The effect of vanadium and copper on defect structure generation during neutron irradiation of zirconium-based materials

在现代核反应堆中，锆合金被用来包裹核燃料。使用锆合金是因为它们对中子非常透明，在水冷反应堆中具有良好的腐蚀性能，并且具有合理的机械强度。为了使核燃料组件在反应堆中的使用时间比现在更长，锆合金不断得到进一步的发展。事实上，决定从核燃料中提取多少能量的是包裹着的锆合金的性能，而不是浓缩水平。改进所谓的“燃耗”将减少反应堆关闭次数，增加单位核废料发电量。核反应堆堆芯是对结构材料要求最高的环境之一。当被插入反应堆时，包裹核燃料的锆合金会受到腐蚀、氢气吸收和严重的辐射损害。辐照像锆一样的金属会导致非常戏剧性的微观结构变化，因此性能也会发生变化。因此，非常详细地了解辐照过程中的微结构演变是非常必要的。辐照损伤演化对材料的辐照硬化、辐照尺寸变化等性能也有非常重要的影响。后者对本项目特别重要，因为尺寸变化受合金化学成分的影响很大。到目前为止，对合金化学、辐照过程中缺陷结构的发展和辐照引起的尺寸不稳定性之间的关系仍然缺乏明确的认识，这是试图开发新的锆合金时的一个特别问题。目的：PHD项目将专注于两种开发合金，一种是V合金，另一种是铜添加合金，它们在Bor-60研究反应堆中进行了辐照。-基于X射线衍射的线型分析将被用来获得两种合金在五个不同的注量水平下的位错线密度。-此外，详细的电子显微镜分析将使用高分辨率的EDX图谱来探索环路排列和铜和钒的作用。这些发现将与正在进行的对在相同辐照活动期间受到辐照的更传统的锆合金的分析进行比较。-告知辐照损伤演变的模型。这名学生的研究成果将提供给“MIDAS”，这是一项由曼彻斯特牵头的900万GB EPSRC项目拨款(EP/S01702X/1)，合作伙伴包括牛津大学、帝国理工学院和库勒姆聚变能源中心，以及一系列英国和国际研究和工业利益相关者。学术新颖性：对新合金添加对辐射诱导缺陷形成及其演化的影响的新见解。到目前为止，还没有在中子辐照后对这些材料进行详细的研究。这项工作将建立在正在进行的将新的表征技术应用于现有商业合金的工作的基础上。

In modern nuclear reactors, zirconium alloys are used for encapsulating nuclear fuel. Zirconium alloys are used because they are very transparent to neutrons, have excellent corrosion properties in a water-cooled reactor and have reasonable mechanical strength. Zirconium alloys are constantly developed further in order to utilise nuclear fuel assemblies in a reactor for longer than what is achieved today. In fact, it is the performance of the encapsulating zirconium alloys that determines how much energy can be extracted from nuclear fuel and not the enrichment level. An improvement of the so-called 'burn-up' will result in fewer reactor shut-downs and more power generation per unit of nuclear waste.Nuclear reactor cores are one of the most demanding environment for structural materials. When inserted into a reactor, zirconium alloys undergo corrosion, hydrogen pick up and significant levels of irradiation damage as they encapsulate nuclear fuel. Irradiating a metal like zirconium results in very dramatic microstructural changes and therefore alterations of the performance. Hence, very detailed understanding of the microstructural evolution during irradiation is highly desirable. The irradiation-induced damage evolution also has very important consequences for the material properties such as irradiation hardening and irradiation-induced dimensional changes. The latter is of particular interest for this project as the dimensional changes are greatly affected by alloy chemistries. To date, a clear understanding of the relationship between alloy chemistry, development of defect structure during irradiation and irradiation-induced dimensional instabilities is still missing, which is a particular issue when trying to develop new Zr-alloys. Aims:The PhD project will focus on two development alloys, one with V and one with Cu additions, which were irradiated in the BOR-60 research reactor. - X-ray diffraction-based line profile analysis will be utilised to obtain dislocation line densities for both alloys irradiated to five different fluence levels. - In addition, detailed electron microscopy analysis will explore loop arrangements and the role of Cu and V using high resolution EDX mapping. The findings will be compared with ongoing analyses of more conventional Zr-alloys irradiated during the same irradiation campaign.- Inform modelling of irradiation damage evolution. The student's work will feed into 'MIDAS', a £9M EPSRC programme grant (EP/S01702X/1) led by Manchester, with partners at Oxford, Imperial and Culham Centre for Fusion Energy, alongside a range of UK and international research and industrial stakeholders. Academic Novelty:New insight into the impact of novel alloy additions to irradiation induced defects that form and their evolution. To date no detailed study of these materials have been performed following neutron irradiation. The work will build on the ongoing working applying new characterization techniques to existing commercial alloy.