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已有的研究表明,温度超过元件包壳熔点时,Zr-4合金与蒸汽在包壳表层反应所生成的ZrO_2氧化膜将对Zr-4合金熔融物本身起到一定的保护作用。因此这层氧化膜的厚度及完整性对于由堆芯元件过热及由此引起的Zr-4合金熔融物流动所导致的反应堆事故具有重要的影响。本文假定氧的扩散是ZrO_2氧化膜厚度变化的控制因素,通过解扩散方程,导出了对在这种情况下ZrO_2膜厚度变化的计算公式。
It has been shown that the ZrO 2 oxide film formed by the reaction of Zr-4 alloy with steam on the surface of the cladding will protect Zr-4 alloy melt itself when the temperature exceeds the melting point of the cladding. The thickness and integrity of this oxide film therefore have a significant impact on the reactor accident caused by overheating of the core element and the resulting flow of Zr-4 alloy melt. This paper assumes that the diffusion of oxygen is the controlling factor of ZrO_2 oxide film thickness variation. By calculating the diffusion equation, the formula of ZrO_2 film thickness variation in this case is deduced.