Generation Network Community

The Generation Network covers biomass, coal, gas/oil, hydro, natural gas, or nuclear power generation. The Clean Power Professionals special interest group covers solar, wind and tidal power. 

53,754 Subscribers

Article Post

Is Small Really Big?

Image: A close look of the inner structure of a multi-purpose small modular nuclear reactor models.


Small is the new big when it comes to nuclear power, or is it just another episode in the decades-long continuing drama that nuclear power has been in the United States?  We’re just at the beginning of this newest act, and it’s too soon to tell what the ending will be, but considering all the hype surrounding it, it’s certainly worth taking a closer look.

While there are some 50 designs or concepts in various stages of development or planning around the world, NuScale Power is the driving force today.  In January, 2017, NuScale submitted a design proposal for its modular nuclear power plant to the Nuclear Regulatory Commission, the first such application for a small modular reactor (SMR).  In what must be record-breaking speed, the NRC accepted the design certification application just two months later.  That wasn’t a mere fluke.  NuScale submitted twelve-thousand pages of technical information and spent $30 million in testing the design.  Now, the NRC will take 40 months to review the application and, NuScale hopes, issue its certification.

But breakneck speed is a relative concept when it comes to nuclear energy.  Assuming the NRC grants certification some time in 2020, NuScale will build its first 12-module plant on the site of the Idaho National Laboratory; it will be owned by Utah Associated Municipal Power Systems and operated by Energy Northwest, an experienced nuclear power operator.  The target commercial operation date is 2026.

SMRs such as those NuScale has developed certainly have unique advantages.  First and foremost, they’re small.  Each NuScale module generates 50 megawatts and is 76 feet tall and 15 feet in diameter; it sits on a plant covering just 32 acres, or 0.05 square miles, tiny compared to traditional nuclear plants which typically require 1.3 square miles for 1,000 megawatts.  And, of course, NuScale’s units are modular, so plants can be configured to address medium-term capacity estimates and expanded should the need arise.  They can be much more easily sited, which means they are, at least theoretically, ideal for augmenting renewable installations, such as wind and solar.  An important operating advantage is that refueling a NuScale module would not require shutting down the plant. 

A NuScale module is safer than a traditional nuclear plant, according to NuScale, because of its small size and the large surface area-to-volume ratio of its reactor core, which sits below ground; if a complete power blackout occurred, it would be cooled indefinitely by natural processes, basically gravity powered water, without the need for power, pumps or additional water cooling.  This could successfully address the public safety concerns that have made nuclear plants anathema to so much of the population.  Because of their smaller size and their passive safety design, NuScale argues that the number of people needed to operate its plants would be far fewer than that needed for traditional nuclear plants.  That would bring down operating costs.  But while they require fewer people to operate them, and require much less fuel than large plants, a certain security threat remains, and it’s an open question how the NRC will address the issue, potentially requiring additional personnel, which would add to operating costs.

The big issue remains that of total costs and how they compare with alternatives.  NuScale estimates that it can construct its 12-module plant in Idaho for about $3 billion.  That’s considerably less than what it would cost today to construct a traditional nuclear plant (the most recently constructed, the 1,150 MW reactor at Watts Bar in Tennessee, cost about $4.7 billion), but it still far exceeds the cost of building a natural-gas powered plant.  The cost per kilowatt for a 50 MW module comes to about $5,100, according to NuScale; that compares to a bit less than $1,000 for a combined cycle natural gas fueled power station.  Mass production could theoretically offset some of the loss of economies of scale enjoyed by large plants, but a big boom in orders for SMRs is simply not in the forecast for the foreseeable future. 

But that points to a timely issue.  Distributed and renewable systems are becoming much more economical; in this environment, it might not make sense to opt for a technologically complex and still costly system, especially at a time when demand is slowing or even shrinking.  As for renewable backup, the recent advances in battery technology could, at least in some circumstances, completely obviate the need for back-up generation capacity.

That’s not to say that SMRs aren’t practical and even advantageous in certain circumstances.  Their small size and relatively cheaper construction costs could make them useful for installations where large nuclear plants or even gas-fired plants are not practical for any of a number of reasons.  SMRs could be used to desalinate seawater, refine oil, and load-follow wind and solar, for instance. 

There’s no doubt that SMRs represent a significant advance in nuclear generation, but it’s far too soon to tell whether they will finally move nuclear to a place where it can meaningfully compete in the marketplace with natural gas and renewables as the go-to technology to replace old plants and supply the power needed over the coming decades.


I agree with Richard that SMR commercialization requires significant wait-and-see. Just because you can do something technically, doesn't mean you can justify the business case. SMR still has the waste and security issues of traditional nuclear. Too, the inverted economics are a bit foggy. Siting for a 50MW SMR plant may be incrementally easier than a 1GW traditional plant, but then you need twenty SMR plants to get to 1GW. Also, if it's incrementally cheaper to operate a 50MW SMR than a 1GW traditional plant (fewer staff), is it cheaper to operate twenty SMRs?

Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.

The small LWRs are more economical to operate and are more efficient as that is the characteristics of SMR LWRs over the larger installations. Past a certain size the LWRs and even the BWRs become more inefficient in how they burn the nuclear fuel. It will take the 4th gen MSRs to surpass the cost and efficiencies of the traditional 3rd gen reactors.

I can't understand why the water cooled reactors could come up with a better chemical solution to enhance cooling. But the HTGRs use helium for their coolants and operating medium.

The only reason MSRs are not currently employed is the US DOE research of them was dropped 3 decades ago and the NRC regulations are not really applicable to these 4th gen reactors. In fact due to the 2 last major reactor accidents the NRC became too Draconian with the regulations toward 4th gen reactors.


Plain text

  • No HTML tags allowed.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Lines and paragraphs break automatically.