Raman and XPS characterization of fuel–cladding interactions using miniature specimens

A combination of laser Raman spectroscopy and X-ray photoelectron spectroscopy was applied in a study of fuel–cladding chemical interactions on miniature oxide-coated HT-9 disks at elevated temperature. The experiments were intended as a preliminary step toward the development of a quick-screening technique for candidate alloys for cladding materials and actinide-based mixed oxide fuel mixtures. The results indicated that laser Raman spectroscopy was capable of determining the major oxides on HT-9 and how they changed in composition due to heating. However, X-ray photoelectron spectroscopy was necessary to identify the role of the metallic phases and provide depth resolution. Using the two techniques the kinetics of chromia growth were shown to be affected by the presence of an applied oxide coating. A single replacement reaction involving residual reduced metal within the coating was also identified.