| Abstract Scope |
Focused ion beam (FIB) methods at Idaho National Laboratory were used to make several thin sections from a low burnup uranium oxide spent fuel. These FIB sections were measured at the oxygen K-edge, uranium N4,5-edges, and cerium M4,5-edges utilizing the scanning transmission x-ray microscope (STXM) at Advanced Light Source Beamline 11.0.2 at Lawrence Berkeley National Laboratory. The oxygen K-edge results were analyzed by non-negative matrix factorization methods and revealed two main components, the bulk of the sample which is made up largely of UO2, and a thin surface layer (~8 nm) of UO2+x resulting from oxidation following sectioning. The measurements show that Ce (~0.4 wt.%) is predominantly trivalent, although a small contribution of tetravalent Ce cannot be ruled out. These results form a foundation for future STXM measurements of spent nuclear fuel FIB sections that can be expanded to mixed-oxide, uranium nitride, and other advanced fuels. |