Investigating the Effects of Piping Configuration and Water Supply Pressure on Air Intrusion

A study to understand the effects of geometry and water supply pressure on the void transport has been performed using RELAP5. Two different piping configurations were considered for a hypothetical nuclear power plant. The cases that were analyzed considered switchover between two different water supplies, ie water storage tank and SX for a safety system that acted as the ultimate heat sink. Results were interpreted based on the differences in the geometries of the piping configurations and supply water pressures. The void that was transported to the pump intake had larger values for the configuration with longer voided section and shorter traveling distance (model A) compared to the model with shorter voided section and longer traveling distance (model B). The main reasons for this were Model A had more air than model B and the traveling distance of the void, and therefore, the transport time was longer in model B letting the air to compress more during this duration until it reached the pump intake.