Investigating atomic-scale mechanisms of thermal ageing in steels harvested from decommissioned pressurisers from Ringhals Units 2 and 4 Reactors

许多国家现在都有雄心勃勃的净零目标。英国是第一个承诺到2050年实现净零排放的国家，这需要大幅增加核能和可再生能源的发电量。核电站的设计寿命为几十年，但在极端条件下，材料降解可能导致核电站提前关闭。在极端反应堆条件下优化材料，以最大限度地减少机械退化，并最大限度地延长工厂寿命，这对于为子孙后代奠定核能可行性的基础至关重要。具体来说，该项目将研究从瑞典Ringhals 2号和4号反应堆退役的稳压器中收集的独特材料的热老化机制。稳压器是压水堆（PWR）一次冷却回路的一个组成部分，它调节一次回路内的压力和温度。因此，这些钢构件的结构完整性对压水堆的长期安全运行至关重要。结合先进的微观结构表征技术，特别是原子探针断层扫描（APT），本研究的主要重点将是这些钢在长达30万小时的长期热老化过程中，原子尺度的微观结构是如何演变的。这种微观结构的变化将与观察到的力学性能的退化直接相关。该项目提供的新的力学见解将对热力学模型的发展至关重要，以了解和预测在更长时间的使用中微观结构和机械性能将如何演变，因此对安全延长压水堆的使用寿命具有重要意义。从这个项目中获得的见解也将有助于为设计更高效的下一代未来反应堆的新材料的开发和选择提供信息。本项目将与我们的工业合作伙伴国家核实验室（英国）和Vattenfall（瑞典）密切合作，它们是欧洲最大的电力生产商之一，也是Ringhals发电厂的所有者/运营商，为本研究提供反应堆前服务组件。该项目直接解决了EPSRC的主题，能源和制造业的未来。它还直接促进了EPSRC优先领域先进材料的一系列主题，例如：材料工程：金属和合金以及能源应用材料。

Many countries now have ambitious net zero targets. The United Kingdom was the first to commit to net-zero by 2050, requiring a significant increase in power production by both nuclear and renewables. Nuclear plants are designed to last many decades but, under extreme conditions, materials degrade potentially resulting in early plant closures. Optimising materials subject to the extreme reactor conditions, so as to minimise mechanical degradation, and maximise plant lifetime, are critical to underpinning the viability of nuclear energy for future generations. Specifically, this project will investigate the mechanisms of thermal ageing in unique materials harvested from the decommissioned pressurisers of the Swedish Ringhals Units 2 and 4 Reactors. The pressuriser is a component of the primary coolant circuit in a pressurised water reactor (PWR) which regulates pressure and temperature within the primary circuit. Hence, the structural integrity of these steel components is of critical importance for the safe long-term operation of PWRs.Using a combination of advanced microstructural characterisation techniques, in particular Atom Probe Tomography (APT), the main focus of this study will be how the atomic scale microstructure in these steels has evolved during long term thermal ageing, up to 300,000 hours in service. This change in fine-scale microstructure will be directly correlated to the observed degradation in mechanical properties. The new mechanistic insights delivered in this project will be critical to the development of thermodynamic models to understand and predict how microstructure and mechanical properties will evolve over even longer times in service and thus is of significant importance to safely extending the operating lifetimes of PWRs. The insights from this project will also help to inform the development and selection of new materials for the design of more efficient next generation future reactors. This project will be undertaken in close collaboration with our industrial partners National Nuclear Laboratory (UK) and Vattenfall (Sweden) who are one of Europe's largest producers of electricity and the owner/operator of the Ringhals power plant supplying the ex-reactor service components to be investigated in this study. The project directly addresses the EPSRC themes, Energy and Manufacturing the Future. It also directly contributes to a range of topics in the EPSRC priority area Advanced Materials, such as: Materials Engineering: Metals and Alloys and Materials for Energy Applications.