"And preferably with the waste heat being put to productive use"
How about extracting CO2 from the atmosphere. It doesn't have to be cost efficient if it's part of the cooling design.
The biggest pain in the ass about nuclear is turning it up and turning it down. Not only does it take hours and days, it can't be at peak efficiency both ways. If your reaction is optimized for a certain heat, rate, fuel consumption; whatever; and you 'turn that down'; something is getting more radioactive absorbing those neutrons, and you're making radioactive waste. The best reactor is the one that can operate for 20 years without touching it. Unless something goes wrong, in which case it can still be turned down, and then off.
What if the whole power of the reactor went towards atmospheric CO2 extraction? I would say convert it to gasoline and industrial oxygen (by using local water), but anything made out of carbon and oxygen is on the table. There is as little waste heat as possible here, as it is stored in the output that is trucked away. You will never make money on this scheme, rather; your intermediate waste products are valuable items that society will happily absorb, and they'll even tip you for it. That's a good place for a nuclear plant operator to be, but the real money, obviously, is in selling electricity to utilities.
Now, if you want some heat for your electric generator turbines, you simply turn down that CO2 process, and leave the reactor alone, and you've got excess heat.
Seems like an easy sell to me.