[koe123]

For such an approach I’ve always thought it seemed a risk to launch something like that into the air. E.g. what happens if the rocket explodes while taking off? Or something bad happens when in space? Will it rain nuclear material?

[fragmede]

Obviously you just put the nuclear material inside of the in-flight data recorder so it will survive a rocket failure.

If you're being serious, Cassini had those kinds of questions with its launch about its RTG but that didn't have enough nuclear material for it to be a problem.

If we were to try and use a fusion reaction in space, we'd probably use the existing one.