Experimental Study of liquid entrainment in ADS-4 branch tube with double-end inlets of air-water

The vertical tee branch is adopted by the fourth stage Automatic Depressurization System (ADS-4) in AP serials reactors to depressurized the system pressure of reactor vessel during Small Break Loss of Coolant Accident (SBLOCA). Large amount of coolant would be discharged by steam through ADS-4 branch according to the response sequence of Passive Residual Heat Removal System (PRHRS) which may cause the core uncovering. Entrainment experiments with double-end inlets were conducted to analysis the phenomenon of entrainment. The gas flow rate of double-end was different in this study which was more suited to the reactor than existing experiments. The data of onset of liquid entrainment and stable entrainment rate were obtained and compared with other researchers’ experimental results and entrainment models. The discrepancies were found due to the difference of geometric construction of test section and the method of gas inlets.