Prediction of Flow-Accelerated Corrosion Caused by Swirling Flow in Continuous Piping Elements

Abstract

Flow-Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in nuclear power plants as a high priority. In one of the pipe rupture accidents caused by FAC in the past, it was reported that the swirling flow generated in continuous piping elements affected FAC behavior at the downstream of the orifice in power plants, but the parameters determining the FAC-related swirl intensity remained unclear. To add the effect of swirling flow to FAC and Liquid Droplet Impingement Erosion (LDI) Prediction Software for Pipe Wall Thinning (FALSET), which was developed by authors, the dominant swirl intensity parameters must be elucidated. In this study, a FAC prediction model downstream of the orifice due to the swirling flow generated in continuous piping elements was developed by numerical simulation. From the results, the geometric factor expressing the intensity of FAC increases with swirl intensity. Finally, the FAC prediction model was constructed by applying the relationship between the dominant swirl intensity parameters and the geometric factor.