Yes! Nuclear reactor needs enriched fuel and produces heat. You connect water and it will turn it to steam that you can pipe to do what you want. Usually you want to use it in turbines for electricity production, but you can also use it for desalination, or in oil refinery.
If you don't supply water to the operational reactor, it overheats, and you know what that means... Just kidding, no explosions (yet), it just gets damaged and you loose all loaded fuel.