 3 U; Molecular weight: 286.0271; CAS Registry Number: ; Information on this page: Condensed phase thermochemistry data; Vibrational and/or electronic energy levels; References; Notes; Other data available: Gas phase ion energetics data; Data at other public NIST sites: X-ray Photoelectron Spectroscopy ...

WebElements Periodic Table » Uranium » uranium …

Formula: UO 3. Hill system formula: O 3 U 1. CAS registry number: [] Formula weight: 286.027. Class: oxide. Colour: orange-yellow. Appearance: crystalline solid. Melting point: (decomposes to U 3 O 8) …

Uranium trioxide and the UO3 hydrates

ε-UO 3 is an exotic polymorph in the uranium trioxide system with an undetermined crystal structure and limited optical vibrational spectroscopic data. To improve understanding of this compound, we synthesize and investigate the crystal structure and optical vibrational spectra of ε-UO 3.Infrared spectra collected for ε-UO 3 are in good agreement with …

Neutron powder profile studies of the gamma uranium trioxide …

Uranium trioxide (UO 3) is a stable chemical form of uranium oxide with multiple polymorphs found throughout the nuclear fuel cycle.The pressure-induced changes in the structure and lattice dynamics of four of these polymorphs are simulated with density functional perturbation theory and analyzed.

Reduction of uranium oxide U3O8 to UO2 by hydrogen

Keywords: uranium trioxide reduction; Kinetic rate; Rate-limiting step Materials: U,0,,; UO, 1. Introduction The reduction by hydrogen of uranium trioxide to uranium dioxide is a gas-solid transformation which occurs during the elaboration of nuclear fuel. In this transformation, the uranium trioxide is first con- verted into the L^Og …

Ab Initio Investigation of the UO3 Polymorphs: …

Uranium trioxide (UO 3) is known to adopt a variety of crystalline and amorphous phases. Here we applied the Perdew–Burke–Ernzerhof functional + U formalism to predict …

The Heat Capacities of Uranium, Uranium Trioxide, and Uranium …

Heat capacity measurements have been made over the temperature range 15–300°K for uranium metal, uranium trioxide, and uranium dioxide. A maximum was observed at 28.7°K in the heat capacity curve of UO2 which is probably the result of the changing population of the magnetic quadrivalent uranium ions among their available energy …

Oxygen Isotopic Composition of U3O8 Synthesized From …

, produced from uranium metal, uranyl nitrate hydrate, and uranium trioxide as starting materials. The results showed that δ18Oof U 3 O 8 is independent of the above-listed starting materials. δ 18O values of 10 synthetic U 3 O 8 were similar (9.35 ± 0.46‰) and did not change as a function of calcination time or calcination temperature. We ...

DESCRIPTION OF AN INSTALLATION FOR THE PRODUCTION OF URANIUM TRIOXIDE

Air is used as a fluidizing medium and is kept at temperatures between 300 and 350 deg C. The aims of the process are to obtain a uranium oxide with sufficient reactivity for subsequent processes and require an adequate control of the size of the oxide particles produced (80 to 400 microns).

First-principles study of elastic and thermodynamic

A detailed solid-state density functional theory study of uranium dioxide (UO 2), gamma uranium trioxide (γ-UO 3), and alpha triuranium octoxide (α-U 3 O 8), which are very common materials throughout the nuclear fuel cycle, was carried out.DFT simulations of these three oxides were presented using both PBE+U and LDA+U …

Investigation of the polymorphs and hydrolysis of …

Uranium trioxide (UO 3) is produced on the front end of the nuclear fuel cycle in the mining, milling, refinement and conversion processes that precede …

Pressure-induced structural and electronic phase transitions of uranium

Uranium trioxide (UO3) is known to adopt a variety of crystalline and amorphous phases. Here we applied the Perdew-Burke-Ernzerhof functional + U formalism to predict structural, electronic, and ...

(PDF) Reduction Kinetics of Uranium Trioxide to Uranium Dioxide …

The conversion process consists in the reduction reaction of uranium trioxide to uranium dioxide according to Equation (1): [5] [6] UO3 + H 2 = UO 2 + H 2 O (1) Figure 3 shows the uranium Pourbaix diagram: According to Figure 3, before the uranium trioxide is reduced to uranium dioxide, it will show up a third oxide species, U3O8.

Accurate and precise measurement of uranium content in uranium trioxide …

1. Introduction. Nuclear material, such as uranium (U) and plutonium (Pu), accountancy is essential for safeguards purposes in nuclear fuel cycle facility (Magara et al., 2000; Alvarez et al., 2000; Donohue, 1998).Tokai Reprocessing Plant (TRP) is the first spent nuclear fuel reprocessing plant in Japan, which adopted Pu and U recovery by …

Uranium oxides structural transformation in human …

Using a combination of methods, a complex examination of structural changes of uranium oxides in the range from UO 2 to U 4 O 9, U 3 O 8 and UO 3 as …

Uranium trioxide and the UO3 hydrates

Uranium trioxide and the UO3 hydrates 1845 Precipitation occurs when polymerization has proceeded to a point where the species is no longer soluble. A UQ hydrate is deposited from aqueous solution and one may envisage this as an hydrated polymer, i.e. a polymer containing double hydroxyl bridges, uo.,/[ "uo., / n The somewhat variable ...

The uranium trioxide-water system

The uranium trioxide-water system 765 hydroxyl groups or water molecules) must determine the decomposition route to be followed even though these differences are not apparent in the X-ray powder patterns. They report variations in dihydrate i.r. spectra to support this con- clusion. Poko et al. [24], after an extensive …

URANIUM TRIOXIDE Definition & Meaning | Dictionary

Uranium trioxide definition: a radioactive orange powder, UO3, used in the manufacture of some ceramics. See examples of URANIUM TRIOXIDE used in a sentence.

Reduction Kinetics of Uranium Trioxide to Uranium Dioxide …

The conversion process consists in the reduction reaction of uranium trioxide to uranium dioxide according to Equation (1): [5] [6] UO32+= H UO 22 + H O (1) Figure 3 shows the uranium Pourbaix diagram: According to Figure 3, before the uranium trioxide is reduced to uranium dioxide, it will show up a third oxide species, U3O8.

Ab Initio Investigation of the UO3 Polymorphs: Structural …

Uranium trioxide (UO 3) is known to adopt a variety of crystalline and amorphous phases.Here we applied the Perdew–Burke–Ernzerhof functional + U formalism to predict structural, electronic, and elastic properties of five experimentally determined UO 3 polymorphs, in addition to their relative stability. The simulations reveal that the …

Investigation of the polymorphs and hydrolysis of …

uranium trioxide species, UO 3, is then reduced to UO 2 and subsequently converted to UF 4 (and ultimately to UF 6)by fluorination prior to isotopic enrichment. The structural phase of UO 3 that is formed as a result of these different production routes is characteristic of the process. With an understanding of the polymorphic nature of UO 3 ...

Localized orbitals of the T-shape of UO 3

Investigations of the interactions of uranium trioxide (UO3) with other species are expected to provide a new perspective on its reaction and bonding behaviors. Herein, we present a combined ...

uranium trioxide

uranium trioxide. Formula: O 3 U; Molecular weight: 286.0271; CAS Registry Number: ; Information on this page: Gas phase ion energetics data; Vibrational and/or …

Unexpected features in the optical vibrational …

The diverse crystal chemistry and resulting variety of optical vibrational (Raman and IR) spectroscopic features of members of the uranium trioxide polymorph system have been of interest to researchers for …