80% of the fusion energy from DT fusion comes out in fast neutrons, which ignore magnetic fields.
The other 20% has to come out somewhere. If it could be converted to electrical energy maybe it could avoid surfaces (Helion plans to do this, with DD + D3He) but when it's just 20% of the output that doesn't buy you much.
And DT fusion neutrons are even worse than fission neutrons, since they are much more energetic (and because only 3% of the energy in a fission reactor is released in neutrons.) The 14 MeV DT neutrons are above the threshold for (n,p) and (n,alpha) reactions, which cause gas to accumulate in reactor materials. The helium produced by (n,alpha) reactions accumulates in tiny bubbles that would reach extreme pressures and rip materials apart.
Well, no, not completely solving it. There are limits to neutron fluence materials will withstand. Even neutron heating can't be too nonuniform in the blanket.
The other 20% has to come out somewhere. If it could be converted to electrical energy maybe it could avoid surfaces (Helion plans to do this, with DD + D3He) but when it's just 20% of the output that doesn't buy you much.