Grain boundary self-diffusion and point defect interactions in α-U via molecular dynamics

IF 2.8 2区工程技术 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Nuclear Materials Pub Date : 2024-11-19 DOI:10.1016/j.jnucmat.2024.155521

Khadija Mahbuba , Benjamin Beeler , Andrea Jokisaari

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引用次数: 0

Abstract

Though metallic U-Zr fuel has been used in nuclear reactors since the 1960s, many of its fundamental and thermodynamic properties are still unknown. The α-U phase, which has a highly anisotropic crystal structure and physical properties, is present in U-Zr fuel. The character and behavior of α-U grain boundaries will strongly impact fuel thermophysical performance under irradiation. We study the interaction of point defects with grain boundaries, diffusion along grain boundaries, and the predicted diffusional creep behavior of α-U via molecular dynamics. We calculate the segregation energy of vacancies and interstitials to grain boundaries and quantify the biased sink strength of the grain boundaries, and observe that this sink strength is not strongly dependent on the grain boundary orientation. We also find that grain boundary diffusivity is strongly dependent on the grain boundary energy and grain boundary orientation. The presence of point defects within the grain boundary can induce diffusion in grain boundaries with low formation energies and can enhance diffusion in high-energy grain boundaries. We also find that diffusional creep of α-U at prototypical metallic fuel operation conditions is extremely high and could help explain observed metallic fuel swelling behaviors.

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通过分子动力学分析 α-U 中的晶界自扩散和点缺陷相互作用

尽管 U-Zr 金属燃料自 20 世纪 60 年代以来一直用于核反应堆，但其许多基本特性和热力学特性仍不为人知。U-Zr 燃料中存在具有高度各向异性晶体结构和物理性质的 α-U 相。α-U晶界的特征和行为将对燃料在辐照下的热物理性能产生重大影响。我们研究了点缺陷与晶界的相互作用、沿晶界的扩散以及通过分子动力学预测的 α-U 扩散蠕变行为。我们计算了空位和间隙到晶界的偏析能，量化了晶界的偏沉强度，并观察到这种偏沉强度与晶界取向没有很大关系。我们还发现，晶界扩散性与晶界能量和晶界取向密切相关。晶界内点缺陷的存在会诱导低形成能量晶界的扩散，并增强高能量晶界的扩散。我们还发现，在原型金属燃料运行条件下，α-U 的扩散蠕变非常高，这有助于解释观察到的金属燃料膨胀行为。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Nuclear Materials 工程技术-材料科学：综合

CiteScore

5.70

自引率

25.80%

发文量

601

审稿时长

63 days

期刊介绍： The Journal of Nuclear Materials publishes high quality papers in materials research for nuclear applications, primarily fission reactors, fusion reactors, and similar environments including radiation areas of charged particle accelerators. Both original research and critical review papers covering experimental, theoretical, and computational aspects of either fundamental or applied nature are welcome. The breadth of the field is such that a wide range of processes and properties in the field of materials science and engineering is of interest to the readership, spanning atom-scale processes, microstructures, thermodynamics, mechanical properties, physical properties, and corrosion, for example. Topics covered by JNM Fission reactor materials, including fuels, cladding, core structures, pressure vessels, coolant interactions with materials, moderator and control components, fission product behavior. Materials aspects of the entire fuel cycle. Materials aspects of the actinides and their compounds. Performance of nuclear waste materials; materials aspects of the immobilization of wastes. Fusion reactor materials, including first walls, blankets, insulators and magnets. Neutron and charged particle radiation effects in materials, including defects, transmutations, microstructures, phase changes and macroscopic properties. Interaction of plasmas, ion beams, electron beams and electromagnetic radiation with materials relevant to nuclear systems.