The fast discharge system of ITER superconducting magnets

High DC current interruption system and large energy dissipation system are required for the protection of ITER superconductive coils. The ITER superconducting magnets will store up to 56 GJ of magnetic energy per operation cycle. In case of coil quench and other fault conditions the energy stored in the coils must be discharged quickly and safely within a discharge time constant from 7.5 to 14 second. It can be achieved by Fast Discharge Unit (FDU), which consists of DC circuit breaker and energy dump resistors. The paper will present its peculiarities and challenging issues and the design and simulation results of FDU system.