Application of micro-XRF for nuclear materials characterization and problem solving

Abstract

A number of spatially resolved elemental imaging techniques are commonly employed to examine plutonium and other nuclear materials (e.g., scanning electron microscopy). Up until the past 10–15 years, micro-X-ray fluorescence (MXRF) instrumentation had been relatively uncommon, and even currently, it is underutilized for spatially resolved nuclear materials analysis and imaging. In the current study, a number of plutonium materials problem solving applications are presented to demonstrate the power and utility of MXRF for providing unique, spatially resolved elemental composition information. Applications discussed include identification of multiple insoluble fractions in plutonium and neptunium mixed oxide, spatially resolved imaging of plutonium residue and other elements on surface swipes, and spatial mapping of impurities in plutonium metal. The mixed oxide particle analysis demonstrated the ability to non-destructively identify particles of interest for potential extraction and analysis by other methods. The surface swipes study demonstrated the unique ability of MXRF to non-destructively image large multiple cm2 sized, non-conducting, radiologically contaminated samples. The plutonium metal investigation showed the capability of MXRF to non-destructively map elemental heterogeneity directly in an actinide matrix. Such information is extremely valuable prior to using destructive analysis (DA) trace elemental analytical chemistry techniques. If a metal is found to contain significant elemental impurity heterogeneity by MXRF, time consuming destructive sample preparation and analysis do not need to be repeated to confirm that the sample is indeed heterogeneous.