Heat is much less valuable then electricity. Then again, a nuclear plant is a great heater! Only about 33% of heat generated by a reactor is converted to electricity. So would it be worth it to produce heat instead of power?
There are 3412 Btus per kWh of electricity. So 1 MMBtu = 293 kWh. One kWh wholesale electricity sells for say 3-6 cents. So that's about $8.80-17.60 per MMBtu of electricity sold.
In contrast, natural gas for industrial process heat in the U.S. has sold for about $3.50-$5.50 per MMBtu over the past few years (via @EIAGov eia.gov/dnav/ng/ng_pri…) quite a bit lower than value of 1 MMBtu of electricity
A reactor produces 3x as much heat as it does power. So instead of 1 MMBtu of electricity, a reactor could produce 3 MMBtu of heat. That would be worth $10.50-$16.50, quite competitive with the value of electricity that could be generated w/same amount of heat ($8.80-$17.60).
The U.S. has some of the lowest gas prices in the world however. These graphics show (a) global prices of liquefied natural gas imports & U.S. gas export prices and (b) the spread in global LNG prices vs U.S. export prices. 
As the above graphics show, global prices in markets dependent on LNG imports tend to be ~$2-5/MMBtu higher than U.S., e.g. typically in the range of $5.50-$8.50/MMBtu.
That means that a nuclear plant generating heat for industrial processes or district heating/cooling in a place like Japan, China, or Spain, might earn more like $16.50-$22.50 in lieu of generating electricity worth $8.80-$17.60. Now we're talking.
Finally, a nuclear plant used to produce heat is going to be simpler than one used to generate electricity, as you don't need the steam turbine generating plant portion of a typical nuclear plant. That might reduce capital cost of a plant by 15-20% (see world-nuclear.org/information-li…).
There would presumably be ongoing maintenance cost savings as well, from the simpler design. All you need are heat exchangers to extract heat from the reactor.
Finally, depending on the temperature of heat needed, you might be able to design a lower temperature reactor that could be much simpler, safer, and easier to construct than a typical light-water pressurized or boiling water reactor for power generation.
Indeed, China National Nuclear Corporation (CNNC) announced it is working on a simpler "swimming pool" reactor rated at 400 MW of thermal output that would be designed to produce 90 degree C water for district heating. decentralized-energy.com/articles/2017/…
CNNC estimates/claims they can build such a reactor for RMB1.3bn-1.4bn (around $200m). That works out to only $500/kW of thermal output.
For comparison, it historically cost ~$2,000/kW of electric output or $667/kW of thermal output to build reactors in Korea & India according to @J_Lovering @arthurhcyip @TedNordhaus paper (sciencedirect.com/science/articl…) That's probably comparable to Chinese reactor construction costs. 
In sum: the economics of generating heat rather than electricity from #nuclear plants may make a lot of sense where it competes against natural gas, especially imported LNG. Thermal-only reactors may cost less and earn more than reactors for power generation.
If simpler, smaller, and cheaper #nuclear reactors can be designed/commercialized that are passively safe & easier to build, this may be a competitive alternative/supplement to electrification (with low-carbon power sources) as the world works to decarbonize heating.
(And note: I didnt get into the possibility of co-generating heat and power. If you can produce electricity AND use the exhaust heat from the steam generating unit to provide district or process heating, that may work out even better.)
This is also one of the markets they @oklo is thinking about with their tiny nuclear "battery" -- eg process heat (or power) for remote mining, drilling rigs, military bases etc where delivered fuel costs can be even higher than LNG. Did I get that right @jakedewitte?
.@ElephantEating raises the key design / public acceptance issue for district heating with nuclear reactors:
But as noted in my thread, lower temp reactors mean easier to design to be passively safe.
But as noted in my thread, lower temp reactors mean easier to design to be passively safe.
Also: Im currently sitting < 1 km from a low-temp 6 MW thermal reactor @MIT! en.wikipedia.org/wiki/MIT_Nucle… It's passively save & in middle of Cambridge. Here's another in my old home town, Portland, OR reactor.reed.edu There are reactors like this in middle of lots of cities.
I'm told by the guy who knows (Staffan Qvist) that "This is not just future stuff, 72 power (i.e. not isotope/materials/research) reactors supply some form of non-electric product today, 45 district heat, 12 district + process heat, 6 process heat only, 9 desalination."
