A Safety Analysis of the ITER Superconducting Magnet System in Case of Loss of Vacuum in the ITER Cryostat

Abstract

One of the safety analysis for superconducting magnet system in International Thermonuclear Experimental Reactor (ITER) was carried out. The ITER cryostat will hold many superconducting magnets, such as twenty toroidal field coils, a central solenoid coil, and seven poloidal coils. Loss of vacuum of the cryostat was considered as the worst assumption and a safety analysis of the magnets was examined when the assumption would occur. Accordingly, the loss of vacuum will cause the loss of thermal shield vacuum for the magnets and then a large heat transfer will be generated in the cryostat. The magnet pressure and temperature will rise, bringing the magnets to quench. Such behavior was simulated by using a developed computer-aided calculation code. As a result of the calculation, a catastrophic phenomenon doesn`t appear in the assumption. It is observed that a quasi-stable state, where the magnet temperature is kept to less than 7 K, is maintained for more than 600 seconds. Thus, the magnet current can be slowly discharged as in ordinal operation without magnet quench even in such worst assumption due to the large volume of the cryostat. 3 refs., 3 figs., 1 tab.