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

流动加速腐蚀(FAC)是老化电厂尤其是核电站面临的一个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，从而导致突然的灾难性故障。FAC有两种机制：(I)取决于工作液的化学性质的电化学现象；(Ii)由于工作液和金属表面的相对运动而对金属的侵蚀。拟议项目的目标是研究管道部件中的流动加速腐蚀(FAC)。特别是，将在一定的流动条件下评估单相流和两相流对背靠背排列的两个90度弯头内FAC的水动力影响。之所以选择这种配置，是因为通过对大多数发电厂的管道系统进行在线监测，发现弯头最容易产生FAC。在一定的进口流速和两相流流型范围内，对不同的背靠背弯头间距和弯头布置方式进行了实验研究。弯头中的流动和磨损率都将被表征，以得出导致FAC的主要流动机制。该项目将与加拿大原子能有限公司(AECL)合作实施。这一研究项目的结果将通过确定最容易发生FAC的流动状况和管道配置，为更好地管理FAC的Numcear发电厂的在线监测提供信息。双方预计，该项目将是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.