Flow accelerated corrosion in piping components under single and two phase flow conditions

流动加速腐蚀（FAC）是老化电厂特别是核电站面临的严重的安全可靠性问题。这种现象会导致大面积的管道磨损，从而导致突然和灾难性的失效。造成FAC的机制有两种：(i)一种电化学现象，它取决于工作流体的化学性质；（ii）由于工作流体和金属表面的相对运动而对金属的侵蚀。提出的项目的目的是研究流动加速腐蚀（FAC）在管道组件。特别是，在一系列流动条件下，将评估两个背靠背90度弯头中单相流和两相流对FAC的水动力影响。之所以选择这种结构，是因为通过对大多数电厂管道系统的在线监测，已经确定弯头是最容易发生FAC的。实验将进行不同的背靠背的弯头分离距离和弯头安排的进口流速和两相流形式的范围。弯头的流动和磨损率都将被表征，以引出导致FAC的主要流动机制。该项目将与加拿大原子能有限公司（AECL）合作执行。该研究项目的结果将提供信息，通过确定最容易发生FAC的流动条件和管道配置，可用于更好地管理对核电厂FAC的在线监测。双方设想，该项目将成为一个更全面的研究计划的开始，以更好地了解核电厂中的FAC，从而提高核电站的安全性、可靠性和经济性。

Flow Accelerated Corrosion (FAC) is a serious safety and reliability problem facing aging power generation plants, especially nuclear power plants. This phenomenon results in the wear of large areas of piping that can lead to sudden and catastrophic failure. There are two mechanisms responsible for FAC: (i) an electrochemical phenomenon which depends on the chemical properties of the working fluid, and (ii) erosion of metal due to the relative motion of the working fluid and the metal surface. The objective of the proposed project is to investigate flow accelerated corrosion (FAC) in piping components. In particular, the hydrodynamic effects of single and two phase flow on FAC in two 90-degree elbows arranged back-to-back will be evaluated under a range of flow conditions. This configuration was chosen because elbows have been identified as most prone to FAC through on-line monitoring of piping systems in most power plants. Experiments will be performed for different back-to-back elbow separation distances and elbow arrangements for a range of inlet flow velocities and two-phase flow regimes. Both the flow and wear rates in the elbows will be characterized to elicit the principal flow mechanisms responsible for FAC. The project will be performed in collaboration with Atomic Energy of Canada Limited (AECL). The results from this research project will provide information that can be used for better management of on-line monitoring of nulcear power plants for FAC by identifying the flow conditions and piping configurations that are most prone to FAC. It is envisaged by both partners that this project will be the start of a more comprehensive reserach program to better understand FAC in NPP that will lead to enhanced safety, reliability and economics of nuclear power plants.