Modeling the impact of disruption induced heat loads on ITER plasma-facing components*

In ITER, transient heat loads during the current quench (CQ) phase of unmitigated disruptions are expected to impact strongly some regions of the actively cooled beryllium first wall (FW) and tungsten (W) divertor plasma-facing components (PFC). The very strong thermionic emission of W at melting temperature, or the halo currents entering the FW provide the driving (J X B ) force for melt motion. Additionally, relativistic runaway electrons (RE) carrying currents of up to 10 MA and kinetic energy up to 20 MJ could be formed during the CQ phase. The power width of this runaway beam is extremely small (~mm) and may thus induce extremely high volumetric heat loads on PFCs in very localized areas. This paper presents analysis of the CQ and RE-induced heat loads and the subsequent melt dynamics using the DINA-SMITER-GEANT4-MEMOS-U workflow developed at the ITER Organization. Emphasis is on scoping simulations to examine the thresholds for CQ heat flux and RE volumetric heat deposition before disruption mitigation will be mandatory to ensure PFC integrity and lifetime consistent with the ITER Research Plan.