Traditional nuclear forensic analysis techniques currently have a limited capability to determine the historical storage conditions of interdicted materials. A material of interest, uranium trioxide, is known to react with atmospheric moisture to form several hydrated species. The speciation and extent of hydrate formation is primarily dependent on the storage temperature, exposure time, and relative humidity of the sample’s environment. In this application, the morphological and microstructural properties of amorphous-UO3, under controlled storage conditions, are being investigated using powder X-ray diffraction (p-XRD) and scanning electron microscopy (SEM). These techniques are being utilized to identify quantitative signatures that are indicative of the storage process history for UO3 samples. The high-resolution SEM images acquired are statistically compared using Morphological Analysis for Material Attribution (MAMA) software developed at Los Alamos National Laboratory. Quantitative XRD will be utilized to determine the composition of the hydrated UO3 samples. The utility of the surface morphology and microstructure for assessing process history cannot be realized without a fundamental understanding of the impact of post-synthesis storage conditions. In this study, high-purity amorphous-UO3 is synthesized from the thermal decomposition of uranyl peroxide. Additionally, saturated salt solutions are employed to maintain controlled relative humidities in the storage vessels over the course of the study. The impact of the storage temperature and relative humidity over time will be statistically evaluated as potential sources of morphological variation utilizing the generation of a statistically rigorous multivariate response surface model.

Impact of controlled storage conditions on the hydration and morphology of UO3

254th National Meeting (2017)

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