Heat flux limits on the plasma-facing components for a commercial fusion reactor

In this work, the heat flux limits of conventional plasma-facing components (PFC) were examined. The limits are based on maximum allowable temperature and stress levels in the structures. The substrate materials considered were V, SiC composite and HT-9. The use of Cu also was considered. However, low temperature limits, activation and very limited radiation damage lifetime, make the using of Cu in a commercial power plant unattractive. With selected heat transfer enhancement, the heat flux allowable is about 5.3 MW/m² for lithium-cooled V-alloy, 2.7 MW/m² for helium-cooled SiC composite, and 2.7 MW/m² for helium/water-cooled HT-9. Compared with the maximum heat flux attainable with Cu and cold water (13.4 MW/m²), acceptable power plant materials place severe restrictions on heat removal. The thermal conductivity of SiC composite at 1000°C and after irradiation is a factor of several lowered than the value we used. This indicates a need to examine the heat transfer problems associated with PFC, in terms of material development and enhancement in heat transfer. Physics regimes which can provide low peak and average heat flux should be pursued