CHARACTERIZATION AND IDENTIFICATION OF ACTINIDE BEARING MINERALS AND SOILS USING VARIOUS ANALYTICAL TECHNIQUES FOR SIGNATURE DISCOVERY

Toya Nicole Beiswenger

Unique identifying characteristics of actinide bearing minerals and soils can vary depending on the surrounding environment. Many analytical techniques for characterization and identification such as Secondary Ion Mass Spectrometry (SIMS), X-Ray Diffraction (XRD), and X-Ray Fluorescence (XRF) have been utilized for soil and mineral analysis. These techniques aid in gaining insight into a material’s chemical make-up, morphology, and particle size to determine its behavior under various environmental conditions, and potentially provide information on the history of the soil and/or the contaminants within it. \nThis research determined signatures within uranium- and plutonium- rich minerals and soils that could be used to differentiate characteristics that are unique from its surrounding environment. The complexity and heterogeneity of minerals and soils in general posed a challenge to this research, but it also helped reveal the unique traits about the sample. We first investigated uranium rich minerals and soils using Fourier transfer infrared spectroscopy coupled with statistical analyses to determine whether the mid-infrared or the visible-near infrared regions of the electromagnetic spectrum contained useful signatures and if particle size and morphology affected the signatures within those regions. By using statistical analyses such as classical least squares we were able to build dendrograms and visually distinguish groups of minerals from each other. This work progressed with other analytical tools and plutonium-rich soils; this portion of the work took an atomic view of a Pu particle, in turn gaining insight to the chemical behavior within and how the surrounding environment of the Hanford site played a part in its behavior. This was the very first application of a technique called atom probe tomography to a Pu particle. We were able to view the atoms the sample was composed of and illustrated the possible migration of a grain boundary over time and how that information can be used for remedial solutions in the future. \nThe results have shown how the characteristics of a sample (size, morphology, speciation, chemical behavior, etc.) can be used as a discriminator when looking for unique signatures among the complex background associated with soils and minerals, and also be used as a way to better understand how to help remediate contaminated sites with similar chemical makeup as the soils and minerals used in this study.

CHARACTERIZATION AND IDENTIFICATION OF ACTINIDE BEARING MINERALS AND SOILS USING VARIOUS ANALYTICAL TECHNIQUES FOR SIGNATURE DISCOVERY

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