TOKES studies of the thermal quench heat load reduction in mitigated ITER disruptions

Disruption mitigation by massive gas injection (MGI) of Ne gas has been simulated using the 3D TOKES code that includes the injectors of the Disruption Mitigation System (DMS) as it will be implemented in ITER. The simulations have been done using a quasi-3D approach, which gives an upper limit for the radiation heat load (notwithstanding possible asymmetries in radial heat flux associated with MHD). The heating of the first wall from the radiation flash has been assessed with respect to injection quantity, the number of injectors, and their location for an H-mode ITER discharge with 280 MJ of thermal energy. Simulations for the maximum quantity of Ne (8 kPa m3) have shown that wall melting can be avoided by using solely the three injectors in the upper ports, whereas shallow melting occurred when the midplane injector had been added. With all four injectors, melting had been avoided for a smaller neon quantity of 250 Pa m3 that provides still a sufficient radiation level for thermal load mitigation.