Retrofitting Coal Power Plants With Small Nuclear Reactors

Higher steam pressures and temperatures match coal combustion performance.

Nuclear energy is enjoying a resurgence. Some nations are deferring the retirement of reactors and other countries are developing new generation fission designs that are safer and more cost-effective than current technology. By retrofitting existing coal-fired power plants, new small modular reactors, or SMRs, are at the forefront of this development. 

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Episode Transcript:

With a greatly renewed interest in alternate energy sources driven by climate change and war in Europe, nuclear energy is enjoying a resurgence. Germany and Japan are deferring the retirement of reactors, and several nations are developing new generation fission designs that are safer and more cost-effective than current technology.  

Small modular reactors, or SMRs, are at the forefront today, promising simplified engineering, greater safety and lower cost. How low? According to Wall Street analysts Lazard, the levelized cost of electricity from conventional technology new nuclear will be somewhere between $131 and $204 per megawatt hour. By utility scale, solar and wind are significantly cheaper at $26-$50 per megawatt hour.  

Small modular reactors, such as the NuScale units under construction for testing in Idaho, are claimed to have cost between $40 and $65 per megawatt hour, based on NuScale’s 12 module, 924 MW plant design.  

But in all these economic models, the assumption is that nuclear plants are new builds. There may be another way.  

The Jupiter, Florida, based Holtec International has developed a small modular reactor design called the SMR–160, which like many SMRs features a greatly simplified design with passive cooling and intrinsic safety. The difference with Holtec technology is that the firm proposes to add a series of multi-stage compressors directly on top of the reactor pressure vessel to boost the pressure and temperature of the low enthalpy steam delivered by the reactor itself. 

That steam is low in enthalpy by the standards of power generation, but it’s still 700 PSI at 595°F. The additional pressure and temperature delivered by the compressor super heat or add on will deliver steam that can be tailor made to replace coal fired steam generating units at existing power plants.  

Holtec proposes to drop in their boosted reactor units onto existing coal fired power plant sites, allowing the continued use of the existing generator transformer and power delivery infrastructure. This would represent a cost savings compared to new build nuclear plants, but also a significant savings compared to decommissioning and dismantling existing coal-fired plants.  

The small modular reactor option also takes very little space compared to the large areas needed to store thermal coal. And the company proposes to use this extra space for a battery array capable of storing excess reactor heat, as well as energy generated by solar or wind power. 

The advantages of repurposing existing generation plants are obvious, but it’s unclear whether national regulatory authorities will prove to be a multiyear obstacle to deployment of this SMR technology. The boosted steam SMR–160 system does suggest some intriguing possibilities for industrial process heat as well as power generation, suggesting an avenue for further CO2 reduction in industrial use.  

The technology is new, and the company has not announced commercial contracts yet, but the coal-fired power plants already exist, and the combination of the high cost of decommissioning plus the additional regulatory burden of certifying new sites for nuclear plants suggests that this could be a way forward for nuclear in a timeframe of years rather than decades.

Written by

James Anderton

Jim Anderton is the Director of Content for Mr. Anderton was formerly editor of Canadian Metalworking Magazine and has contributed to a wide range of print and on-line publications, including Design Engineering, Canadian Plastics, Service Station and Garage Management, Autovision, and the National Post. He also brings prior industry experience in quality and part design for a Tier One automotive supplier.