Simulation study on the transient operating characteristics of equal height difference passive containment cooling system

The passive containment cooling system is crucial important for marine nuclear power platform. This paper focuses on the transient characteristic of passive containment cooling system with equal height difference natural circulation under two starting strategy. Dynamic simulation model of passive containment cooling system is set up with APROS software. The simulation results indicate that the initial containment pressure, initial non-condensable gas content, and inlet water temperature have important effects on the pressure drop rate and natural circulation flow rate. And obvious differences exist between the empty tube starting mode and the full tube starting mode. Under single-phase natural circulation conditions, the pressure drop rate of the empty tube starting mode is more than 3.1 times that of the full tube starting mode, while under two-phase natural circulation conditions, the pressure drop rate of the empty tube starting mode is more than 1.5 times that of the full tube starting mode, since large fluctuation amplitude of two-phase flow instability caused by condensation induced water hammer in the natural circulation occurs under full tube starting mode.