Quantifying Impurity Effects on the Surface Morphology of α-U₃O₈

Abstract

The morphological effect of impurities on α-U3O8 has been investigated. This study provides the first evidence that the presence of impurities can alter nuclear material morphology, and these changes can be quantified to aid in revealing processing history. Four elements: Ca, Mg, V, and Zr were implemented in the uranyl peroxide synthesis route and studied individually within the α-U3O8. Six total replicates were synthesized, and replicates 1–3 were filtered and washed with Millipore water (18.2 MΩ) to remove any residual nitrates. Replicates 4–6 were filtered but not washed to determine the amount of impurities removed during washing. Inductively coupled plasma mass spectrometry (ICP-MS) was employed at key points during the synthesis to quantify incorporation of the impurity. Each sample was characterized using powder X-ray diffraction (p-XRD), high-resolution scanning electron microscopy (HRSEM), and SEM with energy dispersive X-ray spectroscopy (SEM-EDS). p-XRD was utilized to evaluate any crystallographic changes due to the impurities; HRSEM imagery was analyzed with Morphological Analysis for MAterials (MAMA) software and machine learning classification for quantification of the morphology; and SEM-EDS was utilized to locate the impurity within the α-U3O8. All samples were found to be quantifiably distinguishable, further demonstrating the utility of quantitative morphology as a signature for the processing history of nuclear material.

Progress in Uranium Chemistry: Driving Advances in Front-End Nuclear Fuel Cycle Forensics

“…Building significantly on this potential, several recent studies investigated the morphology of various UOCs using a software program, morphological analysis for materials ( MAMA ), to quantitatively characterize the particles from SEM images. − ,− Olsen et al studied the differences in the morphological features of U 3 O 8 materials produced by calcining α-UO 3 at various temperatures, 600, 650, 700, 750, and 800 °C . While they did observe some qualitative variations among the U 3 O 8 samples produced at the various calcining temperatures, processing the SEM images through the MAMA particle segmentation software enabled a quantitative determination of the morphological statistics for the material.…”

“…In particular, recent research has examined the morphology of various uranium oxides, with a focus on discerning process history or process conditions for a particular sample of material. [20][21][22][23][24][25][26][27][28][29][30][31][32]46 One outcome of these efforts was a lexicon to standardize descriptions of material images for nuclear forensics, indicating a likely increasing role for morphology within nuclear forensics. 33 Recent research has also investigated elemental and chemical impurities present in process samples of uranium compounds, also with a focus of discerning process history as well as the origin of the uranium.…”

“…Over the past decade, a significant research effort has focused on several of these key uranium compounds with the aim of advancing the science of these compounds and the field of nuclear forensics. In particular, recent research has examined the morphology of various uranium oxides, with a focus on discerning process history or process conditions for a particular sample of material. − , One outcome of these efforts was a lexicon to standardize descriptions of material images for nuclear forensics, indicating a likely increasing role for morphology within nuclear forensics . Recent research has also investigated elemental and chemical impurities present in process samples of uranium compounds, also with a focus of discerning process history as well as the origin of the uranium. − ,,,− For example, the concentrations of rare-earth elements (REEs) have been found to be potentially useful for identifying the origin of UOCs .…”

Phase Analysis of Australian Uranium Ore Concentrates Determined by Variable Temperature Synchrotron Powder X-ray Diffraction

“…17 The storage of uranium oxides impacts their surface morphology and methods to link surface morphology to the processing history and storage have been reported. 18,19 The oxidation and hydration of U 3 O 8 can lead to the formation of schoepite phases, thus with time and exposure to moisture, the phase assemblage of a UOC will evolve. 8,20 Schoepite is assumed to easily transition to meta-schoepite under ambient conditions and it has also been shown that metaschoepite can form on the surface of U 3 O 8 when exposed to air and moisture.…”

Determining the Composition of a Mixed Material with Synthetic Data

“…Matson et al (2019) utilized CNNs to categorize structures of carbon nanotubes and nanofibers. Similarly, Hanson et al (2019) and Heffernan et al (2019) also used CNNs for the task of categorizing the characteristics of materials. In addition to using CNNs for the task of classification, CNNs have also been deployed for other tasks such as estimating optimal operational parameters (such as the focus setting) during the image acquisition of scanning electron microscopy (SEM) images (Yang et al, 2020), segmenting structures characterized in SEM images (Ly et al, 2019;Pazdernik et al, 2020), denoising the drifted microscopic images (Vasudevan & Jesse, 2019), and reconstructing sparse SEM images (Trampert et al, 2019).…”