Analytical electron microscopy of light-water reflector fuels

Archetypal spent fuels from commercial light-water reactors (LWRs) are being analyzed by the Materials Characterization Center (MCC) to provide well characterized material for use in spent-fuel testing programs conducted by the U.S. Department of Energy Office of Civilian Radioactive Waste Management Program. Among the characterization methods being used, analytical transmission electron microscopy (AEM) and scanning Auger electron microscopy (SAM) uniquely provide information about the chemical nature and distribution of fission products at sub-micrometer resolution. Burnup-induced changes in microstructure that may affect the oxidation and leaching behavior of LWR fuels are not observable by most other methods. This paper focuses on AEM and SAM of fission-product aggregates (particles and gas bubbles) observed within UO2 grains and along grain boundaries