The next big problem after hitting positive energy production will be sustainability. My understanding is that the walls of the reactor get hit with enough stra

The next big problem after hitting positive energy production will be sustainability. My understanding is that the walls of the reactor get hit with enough stray neutrons that they degrade (often in radioactive ways). Unlike in fission reactors where you can put in a lot of absorptive shielding (like lead), in a fusion reactor you have to keep the magnets close to what they are working on. Note, I am not talking about really long term radioactive waste here, more like things that are dangerous for less than 100 years. Still problematic, but not for millions of years like fission.