Water Hammer Analysis of an Emergency Cooling System With the Presence of Air

In this paper the effect of air presence in an emergency cooling system of a nuclear power plant during the pipelines pressurization stage is analyzed. The pressure waves propagation along the system pipelines after a fast pressurization of the water tanks is considered. The presence of different amounts of air in one pipe is analyzed. A code was developed to simulate the pressure waves propagation in the system. This code uses the classical Method of Characteristics (MOC) solving the mass and momentum equations. The two phase homogeneous model was used to represent the two-phase mixture in the pipe with presence of air. The maximal pressure in each pipe is calculated for the presence of different amounts of air in one pipe and a time ramp of 0.50 seconds for the operations of valves. The influence of the presence of air in the system is shown.