Thermal Hydraulic Performance Analysis Of Passive Containment Cooling System Of AP1000

The design of a nuclear reactor containment building is of key importance in order to enhance the safety of a nuclear power plant.Owing to nuclear accidents such as TMI,Chernobyl and Fukushima,more and more attention is paid to the passive concept in nuclear power development.In order to improve the safety of new generation nuclear power plant,passive systems are widely used,passive containment cooling system in AP1000 is one of the typical example of such kinds of systems.It's function is to transfer the heat produced in the containment to the atmosphere and keep the pressure in the vessel below the threshold under such accidents as Loss of coolant(LOCA),main steam line break(MSLB),etc.A proper model simulating the system behavior is needed for system design and safety analysis,and a multivolume lumped parameter approach is employed in order to analyze the containment integrity and to study the long term response of postulated Loss of coolant(LOCA)accidents and Main steam line break(MSLB)accidents.However,the temperature and pressure distributions cannot be described detailed by such model,which is important to study the T-H characteristics in the containment.In this research,using Matlab software,the PCCS model is established based on lumped parameter method.Comparing with the results calculated by WGOTHIC,it shows that the point model is reliable.Then filter the input parameters,the air temperature,wind speed and the discharge data of the break are selected as research targets.The results based on different combinations of input parameter are calculated and analyzed.By analyzing the calculations,it shows that under LOCA,the air temperature and wind speed will influent the time of peak pressure's occurrence.The lower the temperature is,the later peak pressure occurs.Furthermore,API 000 containment was modeled in ANSYS FLUENT focusing on the Falling Film Evaporation(FFE)phenomenon and the effect in decay heat removal during design basis accidents(DBA's)was studied.For this,Eulerian Wall Film model in ANSYS FLUENT is applied to study the aforementioned phenomenon.The mass transfer between the liquid film and the gas mixture of vapor in the outside airflow path of the PCCS is analyzed and shows promising performance.