Don’t forget the more than 200 nuclear powered ships currently puttering their way around the world, both above and below the surface. Not to mention the numerous research and testing reactors that don’t product grid energy.

And that doesn’t even get into things like RTGs used on spacecraft and in extremely remote regions where traditional fuels would be nearly impossible to transport reliably. Not technically a reactor in the traditional sense of what people think of as a reactor there, but nuclear energy all the same. The USSR built more than 1,500 of those alone while they were around.

And even ignoring all of those, alternative reactor designs like Thorium molten salt reactors can’t meltdown if cooling systems fail, because the fuel used doesn’t generate heat requiring constant cooling like that.

The only reason most designs we have in use now are uranium based is because that can be used to create weapons, so that’s where the research went… alternatives like Thorium can’t, despite the fuel being much more abundant.