The intent of this paper is to interrogate the physical characteristics of PuO₂ powders and aggregates produced by direct metal oxidation to examine possible relationships between process parameters and the physical characteristics of the product. The majority of the PuO₂ samples considered were generated during the pre-production and production phases of the Advanced Recovery and Integrated Extraction System (ARIES) program at Los Alamos National Laboratory (LANL). Oxide formed passively on Pu metal surfaces at ambient atmospheric conditions is also characterized. Plutonium oxide powders from the ARIES Direct Metal Oxidation (DMO) furnace and muffle furnace process lines are very consistent in terms of their bulk and tapped density, specific surface area (SSA) and particle size distribution (PSD). The SSAs of calcined PuO₂ generated in the ARIES DMO-2 and muffle furnaces are between 0.1 and 0.5 m²/g. Oxides from both the DMO-2 and muffle furnaces also had similar tri-modal PSDs with maxima at 0.73–3.16 μm, 10.9–18.5 μm, and 41.3–63.0 μm. The PSDs of the oxide formed passively on Pu metal surfaces at ambient conditions were unimodal, with near-Gaussian distributions and D₅₀ close to 1 μm. The oxide formed passively at ambient conditions also had significantly higher SSAs (6–8 m²/g).

A documented process upset that originated from a heater element failure in DMO-2 resulted in significantly lower oxidation temperatures, and produced oxide having a slightly greater SSA, and lower bulk and tapped densities. Macroscopic (by quantitative sieving) and microscopic (by laser diffraction of aqueous suspensions) PSDs of the oxide produced during this interval are characterized by depleted large-diameter particle populations. We speculate that the lack of large particles in the aggregate emerging from DMO-2 during the temperature anomaly reflects a change in the thermal regime during oxidation which favors the generation of finer-grained aggregate.

本文旨在探讨直接金属氧化法制得的PuO ₂粉末和聚集体的物理特性，以检验工艺参数与产品物理特性之间的可能关系。大多数的PuO ₂所考虑的样品是在洛斯阿拉莫斯国家实验室（LANL）的高级回收和综合提取系统（ARIES）计划的生产前和生产阶段生产的。还表征了在环境大气条件下在Pu金属表面上被动形成的氧化物。来自ARIES直接金属氧化（DMO）炉和马弗炉生产线的氧化lu粉末在其堆积密度和堆积密度，比表面积（SSA）和粒度分布（PSD）方面非常一致。在ARIES DMO-2和马弗炉中产生的煅烧PuO ₂的SSA在0.1和0.5 m ^2之间/G。DMO-2和马弗炉的氧化物也具有相似的三峰PSD，最大值分别为0.73-3.16μm，10.9-18.5μm和41.3-63.0μm。在环境条件下被动地在Pu金属表面上形成的氧化物的PSD是单峰的，具有接近高斯分布，D ₅₀接近1μm。在环境条件下被动形成的氧化物也具有较高的SSA（6-8 m ² / g）。

由DMO-2中的加热器元件故障引起的过程不正常的记录表明，氧化温度大大降低，并且生成的氧化硅的SSA略高，堆积密度和堆积密度更低。宏观（通过定量筛分）和微观（通过水悬浮液的激光衍射）在此间隔期间产生的氧化物的PSDs的特征是大直径颗粒群的减少。我们推测，温度异常期间DMO-2产生的聚集体中没有大颗粒，这反映了氧化过程中热态的变化，这有利于生成更细的聚集体。