[stu2b50]

It’s a sliding scale in the end. You can have a fusion system that barely breaks even, or only slightly breaks even, and then is still more expensive than traditional energy sources after factoring in fixed costs and maintenance.

[NoMoreNicksLeft]

Even then, are there no sales possible? I'd think that a borderline fusion reactor would be commercially viable if only for research. You could probably sell a dozen of those around the world. But unless something really weird's going on with the physics, a borderline system is just the mark 1, and everyone expects mark 2 to be more efficient.

[pfdietz]

For example, a DT fusion reactor based on ITER would be two orders of magnitude larger (in volume and mass) than a fission reactor of the same power output. It might "work" in some technical sense, but be completely economically impractical.