ABSTRACT Emphasis has been placed on the behavior of ruthenium (Ru) in the evaporation to dryness accident due to the loss of cooling functions (EDLCF) of high-level liquid waste in fuel reprocessing plants. It is because Ru would form volatile compounds such as ruthenium tetroxide (RuO4) and could be released into the environment with other coexisting gasses such as nitric acid (HNO3), water (H2O). To contribute to the safety evaluation of this accident, we experimentally evaluated the decomposition and chemical change behavior of the gaseous RuO4 (RuO4(g)) under the various atmospheric conditions: temperature and composition of coexisting gasses. As a result, the behavior of the RuO4(g) was diverse depending on the atmospheric conditions. In the experiments with the dry air or H2O vapor, decomposition of RuO4(g) was observed. In the experiment with the mixed gas which containing HNO3, almost no decomposition of the RuO4(g) was observed, and chemical form of the RuO4(g) was retained.

中文翻译：

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大气条件下气态四氧化钌的分解行为假设高放废液蒸发干化事故

摘要 由于燃料后处理厂中高放废液失去冷却功能 (EDLCF)，钌 (Ru) 在蒸发至干事故中的行为受到了关注。这是因为 Ru 会形成四氧化钌 (RuO4) 等挥发性化合物，并可能与硝酸 (HNO3)、水 (H2O) 等其他共存气体一起释放到环境中。为了有助于此次事故的安全评估，我们通过实验评估了气态 RuO4 (RuO4(g)) 在各种大气条件下的分解和化学变化行为：温度和共存气体的成分。结果，RuO4(g) 的行为因大气条件而异。在干燥空气或 H2O 蒸汽的实验中，观察到 RuO4(g) 的分解。