INVESTIGATION OF subscriptCOOLEDWATER DISCHARGE THROUGH SIMULATED STEAM GENERATOR TUBE CRACKS

The work presented here describes an investigation into the choked flow of initially subscriptcooled water through simulated steam generator tube cracks at pressures up to 7 MPa. The study of such flow is relevant to the prediction of leak flow rates from a nuclear reactor primary side to secondary side through cracks in steam generator tubes. A facility was designed to measure the leak rates and experiments were conducted on choking flow for various vessel pressures and subscriptcooling. Measurements were done on subscriptcooled flashing flow rate through well-defined simulated crack geometries with ratio of channel length to hydraulic diameter between 4.5 and 7. Both homogeneous equilibrium and non-equilibrium mechanistic models were developed to predict two-phase choking flow through slits. Experimental results from data found in literature as well as the data collected in this work are compared with predictions from presented models. It is found that the homogeneous equilibrium model underpredicts choked flow rates of subscriptcooled water through slits and artificial steam generator tube cracks. Additional modeling of thermal non-equilibrium improves the predictability of choking mass flux for the homogeneous model.