Comment by pfdietz

Definite solution? It's a definite non-solution, even if the plasma physics is more nailed down. The ARC reactor (fully scaled up SPARC with tritium breeding blanket) would have a power density 40x worse than a PWR primary reactor vessel, and supplying the world's primary energy demand with them would require 100x more beryllium than the USGS estimated resource (not reserve) of that element.