작동유체에 따른 주증기관 파단사고 해석에 관한 연구

Abstract

In a nuclear power plant, the main steamline break is one of the major accidents along with other accidents of the plant such as the loss-of-coolant accident and the steam generator multi tube rupture event. The main steamline break accident occurs when there is a rupture in the main steamline which is connected to the steam generator. When this occurs, the steam generator is exposed to huge pressure and temperature differences (almost 70bar to atmosphere pressure). As a result, a variety of wave forms and abnormal phenomenon (choking, cavitation) unfold. The usage of an appropriate compressible fluid model is vital to predict the main steamline break numerically in order to arrive at accurate results. For this purpose, in this study, different working fluids (Ideal Gas model, Redlich Kwong Model, Peng Robinson Model, IAPWS Model – taken as a standard model for comparison), different turbulence intensities (1%, 5%, 10%) and different mass flow rates (1A , 2A, 3A, 4A) are used to analyze a steamline break in the steam generator. Also, the velocity and density fluctuations of the fluid are calculated at two points for different cases with respect to time. The results show that different mass flow rates and turbulence intensities have no effects on the velocity fluctuations of the fluid within the allowable range of use. The results also show that, the Redlich Kwong Model and the Peng Robinson Model matches closely to the standard of the IAPWS model when compared to the Ideal Gas model.