Effect of local microstructure on cracking of materials for next generation reactors

全球对低碳能源的追求，加上全球能源消费的不断增长，核能与风能和太阳能等可再生能源相结合，为应对这一挑战提供了现实的、可持续的解决方案。加拿大的目标是将自己定位在先进核反应堆设计的前沿，在小型核模块化反应堆（smr）的开发上进行了大量投资。然而，smr距离实施还有10年的时间，必须首先回答一系列紧迫的问题。SMR交付的许多限制来自材料问题：它们将如何响应、老化和在它们将经历的条件下失效。该提案将解决材料性能的关键基础研究问题，这将使SMR安全运行。具体来说，它将研究与smr材料的辐照相关的损伤过程，以及对smr相关金属的断裂，特别是疲劳的后续影响。真正的材料是由颗粒或晶体组成的-每个单独的晶体在其对应力的响应中通常具有高度的各向异性。在许多实际应用中，我们不能忽视这种局部异质性，必须了解不可逆的微观结构变化是如何在局部尺度上发生和传播的。衍射技术能够揭示许多会产生影响的微观结构变化，包括由弹性和塑性晶体各向异性引起的晶间应变，由晶体缺陷（位错）产生的晶内应变，以及变形引起的相变或晶体重定向。本提案的目的是调查监测这些影响的程度，可以为理解疲劳机制和初始裂纹扩展过程提供见解。此外，我们将研究辐照对微结构损伤积累的影响方式。虽然温度和应力是影响材料性能的两个关键变量，但它们并不是唯一的变量。材料在高能辐射环境中（例如在核反应堆或空间中）的行为与在常规应用中不同，因为高能粒子的通量会引入点缺陷和位错，并改变材料的微化学性质。该提案将直接培训HQP的先进技术（包括实验和建模），以及一个广泛的工业（不仅仅是核电）当前和持续感兴趣的研究领域。在现有成功的基础上，它将努力提供一个具有技能和知识的多样化HQP团队，这将对加拿大工业有价值。

The global drive for low-carbon energy sources, combined with a growing worldwide energy consumption, is a challenge to which nuclear energy, in combination with renewables such as wind and solar, provides a realistic, sustainable solution. Canada aims to position itself at the forefront of advanced nuclear reactor designs, with substantial investment in the development of small nuclear modular reactors (SMRs). However, SMRs are still a decade from implementation, and a range of urgent questions must first be answered. Many of the limitations to SMR delivery arise from materials issues: how they will respond, age and fail under the conditions they will experience. This proposal will address key basic research questions into material performance, which will be required to enable safe SMR operation. Specifically, it will investigate the damage processes associated with irradiation in SMR-proposed materials, and the subsequent effect on fracture and especially fatigue of SMR-relevant metals. Real materials are made up of grains or crystallites - each individual crystallite is typically highly anisotropic in its response to stress. In many practical applications we cannot ignore this local heterogeneity and must understand how irreversible microstructural changes occur and propagate at this local scale. Diffraction techniques are able to reveal many of the microstructural changes which will have an influence, including inter-granular strains induced by elastic and plastic crystallographic anisotropy, intra-granular strains generated by crystallographic defects (dislocations), as well as deformation-induced phase transformations or crystallographic reorientation. The aim of this proposal is to investigate the extent to which monitoring these effects can provide insights into understanding the mechanisms of fatigue and the processes of initial crack propagation. In addition, we will investigate the way that irradiation influences microstructural damage accumulation. While temperature and stress provide two key variables that influence material properties, they are not the only ones. Materials behave differently in an energetic radiation environment (e.g., in a nuclear reactor or in space) than in conventional applications due to the flux of high energy particles which introduce point defects and dislocations, and alter the microchemistry of the material. This proposal will train HQP directly in advanced techniques (both experimental and modeling) and in a research area which is of current and ongoing interest to a wide range of industry, not just nuclear power. Building on existing successes, it will strive to deliver a diverse group of HQP with skills and knowledge that will be valuable to Canadian industry.