Experimental investigation on mechanism of high-pressure subcooled water injecting into high-temperature medium under tube rupture accidents

BackgroundDuring the Steam Generator Tube Rupture (SGTR) accident of Lead-cooled Fast Reactors (LFR), liquid metals come into direct contact with water, resulting in a multiphase flow involving liquid metal, water and vapor.PurposeThis study aims to investigate the transient pressure rise and multiphase heat transfer mechanisms resulting from a large quantity of coolant injection into liquid lead-bismuth eutectic (LBE) during the late-phase SGTR accidents.MethodsFirstly, an experimental platform was established to simulate the injection of high-pressure subcooled water into high-temperature LBE, and key experimental variables included injection direction, nozzle diameter, injection pressure, injection time, and thermal oil (simulating LBE) temperature. Then, the interaction phenomena between LBE and water were investigated under controlled conditions, and a prediction model of thermal oil pool temperature change was established on the basis of four thermal physical parameters. Finally, the temperature and pressure changes of two typical thermal oil temperature conditions were compared, and pressure transients and temperature disturbances within the test section were systematically measured and analyzed.ResultsComparsion results show that the pressure impulse and temperature disturbance in the test section are obviously greater when thermal oil had heating effect on subcooled water, with the increase of injection pressure, nozzle diameter and injection time can effectively increase the pressure impulse and temperature disturbance. Under the conditions that the thermal oil temperature is higher than the water saturation temperature, the average error between the model calculation results and the test data is 10.2% while all errors are within ±30%.ConclusionsThe results of this study can provide a theoretical basis for the discovery of heat and mass transfer mechanism and the development of calculation model on the interaction between liquid lead-bismuth eutectic and water.