Modelling advanced fuels for HTGRs at the atomic scale

高温气冷反应堆已被HMG选为先进模块化反应堆演示器的首选技术，并建立在英国在气冷反应堆研究和运营方面的强大历史基础上。这项技术的一个基本特征是涂层颗粒燃料，裂变核包裹在几个交替的碳层和陶瓷层中。到目前为止，运行中的反应堆主要使用UO2燃料内核运行，但要充分实现HTGR的潜力，需要燃料实现至少是当前(全球压水)反应堆船队2-3倍的高燃烧。这可能需要使用先进的燃料，其中碳氧化铀和氮化铀燃料是两个领跑者。为了帮助理解高温气冷堆的最佳燃料，本博士将使用基于静态量子和分子动力学方法的最先进的原子尺度计算方法来：-了解包裹在碳缓冲层中的UO2在照射期间的化学计量比(低燃耗和高燃耗)-考虑先进燃料是否、如何以及为什么是更好的燃料-UCO-UN这将需要预测关键属性，如导热系数如何演变以及体积变化(膨胀)，包括裂变产物的作用，以便为燃料性能代码提供信息。

High temperature gas-cooled reactors have been selected by HMG as the technology of choice for the Advanced Modular Reactor demonstrator and building upon a strong UK history of gas-cooled reactor research and operations. A fundamental feature of this technology is the coated particle fuel, with a fissile kernel encased within several alternating carbon and ceramic layers. Operational reactors to-date have primarily operated with UO2 fuel kernels, but to fully realise the potential of HTGRs requires fuels to achieve high-burns of at least 2-3 times those of the current (global pressurised water) reactor fleet. This may necessitate the use of advanced fuels, with uranium oxycarbide and uranium nitride fuels two front runners. To aid in the understand of optimal fuels for HTGRs this PhD will use state of the art atomic scale computational methods based on static quantum and molecular dynamics methods to:-Understand the stoichiometry of UO2 during irradiation (to both low and high burn-up) when it is encased within a carbon buffer layer-Consider if, how and why advanced fuels are better fuels- UCO- UNThis will require the prediction of how key properties such as thermal conductivity evolve as well as volume changes (swelling), including the role of fission products, in order to inform fuel performance codes.