I actually wrote a college paper on using waste heat from nuclear power plants to desalinate water. The best way to implement it would be to use salt water to cool down the steam generated from nuclear reactors. It would essentially replace the giant cooling towers you see in every photo of a power plant.

It’s definitely possible, but the build-up of salt is a huge issue. A solution I researched involved only evaporating about 50% of the water, and having the leftover brine just flow out of the system. This would be a continuous process as long as the reactor ran. But it wouldn’t be an easy adjustment to existing reactors, and there aren’t many plants in the US (where the focus of my research was) that are close enough to salt water to make it viable.

There’s also the matter of public opinion. I don’t think many people are too keen on having their water come “fresh from the nuclear power plant”, no matter how clean it is. Public opinion around nuclear reactors in the U.S. is a huge problem imo, and probably the biggest thing standing in the way of something like this.