Spent fuel is a very different pollutant, one that at worst destroys local ecosystems (global impact with fossil) and the hard to handle stuff exists in quite limited quantities. Yes, it's pretty hard to put it somewhere nobody touches it, but it's not like we don't already need to find a solution to that problem.
I was actually talking about spent fuel rods, the kind you put in concrete casks (and yet they will outlive those). Because that's the stuff that will stay dangerous for time beyond human comprehension.
Radioactive water is not usually a concern. There are heat exchangers between an inner loop with a very small amount of water that is radioactive (but not forever or highly radioactive) and an outer loop with just... seawater. Maybe you're thinking about Fukushima, where they dumped a lot of water on an open core?
You do understand that producing zillions of square km of semiconductor and zillions of metric tons of batteries isn't going to exactly be environmentally benign, right?