[dongobongo]

This is just the dumb/old kind of nuclear in which the reactors are operated at really high power which means they have to be actively cooled so that the fuel doesn't melt itself and cause release of radiation. The reason they run at really high power, is because they think it's cheaper to get more power out of the same reactor. But of course they have to build a bunch of emergency systems, themselves expensive, to make sure the reactor is actively cooled - and these inevitably fail at some point.

The alternative, pursued most prominently by new companies like (usnc.com) is to operate at much lower power density which means the reactor does not have to be cooled to prevent it from melting. It can just dissipate the small amount of heat without any active measures or expensive equipment. Making the economics work is the trick.