EFFECTS OF BREACH AREA AND LENGTH TO EXCHANGE FLOW-RATES UNDER THE LOVA CONDITION IN A FUSION

As one of thermofluid safety studies in ITER, buoyancy-driven exchange flow behavior through breaches of the vacuum vessel was investigated quantitatively using a preliminary LOVA (Loss Of VAcuum event) apparat us which simulated the Tokamak vacuum vessel of a fusion reactor with a small-scaled model. Helium gas and air were used as the working flui ds. Experimental parameters were breach position, breach number, breac h length, breach diameter, breach combination and the wall temperature of the VV. The present study showed that the relationship between the exchange rate and time depended on the magnitude of the potential ene rgy from the ground level to the breach position and the wall temperat ure of the vacuum vessel. The exchange rate decreased as the breach le ngth increased and the breach diameter decreased.