Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
A new advanced safety feature of DVI+(Direct Vessel Injection Plus) for the APR + (Advanced Power Reactor plus), to mitigate and to prevent an ECC(Emergency Core Cooling) bypass phenomena, is presented for an advanced DVI system(DVI+). A protective ECC flow down channel from a high-speed cross flow in a downcomer, a 4-duct which is called an ECC extension duct is installed on the outside of a core barrel. In this study, the feasibility of DVI+ has been tested. They include: (1) 1/5-Scale air-water test, (2) DVI+ duct vibration test, (3) full scale duct injection test. The other design verification tests are also performed. They include: (1) Full scale 3-Fuel assembly cross flow test, (2)1/5-Scale reactor flow distribution test (to be performed, under construction), (3) Core simulator calibration developing test for core flow test. The duct vibration test and the ECC intake fraction tests are performed using full scale DVI duct test facility. The ECC bypass fraction is measured under the condition of the steady- state and direct ECC bypass. The water level of reactor downcomer is controlled at a lower level to prevent the sweep out phenomena from the free surface of collapsed water. A CFD (Computational Fluid Dynamics) analysis was also performed for the simplified scaled model using commercial CFD code. The test results show that the ECC direct bypass fraction is much reduced when the DVI+ duct is applied. The DVI+ ECC extension duct is a good feature to mitigate and to prevent the ECC direct bypass.