I think a nuclear plant in Manhattan would cost far more than just building the plant in outer NY, and then running a big power line in to Manhattan. Sure, the power line would take up space, but so would the nuclear plant's cooling system.
> Sometimes people don't want heating, but you still need to cool down the plant.
You can turn it down or off.
> Remind me why power lines aren't an option?
It's more economical not to waste half the plant's power output. 1 GW of heat comes out the reactor, 50% becomes electricity (with heat pumps you can make that 2x heating) and 50% is low-grade heat sufficient for space heating. You get 1/3 more heating for the same cost.