Zirconium alloys are extensively used as cladding material in nuclear reactors. They are vulnerable to hydrogen degradation under the harsh service conditions of the reactors. Optical micrographs taken in some pressure tubes shows the presence of hydride denuded zones closer to the surface, where the hydrides formed in this region are smaller in size compared to the bulk. We investigated the effect of oxygen on diffusivity of hydrogen in α Zr, to check the hypothesis that oxygen slows the diffusion of hydrogen and thereby encourages the occurrence of hydride denuded zones. We used a multi-scale model to simulate H diffusion in Zr with different O concentrations to identify the effect that O has on H diffusivity. From the study we found that oxygen indeed decreases the diffusivity of hydrogen in α Zr for moderate oxygen concentrations. We investigated the diffusion processes of individual H atoms, which showed that the reduction in diffusivity is caused by a decrease in the hoppi...

中文翻译：

---

锆压力容器中的裸露区域：通过多尺度扩散模型检验了氧气的作用

锆合金被广泛用作核反应堆的包层材料。它们在反应器的苛刻使用条件下很容易发生氢降解。在某些压力管中拍摄的光学显微照片显示，氢化物的裸露区域靠近表面，与该区域相比，该区域中形成的氢化物尺寸较小。我们研究了氧对αZr中氢扩散率的影响，以检验氧减慢氢扩散从而促进氢化物剥蚀区发生的假设。我们使用了多尺度模型来模拟Z在不同O浓度下的H扩散，以确定O对H扩散率的影响。从研究中我们发现，在中等氧气浓度下，氧气确实会降低αZr中氢气的扩散率。