[rapnie]

Well, if all this R&D investment gives us clean energy for the next centuries at affordable cost, it is an improvement right? And we don't have to cover our land and waters with solar farms that have their own externalities (limited lifetime, waste, harmful materials, etc).

[raffraffraff]

The problem is surviving long enough to make a fusion breakthrough. Fusion may actually be an impossible engineering problen. Fission is cheap and easy by comparison.