Morphological analysis of uranium materials has proven to be a key signature for nuclear forensic purposes. This study examines the morphological changes to magnesium diuranate (MDU) and sodium diuranate (SDU) during reduction in a 10 % hydrogen atmosphere with and without steam present. Impurity concentrations of the materials were also examined pre and post reduction using energy dispersive X-ray spectroscopy combined with scanning electron microscopy (SEM-EDX). The structures of the MDU, SDU, and UO x samples were analyzed using powder X-ray diffraction (p-XRD). Using this method, UO x from MDU was found to be a mixture of UO2, U4O9, and MgU2O6 while UO x from SDU were combinations of UO2, U4O9, U3O8, and UO3. By SEM, the MDU and UO x from MDU had identical morphologies comprised of large agglomerates of rounded particles in an irregular pattern. SEM-EDX revealed pockets of high U and high Mg content distributed throughout the materials. The SDU and UO x from SDU had slightly different morphologies. The SDU consisted of massive agglomerates of platy sheets with rough surfaces. The UO x from SDU was comprised of massive agglomerates of acicular and sub-rounded particles that appeared slightly sintered. Backscatter images of SDU and related UO x materials showed sub-rounded dark spots indicating areas of high Na content, especially in UO x materials created in the presence of steam. SEM-EDX confirmed the presence of high sodium concentration spots in the SDU and UO x from SDU. Elemental compositions were found to not change between pre and post reduction of MDU and SDU indicating that reduction with or without steam does not affect Mg or Na concentrations. The identification of Mg and Na impurities using SEM analysis presents a readily accessible tool in nuclear material analysis with high Mg and Na impurities likely indicating processing via MDU or SDU, respectively. Machine learning using convolutional neural networks (CNNs) found that the MDU and SDU had unique morphologies compared to previous publications and that there are distinguishing features between materials created with and without steam.

中文翻译：

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重铀酸钠和镁钠还原的铀氧化物的形貌

铀材料的形态分析已被证明是核法证目的的关键特征。本研究考察了在存在和不存在蒸汽的 10% 氢气气氛中还原过程中重铀酸镁 (MDU) 和重铀酸钠 (SDU) 的形态变化。还使用能量色散 X 射线光谱结合扫描电子显微镜 (SEM-EDX) 检查了还原前后材料的杂质浓度。MDU、SDU 和 UO 的结构 X 使用粉末 X 射线衍射 (p-XRD) 分析样品。使用这种方法，UO X 来自 MDU 的物质被发现是 UO 的混合物2,U4氧9, 和 MgU2氧6而UO X 来自 SDU 的组合是 UO2,U4氧9,U3氧8, 和 UO3。通过 SEM、MDU 和 UO X 来自 MDU 的颗粒具有相同的形态，由不规则图案的圆形颗粒大团聚体组成。SEM-EDX 显示整个材料中分布着高 U 和高 Mg 含量的区域。SDU 和 UO X 来自 SDU 的形态略有不同。SDU 由表面粗糙的板状片材的大量团聚体组成。俄勒冈大学 X 来自 SDU 的颗粒由针状和亚圆形颗粒的大块团聚体组成，这些颗粒似乎略有烧结。SDU 和相关 UO 的后向散射图像 X 材料显示出亚圆形黑点，表明 Na 含量高的区域，尤其是 UO X 在蒸汽存在下产生的材料。SEM-EDX 证实 SDU 和 UO 中存在高钠浓度点 X 来自山东大学。发现 MDU 和 SDU 还原前后的元素组成没有变化，表明使用或不使用蒸汽的还原不会影响 Mg 或 Na 浓度。使用 SEM 分析鉴定镁和钠杂质为核材料分析提供了一种易于使用的工具，高镁和钠杂质可能表明分别通过 MDU 或 SDU 进行处理。使用卷积神经网络 (CNN) 的机器学习发现，与之前的出版物相比，MDU 和 SDU 具有独特的形态，并且使用和不使用蒸汽创建的材料之间存在显着特征。