Assessment and improvement of resilience of NPP through advanced modelling and simulation

这个合作研究项目与坎杜能源公司。包括五个研究主题，包括a）材料水平的长期性能，B）钢筋混凝土（RC）壳单元的非弹性行为，c）集成最先进的分析工具来模拟结构系统，d）使用模拟工具评估核电厂系统的地震恢复力，以及e）结果可视化。为了了解钢筋混凝土结构的长期徐变和收缩行为，将在实验室中对表面积与体积比类似于典型核电厂安全壳结构的样本进行测试。湿度和温度边界条件将根据典型安全壳结构的内部环境进行定义。试验结果将被用来开发一个更准确的徐变和收缩模型，通过该模型可以预测安全壳建筑物的长期变形和收缩过程。在结构单元级，将基于修正的压缩场理论（MCFT）开发具有减少的积分点数量的壳单元。数值单元将能够预测的刚度和破坏过程的RC元件，包括裂纹的发展和扩展下的静态和动态负载。 在系统一级，新开发的元素将与多伦多大学开发的其他复杂的数值模拟工具相结合。集成的数值模型将允许在超设计水平地震和随后的潜在内部压力增加的情况下对大型核电厂系统进行建模和模拟。将进行一系列分析，以建立一个结构反应数据库，并将开发一个软件工具，使结果可视化。反应数据库和可视化工具将用于在地震事件发生后立即为决策者提供支持。考虑到安大略超过50%的电能依赖于核电，对核电厂弹性的准确理解将导致一个可持续和弹性的社会。

This collaborative research project with Candu Energy, Inc. includes five research topics which encompass a) long-term performance at the material level, b) inelastic behaviour of a reinforced concrete (RC) shell element, c) integration of state-of-art analysis tools to simulate a structural system, d) to assess seismic resilience of NPP system using the simulation tool and e) visualization of results. To understand the long-term creep and shrinkage behaviour of reinforced concrete structures, a specimen with surface-to-volume ratio similar to a typical NPP containment structure will be tested in the laboratory. The humidity and temperature boundary condition will be defined based on the internal environment of a typical containment structure. The experimental results will be used to develop a more accurate creep and shrinkage model through which the long-term dehumidification and shrinkage process of a containment building can be predicted. In the structural element level, a shell element with a reduced number of integration points will be developed based on modified compression field theory (MCFT). The numerical element will be able to predict the stiffness and failure process of an RC element including crack development and propagation under both static and dynamic loads. At the system level, the newly developed element will be integrated with other sophisticated numerical modelling tools that have been developed in University of Toronto. The integrated numerical model will allow modelling and simulation of a large nuclear power plant system under beyond-design level earthquakes and subsequent potential internal pressure increases. A series of analyses will be carried out to build a database of the structural responses, and a software tool will be developed to visualize the results. The response database and visualization tool will be used to support decision makers immediately after an earthquake event. Considering more than 50% of electric energy in Ontario relies on nuclear power, the accurate understanding on the resilience of NPPs will lead to a sustainable and resilient society.