Modelling Uranium Corrosion by Hydrogen and Formation of Uranium Hydride

核燃料的长期储存需要专门的储存条件，以确保人类和环境安全。有些含铀金属的废物流，例如存放在塞拉菲尔德的镁诺克斯燃料，在乏燃料后处理之前要进行长期储存。在金属的储存过程中，氢化铀的形成是一种公认的危险，具有许多潜在的问题，包括自燃材料的形成和金属-氢化物界面引入的机械应力。无论铀金属的外层是否被氧化成铀氧化物，都可以形成氢化物，因为氢通过氧化物层。了解核燃料的长期老化是至关重要的，虽然控制氢对金属的腐蚀以及由此产生的氢化物的结构和性质是解决长期储存安全问题的根本，但样品的放射性阻碍了对这种系统的实验研究，使建模技术成为研究金属氢化物界面的宝贵工具。我们将研究金属铀和氢化物之间的界面的结构和性质，使用整体建模方法，结合不同长度尺度的计算。为了通过确定金属-氢化物界面的结构细节及其与界面处的机械应力和反应性的关系来提高乏燃料在储存期间的安全性。我们的目标是提供（1）氢化物在金属上形成的早期阶段的原子模型，（2）氢通过由氧腐蚀金属而形成的氧化物层的渗透，以及（3）金属-氢化物和金属-氧化物界面处的缺陷化学。

Long-term storage of nuclear fuel requires specialist storage conditions, for both human and environmental safety. Some waste-streams containing uranium metal, e.g. Magnox fuel held at Sellafield, undergo long-term storage before spent fuel reprocessing. During the storage of the metal, the formation of uranium hydride is a recognized hazard, with many potential issues, including the formation of the pyrophoric material and the mechanical stress introduced by the metal-hydride interfaces. The hydride can form whether or not the outer layer of the uranium metal has been oxidized to uranium oxide, as hydrogen percolates through the oxide layer. Understanding the long-term ageing of the nuclear fuel is of vital importance and although the control over the corrosion of the metal by hydrogen and the structure and properties of the resulting hydride are fundamental to addressing the safety concerns of long-term storage, experimental investigation of such systems is hindered by the radioactivity of the samples, making modelling techniques invaluable tools for studying the metal-hydride interface. We will investigate the structure and properties of the interface between uranium metal and hydride using a holistic modelling approach that combines calculations over differing length scales. In order to enhance the safety of the spent fuel during storage by defining the structural details of the metal-hydride interface and its relationship with the mechanical stress and reactivity at the interface. We aim to provide (1) an atomistic model of the early stages of formation of the hydride on the metal, (2) the percolation of hydrogen through the oxide layer formed due to metal corrosion by oxygen, and (3) the defect chemistry at the metal-hydride and metal-oxide interface.