CFD Simulation Of Passive Containment Cooling System Test

In order to ensure the integrity of the containment in the case of LOCA loss,the design of passive containment cooling system for nuclear power plants is presented.The system uses the difference between the density of hot and cold fluid to produce natural circulation,take the heat exchange of condensing heat transfer and convective heat transfer,and introduce the waste heat inside the containment shell into the outer tank of the containment shell,so as to realize the effect of cooling and decompression after the accident.Based on the containment and the internal heat exchanger as the research object,in order to study the heat transfer characteristics of the containment cooling system,the heat transfer model of heat exchanger and passive containment was built-in.The CFD program is used to analyze the natural convection of the containment after unstructured meshing.The turbulence model is used to select the standard k-ε turbulence model.The condensing model adopts the wall condensation model,and the high order precision scheme is used to simulate the calculation.The transient term is followed by the second order backward Eulerian scheme.In the case of accident location,the effects of steam injection position,discharge direction and different accident conditions on the pressure,temperature field distribution and gas stratification of the whole passive containment cooling system were studied.The calculation results show that steam of high temperature and high pressure is injected into the containment after the accident,and there is obvious water vapor jet trail at the top of the break;the pressure in the containment along the height direction showed obvious stratification,and the upper layer pressure is small and the lower pressure is larger.With the increase of time,the pressure increased first;with the strengthening of the condensation heat exchanger,then the pressure decreases slowly until the stability;the mass fraction and temperature of the steam reached the maximum at the break point,with the time gradually increased until smooth;the flow rate will gradually decrease with time,and the velocity of the whole part of the containment is smaller.The passive containment cooling system is used to remove the heat from the containment by the natural circulation of the upward movement of the hot vapor and the cold fluid which is condensed by the internal heat exchanger,which is to to achieve the effect of decompression and cooling.In this paper,the CFX program is used to evaluate the thermal hydraulic characteristics of the interior of the containment,which is of reference significance to the design of the passive containment cooling system.