Zeroing in on a reactor with the "Right Stuff"
for making the right kinds of steam.
(Most of below from several different Wikipedia URLs.)

Coal boilers make much more sophisticated types of steam than a nuclear boiler's crude "Teakettle" steam.

In addition to the basic saturated steam made by both nuclear and coal boilers, coal boilers also make "superheated" steam and "reheated" steam.  This is what gives coal burning power plants their greater thermal efficiency.

(Below)  The Pressurized Water Reactor or PWR.  2/3 of the world's conventional water cooled reactors are of this type.

(Below)  The Boiling Water Reactor or BWR.  1/3 of the world's conventional water cooled reactors are of this type. 
Lacks one level of containment.

"Teakettle" or basic saturated steam [evaporator steam] is the only kind of steam produced by conventional nuclear reactors running at about 550°F (300°C).  This produces a pressure of about 1,050 pounds per square inch.  Saturated steam contains droplets of water that will erode the blades of the turbine, so the steam is run through a "dryer" - a series of baffles - that cause the water droplets to separate and drain down to the bottom of the dryer and then be returned to the feedwater inlet system.  The dried steam is then sent into first an intermediate pressure turbine and then a low pressure condensing turbine.  As you can see from the efficiency curve (below), running at these temperatures produce only mediocre efficiencies, but if this is all the hotter the reactor can go, its what's accepted.

(Below) The core of a typical fossil fuel power station.  Note the steam lines going back and forth between turbine and boiler.
Note the by-pass (10) on the high pressure turbine stage (11).

Coal, natural gas, and oil burning fossil fuel boilers begin with the firebox jacket [evaporator] (1) making a hotter 670°F (300°C) saturated steam which produces about 2,500 psi, but since a fossil fuel fire boiler can easily heat twice that temperature, the wet saturated steam is taken off ABOVE the water at the TOP of the "steam drum" (device 17, above) and then (2) run through the boiler again and superheated an additional 350°F or so.  Since the steam is at 2,500 pounds per square inch (its basic saturated pressure) but 350 degrees hotter than needed to make the basic pressure, it becomes very dry and has the characteristics of a gas rather than a fog-like vapor.  This very hot and dry steam is used to drive the high pressure stage of the three-stage turbine.  Notice from the efficiency chart these temperature conditions may produce a 5% more efficient power plant.

Going into the high pressure turbine stage (11) [note the bypass valve, 10] at 2,500 psi and 1,000°F, the steam expands, transferring its energy into mechanical energy, loosing both pressure and temperature in the process, and may come out at 500 psi and 500°F.  Steam saturation temperature at 500 psi is 467°F, so the steam coming out is almost fog-like with droplets - potentially very damaging to turbine blades if the temperature were any lower.  No problem with a fossil fuel boiler - just (3) reheat it back to 1,000°F [but still at 500psi] with yet another pass through the boiler before sending it, still at 500 psi, into the intermediate (9) and condensing (6) turbine stages.  Nice and dry so fog-like water droplets won't damage the turbine blades and buckets, this adds a fair slug of thermal energy too, pushing efficiency even higher.

You may want to trace out the steam path in the fossil fuel power plant drawing above, paying attention to the evaporator steam drum (device 17).  Devices 11, 9, and 6 are the high, intermediate, and low pressure turbines.  Boiler tubes 19 are the superheat, boiler tubes 21 are the reheat.

Conventional reactors just don't cut it when it comes to competing with coal's heat. 
This is why you don't hear anyone talking about converting coal burning power plants to conventional nuclear.

All is not lost.  There are advanced reactors that, in the author's opinion, could be set up to emulate coal boilers.

1. The General Electric-Hitachi PRISM  On the NRC Docket.                 (Considered a modern version the Integral Fast Reactor.)
2. The Russian BN-800, which resembles the                                   (A commercial product with a strong history.  Built and sold by Russia.)
3. United States' Experimental Breeder Reactor II (EBRII) built at Idaho National Laboratories.  A fast-neutron device, this type of reactor is passively safe through heat sensitivity, using thermal expansion beyond normal operating temperature to impair neutron flow.  In a test of the EBR-II, during a full power run, its heat exchanger's cooling water was turned off, causing the reactor to go over temperature.  By not allowing the normal shutdown systems to interfere, the reactor power dropped to near zero within about 300 seconds (5 minutes). No damage to the fuel or the reactor resulted.  Radial core expansion and control rod drive elongation provided the overall negative reactivity feedbacks to lower the reactor power during the unprotected loss of secondary cooling event.  Additional minor reactivity effects are fuel Doppler Broadening feedback, primary coolant density feedback, and fuel thermal expansion.

The EBRII was later slightly modified and then operated as the Integral Fast Reactor (or IFR) prototype. As the IFR prototype, it achieved first criticality in 1965 and ran for 30 years. 

President Bill Clinton killed the construction of the extremely promising IFR reactor in 1994 as payback to the antinuclear environmentalists by defunding the project.  http://www.senate.gov/legislative/LIS/roll_call_lists/roll_call_vote_cfm.cfm?congress=103&session=2&vote=00175 

   http://en.wikipedia.org/wiki/Experimental_Breeder_Reactor_II          http://en.wikipedia.org/wiki/Integral_Fast_Reactor 

4. The never-built Liquid Fluoride Thorium Reactor (LFTR).            http://en.wikipedia.org/wiki/Molten_salt_reactor