Vaporizing nuclear fuel is how we enrich it. Uranium => Uranium Hexaflouride sublimed at 57C => Gaseous centrifuge to separate the isotope. We've been doing it since the Manhattan Project, since before nuclear power plants were even a thing.
https://en.wikipedia.org/wiki/Enriched_uranium#Centrifuge_te...
Implying that nuclear lightbulbs for terrestrial generation would have been in this elite group of winning technologies is just ludicrous.