Experimental study on flow break by nuclear heating reactor LOCA under shutting down incompletely

The primary circuit of 5 MW nuclear heating reactor and 200 MW nuclear heating reactor are integral natural circulation systems. In cases of loss of coolant accident (LOCA), while the water level reaches the upper edge of the inlet of the heat exchanger, flow break occurs. It has influence on cooling core and stability of the primary circuit. When the reactor can not shut down completely, the influence will be strong. An experiment is described. It is carried out on the thermohydraulic test system HRTL-5 of the nuclear heating reactor. The position of the break is selected on the lower part of the exchanger. The heating section and the riser are geometrically similar. The fluid of the test loop and the steady state condition are same as the reactor's. The system pressure is 1.5 MPa, the heating power under the accident is kept at 20% of steady state power. Results show that a mainly stable drop of the pressure and the heated element temperature is not too high and could not be burnout. But the flow oscillation in the primary coolant circuit occurs when the flow breaks completely at the end, which is unfavorable