Numerical Analysis and Experimental Verification of Residual Heat Removal Piping System in Power Plants

The Residual Heat Removal (RHR) piping system is one of the most important systems in a nuclear power plant. It is used to provide emergency cooling water to protect the reactor core from high temperature damage during severe accidents. Its strength has therefore to be guaranteed. In order to reduce the accidental risk of power plants, especially owing to strong earthquakes, it is essential to investigate the mechanics behavior of the RHR piping system. This study is divided into two parts. In the first part, both the component test and system test are carried out to investigate the failure modes and mechanics behavior of the RHR piping system. In addition, to confirm the piping system meets the requirements of ASME design code when it is subjected to large earthquakes. In the second part, finite element method is employed for numerical analysis. The numerical models for both the flange joints and the piping system were established and verified according to the experimental results. Furthermore, a simplified model of the flange joints is proposed in this study. By comparing numerical results with the experimental results, it is concluded that all models proposed in this study predict the experimental results reasonably well. In particular, comparing to the original model of the flange joint, the simplified model effectively reduces 70% of the calculation time.