High Temperature Zirconium Alloys for Nuclear Fusion and Generation IV Fission Reactors

这项研究将开发未来核聚变和第四代裂变反应堆所需的新型锆基材料，这些材料可以实现无碳能源生产，零或减少长期核废物。这项工作将与卡勒姆聚变能源中心（CCFE）和罗尔斯·罗伊斯公司合作进行，并与曼彻斯特、牛津、帝国理工学院、班戈尔、DECHEMA法兰克福和ANSTO悉尼合作。核能是我们从化石燃料及其大规模二氧化碳排放过渡的能源结构的关键部分。然而，由于对长寿命放射性废物、安全性和成本的担忧，核能受到阻碍。未来先进的核反应堆概念解决了这些问题。核聚变不会产生这种长寿命的放射性废物，而且本质上是安全的，不可能发生失控反应。下一代第四代裂变反应堆提高了效率和容量，显著降低了燃料使用量和成本，同时具有本质安全性。对于聚变和裂变，除了等离子体物理和反应堆工程方面的挑战外，还需要超越现有能力的先进材料。本计划开发的先进材料将在聚变和下一代裂变反应堆所需的高工作温度下保持稳定。1950年至1970年开发的锆合金在目前的裂变反应堆中表现出色，这是由于它们的中子横截面低，耐腐蚀，在中等温度（约330摄氏度）下具有足够的强度。然而，聚变和第四代裂变在更高的温度（500-800摄氏度）下运行，这与它们的先进冷却剂有关：液态金属，氦气或熔盐。目前的Zr合金缺乏高温强度，因此本项目需要开发新的高温Zr合金。在80年代和90年代为高温Ti合金开发的合金设计方法将扩展到Zr，利用它们的共同晶体结构。强度将通过（1）结构细化和（2）用高强度金属间化合物增强来获得。将注意观察用于产生这样的机械性能改进的Si、Al和Cr添加物是否也促进对氧化、腐蚀或辐射损伤的环境恢复力。第二种合金设计策略将采用局部高熵合金（HEA）方法，这是材料科学的一个最近和快速发展的领域。将开展工作以验证基于锆的HEA，从我们最近对ZrTiVNb HEA系统的概念验证研究（https：//doi.org/10.1016/j.actamat.2019.01.006），到ZrTiVTa和ZrTiV（Nb/Ta）X（X = Cr，Si，Al）HEA系统。该项目将帮助英国保持在聚变和第四代裂变研究的前沿，并在快速发展的HEA领域确立英国的地位，目前英国在该领域的代表性不足。

This research will develop new zirconium-based materials needed for future nuclear fusion and generation IV fission reactors, which allow carbon-free energy generation with nil or reduced long-lived nuclear-waste. The work will be carried out in partnership with Culham Centre for Fusion Energy (CCFE) and Rolls-Royce, with collaborations across Manchester, Oxford, Imperial College, Bangor, DECHEMA Frankfurt and ANSTO Sydney.Nuclear power is a key part of the energy mix in our transition away from fossil fuels and their large-scale emission of carbon dioxide. However, nuclear is held back by concerns over long-lived radioactive waste, safety and cost. Future advanced nuclear reactor concepts address these concerns. Nuclear fusion produces no such long-lived radioactive waste and is inherently safe with a runaway reaction impossible. Next Generation IV fission reactors have increased efficiency and capacity for significantly reduced fuel usage and cost whilst being intrinsically safe. For both fusion and fission, in addition to plasma physics and reactor engineering challenges, there is a need for advanced materials that are beyond current capabilities.The advanced materials developed in this programme will be designed for stability at the high operating temperatures required for fusion and next-generation fission reactors. Zirconium alloys developed 1950-70 excel in current fission reactors, owing to their low neutron cross section and corrosion resistance, with adequate strength at moderate temperatures (~330 degrees C). However, fusion and Gen IV fission operate at much higher temperatures (500-800 degrees C) associated with their advanced coolants: liquid metal, helium gas or molten salt. The current Zr alloys lack high temperature strength, necessitating this project's development of new high temperature Zr alloys.Alloy design approaches that were developed for high temperature Ti alloys, through the 80's and 90's, will be extended to Zr, exploiting their common crystal structure. Strength will be gained (1) by structural refinement and (2) by reinforcement with high strength intermetallic compounds. Attention will be made to see whether Si, Al and Cr additions employed to generate such mechanical property improvements also promote environmental resilience against oxidation, corrosion or irradiation damage. A second alloy design strategy will employ the topical high entropy alloy (HEA) approach, which is a recent and rapidly growing field of materials science. Work will be undertaken to characterise zirconium-based HEAs, building from our recent proof of concept study on the ZrTiVNb HEA system (https://doi.org/10.1016/j.actamat.2019.01.006), to ZrTiVTa and ZrTiV(Nb/Ta)X (X = Cr, Si, Al) HEA systems. These have the potential to further increase high temperature mechanical properties and environmental resistance.This project will help to keep the UK at the cutting edge of fusion and Gen IV fission research, as well as establishing the UK's presence in the rapidly developing HEA field, where it is currently underrepresented.