The reason we don't have fusion is that we keep looking for above break-even (and for proper fusion power plant we need ratios way above 10:1, afaik) in aneutronic fusion.
If we accepted neutron radiation in the process, which is what would lead to radioactive fusion chamber cladding you mention, we could have broken even already - the experiment JET reactor had the design capacity to run at above 1:1, but wasn't equipped for the damage from neutron radiation.
Breaking even in fusion puts you where fission was in 1942. And that's just a step. The engineering obstacles to practical fusion are enormous, far greater than those facing any advanced fission reactor scheme. I very seriously doubt fusion will ever be practical.
If we accepted neutron radiation in the process, which is what would lead to radioactive fusion chamber cladding you mention, we could have broken even already - the experiment JET reactor had the design capacity to run at above 1:1, but wasn't equipped for the damage from neutron radiation.