Development of System and Component Life Management Techniques for Optimal Design and Maintenance of Power Plants

电厂的性能是设计、运行环境和维护的函数。今天，对严格的安全和高效率的需求正在推动发电厂的极限，特别是核电厂，其结果是维护成本大幅增加。由于标准的变化，新建电厂或现有电厂继续运行的决策笼罩着不确定性。此外，现有的核电站正进入其寿命的最后25%，老化的影响变得越来越显著，而且难以预测。这需要更高水平的检查或更换，从而影响工厂的性能，其中许多检查或更换结果是无效或不必要的。因此，迫切需要提高预测植物衰老影响的能力和诊断衰老的能力。国际上对植物老化现象进行了重要的研究，主要集中在了解物质和化学与环境的关系。这项重要的研究有助于更好地理解失效机制和预测失效机制的能力。然而，老化对电厂性能还有其他影响，例如对冷却流量或传热的影响，这些影响会影响安全边际。因此，在某些情况下，实际故障条件不一定是组件或系统的寿命限制因素。另一方面，设计中使用的许多模型在分析工厂安全性时仍然非常保守。最终的结果是，由于大量的不确定性，不可能真正优化整个工厂的性能。这项研究计划的主要目标是开发用于设计和操作维护的寿命管理技术，以提高工厂的整体可靠性。为了实现这一长期目标，有必要研究以下领域：(1)改进检测工厂系统和组件老化条件的方法，以及(2)在模拟老化系统/组件上进行实验，以确定对热工液压和安全裕度的影响。这项工作将允许开发结合植物设计、植物条件和老化影响的预测模型。为了检测老化状况，我们的研究小组已经有了诊断系统，如超声波断层扫描、电容断层扫描、中子射线照相和热成像。这些技术将应用于组件和环境的各种组合，以开发改进的检测方法。这项工作将与图像处理方法相结合，以改进定量分析，因为这是目前检查程序的一个弱点。这个实验项目将纳入表征衰老效应的方法。我们已经开发了三种技术来改变表面条件来模拟机械老化/冲击损伤，使用可变形塑料来模拟表面变形，以及用于模拟生物污垢效果的生物化合物。实验将测量老化条件对冷却剂流动、三维流动扰动和压降的影响。热水力学模型作为老化条件的函数将被开发。将为一组选定的系统和组件开发生命管理模型。与OPG的联系将能够提供有关工厂某些部分状况的一些数据。这项工作的新颖之处在于，它将涉及多个学科，包括机械和其他应力，与材料和化学的相互作用，以及热工行为。

Power Plant performance is a function of design, operational environment, and maintenance. Today, the demand for rigorous safety and high efficiency is pushing the envelope of power plants, particularly nuclear plants with the result of significant increases in cost of maintenance. Decision making for new power plants or continued operation of existing power plants is shrouded with uncertainty due to changes in standards. In addition, the existing plants are entering the last 25% of their life and ageing effects are becoming significant and difficult to predict. This affects plant performance by requiring a higher level of inspections, or replacements, many of which turn out to be either ineffective or unnecessary. Hence, there is a strong need for an improved ability to predict effects of plant ageing and the ability to diagnose ageing. Significant research is conducted international on plant ageing phenomena concentrating mostly on understanding material and chemistry relationships with the environment. This important research leads to a better understanding of failure mechanisms and the ability to predict failure mechanisms. However, there are other impacts of ageing on the plant performance, such as impact on cooling flow or heat transfer which affects safety margins. Thus in some cases, the actual failure condition is not necessarily the life limiting factor for the component or system. On the other hand, many of the models used in design remain significantly conservative for analyzing plant safety. The end result is that it is not truly possible to optimize the overall plant performance due to the large amounts of uncertainty.The key objective of this research program is to develop life management techniques to be used both in design and in operations and maintenance to increase the overall reliability of the plant. To achieve this long term objective, it is necessary to study the following areas: (1) Improved methods for detecting ageing conditions in plant systems and components, and (2) Perform experiments on simulated aged systems/components to determine impact on thermalhydraulics and safety margins. This work will then allow development of predictive models that combine knowledge of plant design, plant condition, and ageing effects. For the detection of ageing conditions, our research group already has diagnostic systems such as ultrasonic tomography, capacitance tomography, neutron radiography, and thermography. These techniques will be applied to various combinations of components and environments to develop improved inspection methods. The work will be combined with image processing methods for improved quantitative analysis as this is currently a weakness in the inspection program.The experimental program will incorporate methods for representing ageing effects. We have developed three techniques to change the surface conditions to simulate mechanical ageing/impact damage, surface deformation using a deformable plastic, and a biological compound for simulating the effects of biofouling. The experiments will measure the impact of the aged condition on coolant flow, three dimensional flow disturbance, and pressure drop. Models for thermalhydraulics as a function of the ageing condition will be developed.Life management models will be developed for a select set of systems and components. Contacts with OPG will be able to provide some data regarding the conditions of some portions of the plant.The novelty of this work is that it will involve multiple disciplines involving mechanical and other stresses, interaction with materials and chemistry, and thermalhydraulic behaviour.