Two dimensional LOCA (loss-of-coolant accident) analysis for fusion reactors

Two dimensional loss-of-coolant accident (LOCA) analysis has been made for the inboard shield of a US design proposed for the International Thermonuclear Experimental Reactor (ITER). The finite element heat transfer code TOPAZ2D has been used to model the inboard shield. It is assumed that the plasma continues to operate for 10 seconds after the onset of LOCA. During this time the heat source consists of the heat flux on the first wall (FW) tiles, the nuclear heating, and the radioactive decay heat. After the 10 seconds, the decay heat becomes the only heat source. The magnets are assumed intact during and after the accident and heat is radiated from the shield to the magnet's thermal shield which is at 70{degree}K. The temperature response of the shield has been calculated up to 12.8 hours after the LOCA starts. The results show that the temperature everywhere in the shield is tolerable. The maximum temperature of the back of the shield, which is made of lead, reaches 41{degree}C at the end of the 10 seconds plasma-on period. The maximum temperature of the first wall reaches 520{degree}C at 7.5 hour from shutdown. After that it starts to decrease slowly. 8 refs., 5 figs.