Abstract
During the start-up and shutdown of Pressurized Water Reactor (PWR), the residual heat removal system is responsible for taking the decay heat out of the reactor core. The heat-up of the residual heat removal system before it is connected to the primary circuit is of great significance for the integrity and reliability of the residual heat removal system and the primary circuit. The mini-flow pipeline in the residual heat removal system is the main component of the system heat-up. Due to its small diameter and fast flow speed, the mini-flow pipeline bear all the pressure head loss under heat-up conditions. In this paper, ANSYS-FLUENT is used to model the mini-flow pipeline, and the resistance characteristics of the pipeline under heat-up condition are analyzed with the change of the flow rate. The results show that FLUENT can accurately predict the pressure drop of the mini-flow pipeline. The results provides the basis for the future optimization. Also, ANSYS is used to analyze the hot and cold fluid mixing between the mini-flow pipeline and the main pipeline and the thermal stress generated. The analysis shows that the stress zones, mainly concentrated in the tee pipe and its upstream, are obvious at the beginning of heat-up and negligible at the end.
