Development and applicability analyses of ADS-4 entrainment model in large advanced PWR

Two new models of liquid entrainment through a vertical tee branch are proposed based on theoretical analyses and experimental data, which can well predict the test results of the prototype facility of CAP1400 and the scaled down facility of AP1000. Moreover, in order to verify the applicability of the new entrainment models, these models are implemented to RELAP5 through the safety analyses with a 2 in. cold leg SBLOCA in AP1000 comparing with the original RELAP5. The contrastive results show that the RELAP5 with proposed entrainment models has more reasonable results. In addition, the modified RELAP5 can calculate less primary coolant inventory which is more conservative. Besides, the less coolant inventory is accord with the beyond design basis accident test of APEX facility (Advanced Plant Experiment). Therefore, the proposed entrainment models are more appropriate for the ADS-4 entrainment safety analyses in large advanced PWR.