Atomic-Scale Characterisation of Reactor Pressure Steels

反应堆压力容器是核裂变反应堆的安全关键部件。因此，RPV钢的长期稳定性、强韧性对发电行业至关重要。将使用的主要实验技术将是原子探针层析成像。这种尖端的显微技术能够对钢的微观结构进行三维、逐个原子的表征，从而提供了对溶质聚集和由此导致的脆化的基本机制的独特见解。其他实验工作将包括电子显微镜和机械性能测量。这项研究对于预测现有裂变工厂的安全运行寿命，以及在英国设计和制造新的反应堆，如小型模块反应堆，都是至关重要的。这一项目将使牛津大学和劳斯莱斯公司之间的持续合作成为可能。目前的老化实验(接近5年的连续热处理)将继续进行，从熔炉中取出，并以适当的间隔测试/检查老化的样品。目前的机制理解是，任何纳米级的析出都更有可能出现在位错或晶界上。因此，将更加重视晶界行为，特别是磷以及镍/锰/铜等元素的偏析。这将需要更多地使用原子探头以外的仪器，如聚焦离子束(FIB)来产生特定位置的样品，以及透射菊池衍射(TKD)来表征晶界的晶体取向错误。该项目也是继续与UCSB的奥德特小组合作的机会。这种合作使我们能够获得中子辐照的样品，以补充我们的热老化样品的分析。这使得以前有机会利用爱达荷州国家实验室的设施对活性物质进行表征。然而，它现在提供了利用库勒姆聚变能源中心(CCFE)材料研究实验室的专业知识和能力的可能性。3D化学分辨原子成像的能力对于解锁微结构-性能关系具有令人兴奋的影响，这些关系对于设计新材料、开发工艺路线、了解在役性能和恶劣环境中的退化/失效机制至关重要。这项对第四代小型模块化反应堆结构材料的研究，也将有助于反应堆钢的安全关键监测。因此，该项目与EPSRC的多个主题直接相关，如物理科学、制造未来、工程和能源，研究领域包括：核裂变(维护)、能源应用材料(生长)、材料工程-金属和合金(维护)。它属于EPSRC关于一个多产和有弹性的国家的主题，为英国核研究的复兴做出了贡献。

The reactor pressure vessel (RPV) is a safety critical component of a nuclear fission reactor. Hence, the long-term stability, strength and toughness of RPV steels are of vital importance for the power-generating industry. The main experimental technique to be used will be atom probe tomography. This cutting edge microscopy technique enables a three-dimensional, atom-by-atom characterisation of the microstructure of the steel, providing unique insight into the fundamental mechanisms of solute clustering and the resulting embrittlement. Additional experimental work will involve electron microscopy and mechanical property measurements. This research is critical both for the predicting the safe operating lifetimes of existing fission plants, and also in the design and manufacture of new reactors, such as Small Modular Reactors, in the UK.This is project will enable ongoing collaboration between Oxford and Rolls Royce. The current ageing experiments (approaching 5 years of continuous thermal treatments) will be continued with removal from furnaces and testing/examination of aged samples at suitable intervals. Current mechanistic understanding is that any nano-scale precipitation will be more likely found either on dislocations or grain boundaries. Because of this more emphasis will be placed on grain boundary behaviour and in particular the segregation of elements such as phosphorus, as well as Ni/Mn/Cu. This will require greater use of instruments other than atom probe, such as Focused Ion Beam (FIB) to generate site specific specimen, and Transmission Kikuchi Diffraction (TKD) to characterise the crystallographic misorientation of the grain boundaries.The project also represents an opportunity to continue to collaborate with the Odette Group at UCSB. This collaboration has enabled access to neutron irradiated samples for complementary analysis to our thermally aged counterparts. This has previously led to opportunities to use the facilities at Idaho National Laboratory for the characterisation of active materials. However, it now presents the possibility to exploit the expertise and capabilities at the Culham Centre for Fusion Energy (CCFE) Materials Research Laboratory.The capability for 3D chemically-resolved atomic imaging has exciting implications for unlocking microstructure-property relationships critical to design of new materials, developing processing routes, understanding in-service performance and degradation/failure mechanisms in harsh environments. This research into structural materials for GenIV Small Modular Reactors, will also contribute to safety critical monitoring of reactor steels. As such, this project is directly relevant to multiple EPSRC themes such as Physical Sciences, Manufacturing the Future, Engineering and Energy, across research areas: Nuclear Fission (Maintain), Materials for Energy Applications (Grow), Materials Engineering-Metals and Alloys (Maintain). It falls under the EPSRC themes of a Productive and Resilient Nation, contributing to the renaissance of nuclear research in the UK.