Henning wrote: That x-ray transparent fluid (helium gas, I don’t know at which pressure it gets fluid
It doesn’t, not even at the multi-megapascal pressures that were researched for certain other fission and fusion reactors. “Fluid” in this usage is a generic term the same as “working fluid”… the He will still be gaseous
I think those extreme He pressures required for other, more widely known applications were why Lerner-hakase specifically pointed out that in an FF the He pressure would only be a few bar.
