Safety characteristics of options for plasma-facing components for ITER and beyond

Plasma-facing components (PFC) likely dominate the safety hazards of the International Thermonuclear Experimental Reactor (ITER) and post-ITER machines. To gain regulatory approval and for fusion energy to fulfill its ultimate attractive safety and environmental potential, safety must be considered when selecting among PFC options. Current PFC safety information is summarized. PFC safety issues fall into seven areas: disruption tolerance, disruption severity, tritium inventory and permeation, accidental energy release, activation/toxin hazards, cooling disturbances, and system issues. PFC options include current ITER mainline options (Be or W coating, C tiles), variants on current ITER options, and liquid metal divertors. No PFC option that the authors have examined is free of critical safety concerns. There are also innovative ideas that may improve any PFC´s performance: superpermeable vacuum ducts, helium self-pumping, and gaseous divertors. Recommendations and a future strategy are presented