[Robotbeat]

All of those things are harder than a nuclear thermal rocket. Got to walk before you run. And a fusion reactor is actually likely to be much heavier than a fission one (at least in the near term).

They're using Low Enriched Uranium for this design. We have plenty of uranium (resources are huge, but no one bothers to prove them into reserves until the price is right), and not much is required for this project.

Don't be disappointed by the first step in a journey not taking you immediately to the destination.