Selenium redox speciation and coordination in high-burnup UO2 fuel: Consequences for the release of 79Se in a deep underground repository

The chemical state of Se in high-burnup UO2 spent nuclear fuel (SNF) was investigated by micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. The data were first evaluated in terms of linear combination fits of reference compounds. In a second step, the XANES data were fitted to theore...

Full description

Saved in:
Bibliographic Details
Published in:Journal of nuclear materials 2014-10, Vol.453 (1-3), p.98-106
Main Authors: Curti, Enzo, Froideval-Zumbiehl, Annick, Günther-Leopold, Ines, Martin, Matthias, Bullemer, Andrej, Linder, Hanspeter, Borca, Camelia N., Grolimund, Daniel
Format: Article
Language:English
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The chemical state of Se in high-burnup UO2 spent nuclear fuel (SNF) was investigated by micro X-ray absorption near-edge structure (μ-XANES) spectroscopy. The data were first evaluated in terms of linear combination fits of reference compounds. In a second step, the XANES data were fitted to theoretical (ab initio) spectra via geometrical optimization of atomic clusters around a central Se atom, using the FDMNES and FitIt software packages. Best fits were obtained assuming substitution of Se in occupied or vacant oxygen sites within the UO2 lattice, with 20–25% local expansion. Based on these results and chemical arguments we argue that the long-lived fission product 79Se may be stabilized to sparingly soluble Se(−II) in SNF. This would explain the failure to detect dissolved Se in SNF leaching experiments.
ISSN:0022-3115
1873-4820
DOI:10.1016/j.jnucmat.2014.07.003