Using Computational Fluid Dynamics Models to Gain Insight into Separator Degradation Phenomenon

Abstract

During the 17th planned outage of Wolsong Unit 3, Steam Generator #1 was examined to confirm tube integrity following the discovery of a small piece of metal on the tube sheet. Further investigation showed that local erosion was found on the primary separators.

An operational experience (OPEX) review combined with Wolsong station observations showed patterns that suggested detailed analysis might be able to shed light on the degradation mechanism being observed. To facilitate this analysis, a Computational Fluid Dynamics (CFD) model was developed of the separators in ANSYS CFX in order to simulate the conditions under which they had operated. This led to insights regarding operating conditions the separators experience and the associated degradation mechanism that can result. Overall, the approach showed that parametric investigation using CFD is a viable tool for understanding the response of components within complex geometries and operating conditions.

This paper will look at the observed degradation seen in the separators, and discuss the approach taken to model the conditions with the ANSYS CFX code. Consideration of the use of such models to investigate previously unexplained phenomena is explored. Some insights into the phenomenon observed at Wolsong Unit 3 are discussed.