Rotationally resolved electronic spectra for uranium monoxide

Nicolaï, Jean-Philippe; Riley, S. J.; Parks, E. K.

doi:10.1016/0009-2614(85)80065-8

Cited by 34 publications

(26 citation statements)

References 13 publications

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“…There are no reported solid state pure binary compounds of U oxides, where U cations have a formal oxidation state less than +4; thus, there are no reference lines between U +4 and U 0 from pure compounds. UO is a known compound in the gas phase [22] but no reported XPS U4f lines are known and while U carbides have been studied [23] detailed analyses of the U4f region is not available. 2.…”

Section: Figurementioning

confidence: 99%

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

et al. 2007

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Section: Figurementioning

confidence: 99%

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

et al. 2007

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“…The apparent 4-electron reaction found in the MCE might also be two 2-electron transfer processes, but close to one another. Previous studies 45,46 suggest that UO can exist in equilibrium in the presence of other uranium oxide states. Using the voltammetry information from Fig.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Reduction of UO₂ to U in LiCl-KCl Molten Salt Eutectic Using the Fluidized Cathode Process

et al. 2016

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The electrochemical reduction of UO 2 to U metal has been investigated in both Fluidized Cathode (FC) and Metallic Cavity Electrode (MCE) cell arrangements. Differences in the local concentration of O 2− where the reduction takes place influnces the reduction potential. The fleeting contact of UO 2 particle contact with the current collector in case of the FC results in much less O 2− buildup compared to MCE. Consequently, UO 2 reduction occurs over a range of potentials in the FC and may involve separate two 2-electron steps compared to one apparent 4-electron step in the MCE. It is proposed that there are three discrete periods during the FC reduction process. The first is an induction period during which reduced uranium particles gradually adhere to the tungsten current collector. The second is reduction associated with a rapid growth in electrode area and consequent increase in current. The third is a slower reduction of the remaining oxide in the melt. Complete reduction of metallic U is achieved at −2.2 V (vs. Ag/Ag + ) with an estimated faradaic current efficiency of >92%. There are significant drivers for pursuing the next generation of nuclear reactors. Generation IV reactors offer both advancements in reactor design and also feature fully integrated fuel reprocessing capabilities. There are six types of Generation IV nuclear reactors and power plants under development. These are: the very-high-temperature reactor (VHTR), the sodium-cooled fast reactor (SFR), the supercriticalwater-cooled reactor (SCWR), the gas-cooled fast reactor (GFR), the lead-cooled fast reactor (LFR), and the molten salt reactor (MSR). The key features of each are summarized in Table I. The fuel type used in the majority of these reactors is metal. Given that most current reactors employ metal oxide (MOX or UOX) fuel and the majority of legacy waste is also metal oxide, the conversion of metal oxides to metals is an important component in a future nuclear power flow sheet.High temperature molten salt reprocessing technology (pyroprocessing) 2 for spent nuclear fuel offers a range of advantages when compared to aqueous reprocessing techniques. This is due to: an improved proliferation resistance (local processing reduces the likelihood of material diversion, no separation of plutonium); using facilities with a smaller footprint; a shorter cooling period for irradiated fuel, and also improved criticality safety margins. Different process systems and salts have been studied in pyroprocessing, most of which are summarized by the Nuclear Energy Agency (NEA). Conceptual flow sheets for the pyrochemical treatment of used nuclear fuel are described by Argonne National Lab (ANL). 4 The spent nuclear fuel, in the form of oxide pellets, is decladded and chopped, then passed on for an electrolytic reduction step. The uranium is in the form of UO 2 ; hence, the reduction of UO 2 to U metal is being investigated here. The reduced species then undergo electrorefining, [5][6][7][8][9] where U product and other transuranic species are separated an...

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“…Based solely on the magnitude of its isotope shift, the UO band might not look particularly attractive for isotopic analysis. However, the substantial perturbations in the UO molecular energy levels [36,42] provide some additional unique spectral features that can be exploited for isotopic analysis. To elaborate, because of the large number of electronic states available and the high degree of configuration mixing present in uranium, perturbations in U-bearing molecular energy levels are heavy and frequent [42][43][44].…”

Section: Determination Of Lamis-libs Base Spectra For 235 U and 238 Umentioning

confidence: 99%

“…However, the substantial perturbations in the UO molecular energy levels [36,42] provide some additional unique spectral features that can be exploited for isotopic analysis. To elaborate, because of the large number of electronic states available and the high degree of configuration mixing present in uranium, perturbations in U-bearing molecular energy levels are heavy and frequent [42][43][44]. Heaven et al [42] and Kaledin et al [25,26] found that many UO bands are perturbed to a degree that prevented rotational analysis.…”

Section: Determination Of Lamis-libs Base Spectra For 235 U and 238 Umentioning

confidence: 99%

“…To elaborate, because of the large number of electronic states available and the high degree of configuration mixing present in uranium, perturbations in U-bearing molecular energy levels are heavy and frequent [42][43][44]. Heaven et al [42] and Kaledin et al [25,26] found that many UO bands are perturbed to a degree that prevented rotational analysis. Because the extent of perturbations depends on the specific interactions and mixing of the energy levels, which is isotope dependent, it has been reported that perturbations in UO are different for its isotopologues [43] and the effect of isotopic substitution on the spectrum is so profound that the correlation between bands for the two species cannot be made with any confidence [42].…”

Section: Determination Of Lamis-libs Base Spectra For 235 U and 238 Umentioning

confidence: 99%

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Combination of atomic lines and molecular bands for uranium optical isotopic analysis in laser induced plasma spectrometry

Mao

Chan

Choi

et al. 2017

J Radioanal Nucl Chem

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Rotationally resolved electronic spectra for uranium monoxide

Cited by 34 publications

References 13 publications

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

Electrochemical Reduction of UO₂ to U in LiCl-KCl Molten Salt Eutectic Using the Fluidized Cathode Process

Combination of atomic lines and molecular bands for uranium optical isotopic analysis in laser induced plasma spectrometry

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Rotationally resolved electronic spectra for uranium monoxide

Cited by 34 publications

References 13 publications

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

The reactions of water vapour on the surfaces of stoichiometric and reduced uranium dioxide: A high resolution XPS study

Electrochemical Reduction of UO2 to U in LiCl-KCl Molten Salt Eutectic Using the Fluidized Cathode Process

Combination of atomic lines and molecular bands for uranium optical isotopic analysis in laser induced plasma spectrometry

Contact Info

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Electrochemical Reduction of UO₂ to U in LiCl-KCl Molten Salt Eutectic Using the Fluidized Cathode Process