A Study on Wear Locations for HP Turbine Extraction Piping in the Maanshan Nuclear Power Plant

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Nien-Mien Chung
L.C. Wang
Y.P. Ma
Y.M. Ferng

Abstract

Due to the high velocity, relatively low quality and chemical properties of steam, the erosion/corrosion wear are significant in the piping of the BOP (balance of plant) system. A break of the extraction line of the high pressure turbine (HPTB) had occurred in unit #2 of the Maanshan Nuclear Power Plant (NPP). Therefore, the potential wear locations are investigated by the aids of computational fluid dynamics (CFD). In the model, the impingement of liquid droplets on the wall is assumed to be the dominating mechanism to remove wall material. Thus, three-dimensional two-phase flow field is calculated and a wear model is also developed to help determine the potential wear locations. The inlet geometry is modeled to study the upstream effect and the downstream piping layout is also considered. The calculated data are compared to the inspection ones that are reproduced from inspections of pipe wall thickness measured by ultrasonic transmitters (UT) in the Maanshan NPP. The results show the present approach is reasonable and may be a potential tool to identify the regions with higher wear rates.

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