Advanced structural analysis for the UK nuclear renaissance

核电反应堆包括大型钢制压力容器和高压管道，在使用时必须仔细设计和定期检查，以确保安全。当反应堆运行时，这些系统不仅受到内部压力的影响，而且还受到温度梯度产生的热应力以及在施工过程中被锁定的残余应力的影响。热应力和残余应力通常被称为“二次”应力，它们通常比由直接作用力产生的应力更难测量和预测。通常，这意味着实际上是安全的部件由于二次应力担忧而先发制人地停止使用，除了工厂停机时间外，还会产生巨大的成本。在这个项目中，将开发新的技术来准确地预测部件在使用中受到进一步应力时复杂的多轴二次应力的表现。这将需要开发一个通用的数学框架来描述多轴应力松弛，以及新的计算方法，以便能够分析复杂的现实世界结构。新分析技术的预测准确性将通过一系列使用中子和同步辐射的实验进行测试，以观察金属部件在变化的外部载荷下，内部深处的残余应力是如何变化的。在该项目期间开发的分析技术将与现有的结构完整性评估程序相结合，使其易于在工业中使用，并导致更便宜和更可靠的发电厂。

Nuclear power reactors contain large steel pressure vessels and high-pressure pipework which must be carefully designed and regularly inspected when they are service to guarantee safety. When a reactor is operating, these systems are loaded not just by internal pressure, but also by thermal stresses which arise from temperature gradients, and by residual stresses which are 'locked-in' during construction. Thermal and residual stresses are often termed 'secondary' stresses and they are generally more difficult to measure and predict than the stresses which result from directly applied forces. Often, this means that parts which are in fact safe are pre-emptively taken out of service due to secondary stress concerns, incurring large costs in addition to plant downtime.In this project, new techniques will be developed to accurately predict how complex and multi-axial secondary stresses in components behave as they are further stressed in-service. This will require the development of a generalised mathematical framework to describe multi-axial stress relaxation, along with new computational methods to enable the analysis of complicated real-world structures. The predictive accuracy of the new analysis techniques will be tested in a series of experiments using neutron and synchrotron diffraction to observe how residual stresses deep inside metallic components change as they are subjected to changing external loads. The analysis techniques developed during this project will be integrated with existing structural integrity assessment procedures, allowing them to be readily used in industry, and leading to cheaper and more reliable power plants.