Experimental and numerical studies on heat transfer and fluid flow characteristics in a vacuum vessel of fusion reactor after the loss-of-vacuum-events occurred

As one of thermofluid safety studies in ITER (International Thermonuclear Experimental Reactor), heat transfer and fluid flow characteristics of buoyancy-driven exchange flows through breaches in a vacuum vessel (W) of fusion reactor were investigated quantitatively by using a preliminary loss-of-vacuum-event (LOVA) apparatus which simulated the Tokamak VV in ITER with a small-scaled model. In the LOVA experiments, helium gas and air were used as the working fluids and the VV was heated to maximum 200 degrees C. The present study showed that the exchange mass and fluid temperature distributions in the VV under the LOVA conditions depended on the breach positions and breach numbers. Furthermore, the exchange flows through the breaches were analyzed numerically to predict velocity and temperature distributions in the VV, and these predicted results could simulate the experimental results well. 5 refs., 11 figs