That's true, but the problem is that when something goes wrong with a nuclear plant, the consequences can be devastating, and can wipe out all the potential economic advantages.
The problem is that current nuclear power plants are engineering nightmares. Nothing is intrinsically safe, and they depend for their safety on multiple redundant systems. That's not really good design. And you can be sure that bad accidents will continue to happen, caused by the combination of that bad engineering with an economic system that will result in an increasing reduction in oversight as safety in assumed (which is what happened in Japan).
There are nuclear plant designs that are intrinsically safe. That means their safety is ensured by physics, not by engineering. They can't melt down because under those conditions the nuclear reaction itself is quenched. No realistic mechanical failure can result in a release of radiation. But short term economics seems to continue to drive things, with the result that reactors still use 50-year-old technology. Minor improvements in controls and monitoring, but otherwise, pretty much the same old thing. Not good.