X‐Ray Spectroscopy in Studies of the Nuclear Fuel Cycle

Denecke, Melissa A.

doi:10.1002/9781118844243.ch19

Cited by 3 publications

(1 citation statement)

References 71 publications

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“…X-ray absorption spectroscopy (XAS) is particularly advantageous to probe the electronic structure and the local structure of actinide materials by means of X-ray absorption near the edge structure (XANES) and the extended X-ray absorption fine structure (EXAFS). In addition, the penetrating nature of X-rays in the 3e20 keV energy range, that is, actinide's M 4,5 -and L 3 -edges, allows us to analyze confined samples, avoiding risks of radionuclide dispersion; also, the use of synchrotron radiation limits the masses of the samples that are investigated [13]. However, considering the broadening of XANES spectra due to core-hole lifetime effects, the observation of very fine details can be limited.…”

Section: Introductionmentioning

confidence: 99%

New insight in the uranium valence state determination in U Nd1−O2±

Bès

Kvashnina

Rossberg

et al. 2018

Journal of Nuclear Materials

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The charge compensation mechanisms in U y Nd 1Ày O 2±x and its consequence on the overall O stoichiometry (or O/M ratio where M ¼ Nd þ U) have been studied through the uranium valence state mixture evolution as a function of Nd content up to y ¼ 0.62 by means of high energy resolution fluorescence detection X-ray absorption spectroscopy (HERFD-XAS) at the U M 4-edge. Our results clearly demonstrate the formation of U 5þ at low Nd content (y < 0.15). Upon increasing the Nd content, oxygen vacancies and the formation of U 6þ appear as competing mechanisms for intermediate Nd concentrations, leading to the coexistence of U 4þ /U 5þ /U 6þ mixed valence and an overall hypostoichiometry (O/M < 2.00). Finally, the formation of U 6þ associated with strongly distorted U local environment is observed for high Nd concentrations (y ¼ 0.62), leading to an overall hyperstoichiometry (O/M < 2.00).

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Section: Introductionmentioning

confidence: 99%

New insight in the uranium valence state determination in U Nd1−O2±

Bès

Kvashnina

Rossberg

et al. 2018

Journal of Nuclear Materials

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CAT-ACT—A new highly versatile x-ray spectroscopy beamline for catalysis and radionuclide science at the KIT synchrotron light facility ANKA

Zimina

Dardenne

Denecke

et al. 2017

Review of Scientific Instruments

100

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CAT-ACT-the hard X-ray beamline for CATalysis and ACTinide/radionuclide research at the KIT synchrotron radiation facility ANKA-is dedicated to X-ray spectroscopy, including "flux hungry" photon-in/photon-out and correlative techniques and combines state-of-the-art optics with a unique infrastructure for radionuclide and catalysis research. Measurements can be performed at photon energies varying between 3.4 keV and 55 keV, thus encompassing the actinide M- and L-edge or potassium K-edge up to the K-edges of the lanthanide series such as cerium. Well-established X-ray absorption fine structure spectroscopy in transmission and fluorescence detection modes is available in combination with high energy-resolution X-ray emission spectroscopy or X-ray diffraction techniques. The modular beamline design with two alternately operated in-line experimental stations enables sufficient flexibility to adapt sample environments and detection systems to many scientific challenges. The ACT experimental station focuses on various aspects of nuclear waste disposal within the mission of the Helmholtz association to contribute to the solution of one of the greatest scientific and social challenges of our time-the safe disposal of heat producing, highly radioactive waste forms from nuclear energy production. It augments present capabilities at the INE-Beamline by increasing the flux and extending the energy range into the hard X-ray regime. The CAT experimental station focuses on catalytic materials, e.g., for energy-related and exhaust gas catalysis. Characterization of catalytically active materials under realistic reaction conditions and the development of in situ and operando cells for sample environments close to industrial reactors are essential aspects at CAT.

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A spectroscopic hike in the U–O phase diagram

Prieur¹,

Desagulier²,

Guéneau³

et al. 2021

J Synchrotron Rad

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The U–O phase diagram is of paramount interest for nuclear-related applications and has therefore been extensively studied. Experimental data have been gathered to feed the thermodynamic calculations and achieve an optimization of the U–O system modelling. Although considered as well established, a critical assessment of this large body of experimental data is necessary, especially in light of the recent development of new techniques applicable to actinide materials. Here we show how in situ X-ray absorption near-edge structure (XANES) is suitable and relevant for phase diagram determination. New experimental data points have been collected using this method and discussed in regard to the available data. Comparing our experimental data with thermodynamic calculations, we observe that the current version of the U–O phase diagram misses some experimental data in specific domains. This lack of experimental data generates inaccuracy in the model, which can be overcome using in situ XANES. Indeed, as shown in the paper, this method is suitable for collecting experimental data in non-ambient conditions and for multiphasic systems.

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X‐Ray Spectroscopy in Studies of the Nuclear Fuel Cycle

Cited by 3 publications

References 71 publications

New insight in the uranium valence state determination in U Nd1−O2±

New insight in the uranium valence state determination in U Nd1−O2±

CAT-ACT—A new highly versatile x-ray spectroscopy beamline for catalysis and radionuclide science at the KIT synchrotron light facility ANKA

A spectroscopic hike in the U–O phase diagram

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