You’ve got some amount of water in the “dirty loop” exposed to the fissile material, and in the spent fuel storage tanks. Contaminated water is stuck for that use, but that isn’t “spending” the water. The water stays contained in those systems. They don’t magically delete water volume and need to be refilled. Outside of that you have your clean loop, which is bog standard “use heat to make steam, steam move turbine, moving turbine make electiricity, steam cools back to water”. Again, there’s no part of that which somehow makes the water not exist, or not be usable for other purposes.