We never got to the bottom of this. So, JamesR, who was right – zapkitty or delt0r? Is the amount of radiation 20 minutes after shutdown the same as background?
Furthermore, I feel the need to lay rest to the OP, whose question was not adequately answered. There are breakthroughs necessary before aneutronic fusion is feasible and cost-effective – but I don’t think one of them is the confinement of the plasma. I’m only talking about DPF technology here – fusion power that is based upon confinement (like Tokamaks) may require better confinement.
