Abstract
This study is aimed directly to the containment system of the Lungmen nuclear power station, which is an advanced boiling water reactor, constructed and operated by the Taipower company. A two-phase, multi-component, air-water-steam flowing model simulating different dynamic phenomena of containment system, during design basis accidents, is established. Importances and characteristics of this study are to establish an independent fluid thermohydraulic computer code, which is based on the fundamental theories, for the containment system of the Lungmen nuclear power station. It can analyze the thermodynamic properties and parameters of fluids in the containment during accidents or transients. Then we can provide the time-varying system response data as the boundary conditions for the detail analysis of hydrodynamic loading inside wetwell. Based on fluid dynamics and heat transfer processes, the model can be divided into several submodels, which includes drywell, water clearing, air clearing and wetwell. The mass and energy conservation of thermodynamics can be used to analyze the drywell and wetwell submodels. By adding the momentum equation to water clearing and air clearing submodels, the clearing velocity and parameters of flowing fluids can be calculated. In this investigation, two LOCAs of desian basis accidents are the targets to be analyzed and compared. One is the Feedwater line LBLOCA, and the other is the Main-Steam line LBLOCA. By analyzing two LBLOCAs, we can understand different effects created by these two DBAs. The thermodynamic porperties in the drywell or in the wetwell can compare with PSAR results of the Lungmen nuclear power station, to assure that the established computer program is correct and precious. Then the data of fluids flowing in the vents can act as the boundary conditions, which includes velocity of water clearing and mass of the fluid flowing, to enable the calculations of hydrodynamic loading on the structures submerged or above the suppression pool.