Comprehensive 3-D simulation and performance of ITER plasma facing and nearby components during transient events—Serious design issues

Abstract

A key obstacle to a successful magnetic fusion energy production in Tokamak reactors is performance during abnormal events. Abnormal events include plasma disruptions, edge-localized modes (ELMs), vertical displacement events, and runaway electrons. While tremendous efforts are being made to find ways to mitigate such events, a credible reactor design must be able to tolerate a few of these transient events. We have recently enhanced our comprehensive HEIGHTS (High Energy Interaction with General Heterogeneous Target Systems) simulation package to enable detailed 3-D investigation of the overall aspects of plasma-material interaction processes during all the transient events. Advanced models and numerical tools were developed to efficiently couple major key processes during the transient events, and in particular disruptions and giant ELMs. These include dynamic interaction, deposition, and scattering of the escaping core plasma particles with the evolving and propagating secondary divertor vapor/plasma in the strong magnetic field. These details are critical for assessing the damage to all interior components, including the hidden structure and the first wall which were not directly exposed to these transient events and never thought to be affected as a result. Despite developing numerous efficient numerical techniques and solution methods, such calculations take several months on current supercomputers to complete. Our present results show, for the first time, that unmitigated transient events could cause significant melting and vaporization damage to most interior and hidden components, including the first wall that were not directly exposed to these events. The current ITER divertor design may not work properly and need to be significantly modified or redesigned to prevent this damage.