First-principles study of diffusion behaviors of Cs and I in Cr coating

分类： 核科学技术 >> 核材料与工艺技术 提交时间： 2024-03-13

Shuying Lin Xiaojing Li Linbing Jiang Xijun Wu Huiqin Yin Yu Ma Wenguan Liu

摘要： Cs and I can migrate through the fuel-cladding interface and accelerate the cladding corrosion process induced by the Fuel Cladding Chemical Interaction. Cr coating is an important candidate in mitigating this chemical interaction. First-principles calculations were employed to investigate the diffusion behaviors of Cs and I in Cr bulk and Cr grain boundary, aiming to reveal the microscopic mechanisms for mitigating the interaction at fuel-cladding interface. The interactions between these two fission products and Cr coating were systematically studied, and the temperature-dependent diffusion coeffcients of Cs and I in Cr were obtained using Bocquet’s oversized solute atoms model and Le Claire’s nine-frequency model, respectively. The results show that the migration barriers of Cs and I are significantly lower compared to that of Cr, and the diffusion coeffcients of Cs and I are both more than 3 orders of magnitude larger than Cr self-diffusion coeffcient within the temperature range of Generation IV fast reactors (below 1000 K), which shows the strong penetration ability of Cs and I. Meanwhile, Cs and I are more likely to diffuse along the grain boundary because of the generally low migration barriers, indicating that grain boundary serves as a fast diffusion channel for Cs and I.

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