scholarly journals Chemical state mapping of simulant Chernobyl lava-like fuel containing material using micro-focused synchrotron X-ray spectroscopy

2021 ◽  
Vol 28 (6) ◽  
Author(s):  
Hao Ding ◽  
Malin C. Dixon Wilkins ◽  
Lucy M. Mottram ◽  
Lewis R. Blackburn ◽  
Daniel Grolimund ◽  
...  

Uranium speciation and redox behaviour is of critical importance in the nuclear fuel cycle. X-ray absorption near-edge spectroscopy (XANES) is commonly used to probe the oxidation state and speciation of uranium, and other elements, at the macroscopic and microscopic scale, within nuclear materials. Two-dimensional (2D) speciation maps, derived from microfocus X-ray fluorescence and XANES data, provide essential information on the spatial variation and gradients of the oxidation state of redox active elements such as uranium. In the present work, we elaborate and evaluate approaches to the construction of 2D speciation maps, in an effort to maximize sensitivity to the U oxidation state at the U L 3-edge, applied to a suite of synthetic Chernobyl lava specimens. Our analysis shows that calibration of speciation maps can be improved by determination of the normalized X-ray absorption at excitation energies selected to maximize oxidation state contrast. The maps are calibrated to the normalized absorption of U L 3 XANES spectra of relevant reference compounds, modelled using a combination of arctangent and pseudo-Voigt functions (to represent the photoelectric absorption and multiple-scattering contributions). We validate this approach by microfocus X-ray diffraction and XANES analysis of points of interest, which afford average U oxidation states in excellent agreement with those estimated from the chemical state maps. This simple and easy-to-implement approach is general and transferrable, and will assist in the future analysis of real lava-like fuel-containing materials to understand their environmental degradation, which is a source of radioactive dust production within the Chernobyl shelter.

1990 ◽  
Vol 210 ◽  
Author(s):  
C. Lévy-Clèment ◽  
C. Mondoloni ◽  
C. Godart ◽  
R. Cortès

AbstractThis paper presents applications of in situ X-ray diffraction and absorption techniques to the study of H+/MnO2 alkaline batteries. The two complementary in situ techniques are described. Investigation of the electrochemical insertion and deinsertion of H+ has been made through its influence on the evolution of the crystallographic structure of γ-MnO2, while investigation of the transfer of e has been undertaken through the variation of the oxidation state of the manganese during the discharging and charging process of a battery. New insights in the understanding of the mechanisms of proton insertion and charge transfer into γ-MnO2 are discussed.


2007 ◽  
Vol 103 (6) ◽  
pp. 568-571 ◽  
Author(s):  
Yasuhiro Konishi ◽  
Takeshi Tsukiyama ◽  
Norizoh Saitoh ◽  
Toshiyuki Nomura ◽  
Shinsuke Nagamine ◽  
...  

2020 ◽  
Vol 56 (67) ◽  
pp. 9608-9611
Author(s):  
Stephen Bauters ◽  
Andreas C. Scheinost ◽  
Katja Schmeide ◽  
Stephan Weiss ◽  
Kathy Dardenne ◽  
...  

A general strategy for the determination of Tc oxidation state by a new approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3 edge is shown.


1979 ◽  
Vol 25 ◽  
pp. 241-265 ◽  

Pehr Edman died after a short illness at the age of 60 in Munich. His untimely death brought to an end a long and challenging undertaking which although not quite finished to his own satisfaction has brought about a revolution in protein chemistry. Edman’s work has provided chemists with a capability undreamt of a generation ago: the power to determine the amino acid sequence of long runs of peptide chain with speed and precision by an automated method. This has put into man’s grasp essential information for the study of the genetic replication of enzymes and structural proteins and has completed the graduation of protein chemistry from a branch of colloid science to a fundamental organ of molecular genetics. It now seems scarcely necessary to say that the sequencing of proteins, combined with X-ray diffraction analysis, provides a powerful tool to aid the determination of their complete spatial configuration including that of the interface with solvent which carries most of the biological activity. Extension of knowledge of protein sequences is essential in the search for evolutionary relationships between different proteins. In addition, studies of numerous heritable diseases are now showing how aberrant enzymes and structural proteins produced by genetic errors affecting the primary sequence may give rise to the malfunctions observed and how this exact knowledge may sometimes be used to alleviate the condition.


1999 ◽  
Vol 5 (S2) ◽  
pp. 768-769
Author(s):  
J.A. Fortner ◽  
E.C. Buck ◽  
A.J. Kropf ◽  
A.J. Bakel ◽  
M.C. Hash ◽  
...  

We report x-ray absorption near edge structure (XANES) and extended x-ray fine structure analysis (EXAFS) spectra from the plutonium Llll and cerium Lm edges in prototype titanate ceramic hosts for disposal of surplus fissile materials. These spectra were obtained using the MRCAT beamline at the Advanced Photon Source (APS). The XANES and EXAFS results are compared with electron loss spectra (EELS) determination of oxidation state from the plutonium MlV,V and cerium MlV,V edges [1,2]. The titanate ceramics studied are based upon the hafniumpyrochlore and zirconolite mineral structures and will serve as an immobilization host, containing as much as 10 weight % fissile plutonium, and 20 weight % (natural or depleted) uranium. Similar formulations were composed using cerium as a “surrogate” element, replacing both plutonium and uranium in the ceramic matrix. We find the plutonium to be present almost entirely as Pu (IV), while the cerium is clearly in a mixed III-IV oxidation state in the surrogate ceramic.


2011 ◽  
Vol 21 (46) ◽  
pp. 18592 ◽  
Author(s):  
Russell J. Woolley ◽  
Benoit N. Illy ◽  
Mary P. Ryan ◽  
Stephen J. Skinner

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