Simulation of transient thermohydraulic characteristics under blowdown conditions of a SBLOCA on middle-pressure loop

The simulation was performed on a middle-pressure thermohydraulic loop. A uniformly AC heated stainless steel tube was used as the test section. Break area was designed in the blow-down section. The experimental parameters were as follows that the pressure is 0.7-2.2MPa, the initial inlet subcooling is 50-120°C, the mass flow rate is 1750-2800 kg/m²·s and the heat flux is 0.3-1 MW/m². From the experiment, the relationships of loop pressure, mass flow rate and wall temperature versus blowdown time are derived, and the curves reflecting the mutual influences among pressure, mass flow rate, initial inlet subcooling and critical time are also obtained.