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Analysis of Th and U in thorium-based mixed-oxide fuel using wavelength dispersive X-ray fluorescence spectrometer
摘要： A precise and accurate compositional characterization methodology using wavelength dispersive X-ray fluorescence (WDXRF) spectrometry for mixed oxide nuclear fuels is reported. The methodology involves pelletization of standards and samples. The calibration plots were made by plotting the percent intensity of analyte X-ray lines against their amount percent. The relative standard deviation were 0.4% and 0.25%, respectively for uranium and thorium, having U ranging from 2.85 to 4.2 (wt%). The analytical results were compared with chemical analysis method and were in good agreement. The developed WDXRF method is non-destructive, fast and better in comparison to chemical analysis methods.
关键词： Thorium,Uranium,WDXRF,Nuclear fuel,Mixed oxides
更新于2025-09-19 17:15:36
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Time-resolved imaging of atoms and molecules in laser-produced uranium plasmas
摘要： Gas-phase oxidation of uranium (U), plume chemistry, and the corresponding impact on optical emission features of the U plasma are investigated. Plasmas were produced via nanosecond laser ablation of a natural U target in a chamber where U oxidation was controlled by varying the oxygen partial pressure in an argon cover gas. Monochromatic imaging of U atoms and monoxide (UO) molecules was performed using narrow bandpass optical filters. Results reveal the spatio-temporal evolution of atomic and molecular species in the plasma. U oxides are found to be formed further from the target (in comparison to U atoms), where lower temperatures favor molecular recombination. Segregation between the distribution of U atoms and UO species is observed at later times of plasma evolution, and is more apparent at lower oxygen partial pressures. At higher oxygen partial pressures, significant variation in plume morphology is noticed for UO species, which can be attributed to the higher oxide (UxOy) formation further from the target. The monochromatic images of U atoms and UO molecules and corresponding spectral features at various oxygen partial pressures presented here provide unique insight into gas-phase, high-temperature U oxidation and chemistry, with implications for a wide range of nuclear applications, from stand-off detection of radioisotopes to forensics and safeguards.
关键词： optical emission spectroscopy,plasma,uranium,laser ablation,monochromatic imaging
更新于2025-09-16 10:30:52
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The preparation and properties of the C-doped modified layers on uranium surfaces by pulsed laser irradiating
摘要： The C-doped modi?ed layer on uranium surface was prepared by pulsed laser irradiating in methane atmosphere. The microstructure of the obtained layer was characterised by X-ray diffraction (XRD), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The results show that the obtained layer is a composite layer with a gradual transition structure from UO2/free carbon to UO2-x/UCxOy/free carbon to UC1-xOy/UC, and eventually to metallic U. To investigate the oxidation mechanism of the C-doped modi?ed layer, initial oxidation behavior of O-rich surface and O-poor surface obtained after sputtering for 7 min and 60 min were studied by XPS. And the results illustrate that UCxOy with U 4f7/2 binding energy at 379.5 eV in the O-rich region is more resistant to oxidation than UC1-xOy/UC under oxygen exposure. Free carbon is distributed in the surface layer of C-doped modi?ed layer prepared by pulsed laser irradiating, and the free carbon is also formed after oxidation of UC1-xOy, UC and UCxOy at room temperature. We speculate that the aggregation of free carbon increases the ability to prevent the inward diffusion of O atoms. Moreover, the results of the potentiodynamic polarization tests show that the C-doped modi?ed layer improved the corrosion protective properties of metallic U. The self-corrosive potential and self-corrosive current of the C-doped modi?ed layer are ?1.47 × 10?1 V vs. SCE and 9.46 × 10?8 A/cm2, respectively, while the values of metallic U are ?5.67 × 10?1 V vs. SCE and 8.08 × 10?7 A/cm2, respectively.
关键词： Microstructure,Uranium oxy-carbide,Pulsed laser modi?cation,Oxidation behavior,Uranium C-Doped modi?ed layer
更新于2025-09-11 14:15:04
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Assessing UO2 sample quality with μ-Raman spectroscopy
摘要： m-Raman spectroscopy of UO2 has demonstrated its value as a tool in nuclear forensics and for analyzing nuclear fuels, but its ability to evaluate UO2 sample quality has been relatively unexplored. To investigate this potential, a three-pronged study that uses Raman spectroscopy to analyze 1) three distinct qualities of UO2 single crystals with two different excitation lasers, 2) a high quality single crystal UO2 sample that is progressively damaged with a laser, and 3) a single crystal of UO2 grown on top of a ThO2 substrate was undertaken. The results demonstrate that the peak height ratio between the second order longitudinal optical phonon signal near 1145 cm?1 and the T2g peak located near 450 cm?1 is directly correlated with crystal quality when a 532 nm excitation source is used. Furthermore, this observed pattern relies upon the two most intense peaks that are present in the Raman spectra, making it more robust to lower signal-to-noise ratios than similar trends present in the peak height ratio between the first order longitudinal optical phonon signal near 565 cm?1 and the T2g peak. Both peak height ratios are more sensitive indicators of the crystal quality than the width ratios of the same signals or the associated wavenumber shift in the T2g peak location. The correlation between the 2LO and T2g peak heights and the overall crystal quality offers the potential to directly assess and compare the quality of different samples of single crystal UO2.
关键词： Uranium dioxide,Sample quality,m-Raman spectroscopy,UO2,Single crystal
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) PHYSICS, TECHNOLOGIES AND INNOVATION (PTI-2018): Proceedings of the V International Young Researchers’ Conference - Ekaterinburg, Russia (14–18 May 2018)] - Reduction of uranium(VI) species in alkali chloride melts: An electronic absorption spectroscopy study of formation of uranium(V) ions
摘要： Reaction of uranyl chloride with gaseous hydrogen was studied in a range of alkali chloride based melts between 350 and 850 oC. The reaction leads to the formation of soluble uranium(V) dioxochloro-species and solid uranium dioxide. In situ electronic absorption spectroscopy was employed to follow the reaction. Electronic absorption spectra of uranium(V) dioxo-species were recorded between 300 and 1600 nm. The effect of temperature and second coordination sphere cations on the absorption spectra is discussed.
关键词： alkali chloride melts,hydrogen reduction,uranium(V),electronic absorption spectroscopy,uranyl chloride
更新于2025-09-09 09:28:46
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - L X-ray relative intensity ratios of uranium, lead, hafnium and samarium
摘要： In this study the L shell X-ray relative intensities ((cid:1835)(cid:3013)(cid:3287)(cid:512)(cid:1835)(cid:3013)(cid:3330), (cid:1835)(cid:3013)(cid:3328)(cid:512)(cid:1835)(cid:3013)(cid:3330) and (cid:1835)(cid:3013)(cid:3329)(cid:512)(cid:1835)(cid:3013)(cid:3330)) for uranium, lead, hafnium and samarium have been measured for several scattering angles (85°, 95°, 105°, 115°, 125° and 135°) at 59.54 keV photon energy by using a Si(Li) detector which has a resolution of 160 eV at 5.9 keV. In previous studies, the (cid:1838)(cid:3082) X-rays were usually found independ on the scattering angles, therefore we found reasonable to give the ratio to the (cid:1838)(cid:3082) X-rays.
关键词： L X-ray,samarium,relative intensity ratios,uranium,lead,hafnium,scattering angles
更新于2025-09-04 15:30:14