Abstract

In the case of a severe accident at a nuclear power plant with light-water reactors, the most effective method for localization of the formed melt (corium) is its retention in the cooled reactor vessel whose integrity depends on the heat flux from the melt to the vessel. One of the critically important processes in this case is the oxidation of the melt by water vapor or air–vapor mixture, which may significantly increase the heat load on the reactor vessel due to the heat of exothermal reactions of oxidation of reducing agents present in the melt, the decrease in the thickness of the metallic part of the molten pool, and the release of hydrogen, which depend on the oxidation rate. In analysis of the melt oxidation conditions, it is considered that for the generally accepted scenarios of a severe accident, the most realistic situation is the presence of the solid-phase oxide layer (oxide crust) on the melt surface. In these conditions, based on the diffusion model, we propose a dependence for calculating the oxidation rate for the corium melt and its validation using the obtained experimental data.

中文翻译：

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熔体表面上存在氧化皮的熔融皮质氧化建模

摘要

在带有轻水反应堆的核电站发生严重事故的情况下，对形成的熔体（皮质）进行定位的最有效方法是将其保留在冷却的反应堆容器中，其完整性取决于从熔体流向熔体的热通量。血管。在这种情况下，至关重要的过程之一是水蒸气或空气-蒸气混合物对熔体的氧化，由于存在于反应堆中的还原剂的氧化反应会发生放热反应，这可能会显着增加反应堆容器的热负荷。熔化，熔池金属部分厚度的减少以及氢的释放，这取决于氧化速率。在分析熔体氧化条件时，考虑到对于严重事故的普遍接受的情况，最现实的情况是在熔体表面上存在固相氧化物层（氧化皮）。在这些条件下，基于扩散模型，我们提出了一种依赖关系，用于计算皮质熔体的氧化速率，并使用获得的实验数据对其进行验证。