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SMR cost estimates, and costs of SMRs under construction

Nuclear Monitor Issue: 
Jim Green ‒ Nuclear Monitor editor

Costs of SMRs under construction

Estimated construction costs for Russia's floating nuclear power plant (with two 35-MW ice-breaker-type reactors) have increased more than four-fold and now equate to over US$10 billion / gigawatt (GW) (US$740 million / 70 MW).1 A 2016 OECD Nuclear Energy Agency report said that electricity produced by the plant is expected to cost about US$200/MWh, with the high cost due to large staffing requirements, high fuel costs, and resources required to maintain the barge and coastal infrastructure.2

Little credible information is available on the cost of China's demonstration 2x250 MW high-temperature gas-cooled reactor (HTGR). If the demonstration reactor is completed and successfully operated, China reportedly plans to upscale the design to 655 MW (three modules feeding one turbine, total 655 MW) and to build these reactors in pairs with a total capacity of about 1,200 MW (so much for the small-is-beautiful SMR rhetoric). According to the World Nuclear Association, China's Institute of Nuclear and New Energy Technology at Tsinghua University expects the cost of a 655 MWe HTGR to be 15-20% more than the cost of a conventional 600 MWe PWR.3

A 2016 report said that the estimated construction cost of China's demonstration HTGR is about US$5,000/kW ‒ about twice the initial cost estimates.4 Cost increases have arisen from higher material and component costs, increases in labor costs, and increased costs associated with project delays.4 The World Nuclear Association states that the cost of the demonstration HTGR is US$6,000/kW.5

The CAREM (Central Argentina de Elementos Modulares) SMR under construction in Argentina illustrates the gap between SMR rhetoric and reality. Argentina's Undersecretary of Nuclear Energy, Julián Gadano, said in 2016 that the world market for SMRs is in the tens of billions of dollars and that Argentina could capture 20% of the market with its CAREM technology.6 But cost estimates have ballooned:

  • In 2004, when the CAREM reactor was in the planning stage, Argentina's Bariloche Atomic Center estimated an overnight cost of US$1 billion / GW for an integrated 300-MW plant (while acknowledging that to achieve such a cost would be a "very difficult task").7
  • When construction began in 2014, the estimated cost was US$17.8 billion / GW (US$446 million for a 25-MW reactor).8
  • By April 2017, the cost estimate had increased to US$21.9 billion / GW (US$700 million with the capacity uprated from 25 MW to 32 MW).9

The CAREM project is years behind schedule and costs will likely increase further. In 2014, first fuel loading was expected in 20178 but completion is now anticipated in November 2021.10

Credible assessments of SMR economics

International Energy Agency (IEA) and the OECD Nuclear Energy Agency (NEA): A 2015 report by the IEA and the OECD NEA predicts that electricity costs from SMRs will typically be 50−100% higher than for current large reactors, although it holds out some hope that large volume production of SMRs could help reduce costs − if that large volume production is comprised of "a sufficiently large number of identical SMR designs ... built and replicated in factory assembly workshops."11

The agencies were even more underwhelmed by Generation IV concepts: "In terms of generation costs, generation IV technologies aim to be at least as competitive as generation III technologies ... though the additional complexity of these designs, the need to develop a specific supply chain for these reactors and the development of the associated fuel cycles will make this a challenging task."11

European Commission: The European Commission released its 'Communication on a Nuclear Illustrative Programme' (PINC) in 201612, along with a Staff Working Document which informs the main report.13 The Staff Working Document noted that the nuclear industry has been considering the deployment of commercial SMRs since the 1950s, but little has come of it and only a few SMRs are under construction around the world. The Document notes that the cost of investment per kW is likely to be higher for SMRs compared to larger reactors. It notes that claims supporting SMR economics ‒ which emphasize standardization, learning effects, cost sharing and modularization ‒ "are difficult to quantify due to the lack of existing examples". The Staff Working Document further states: "Due to the loss of economies of scale, the decommissioning and waste management unit costs of SMR will probably be higher than those of a large reactor (some analyses state that between two and three times higher)."

Atkins Report: A report by the consultancy firm Atkins for the UK Department for Business, Energy and Industrial Strategy found that electricity from the first SMR in the UK would be 30% more expensive than power from large reactors, because of reduced economies of scale and the costs of deploying first-of-a-kind technology.14

The Atkins report said there is "a great deal of uncertainty with regards to the economics" of the smaller reactors. The report estimates that the levelized cost of electricity for an SMR based on a pressurized water reactor design would be £86‒124/MWh with a central estimate of £101/MWh, and adds this caveat: "However it is recognised that SMR is a new technology and there is a substantial risk that these costs will be higher than this if costs accumulate during development or if financing costs are initially higher than they are for large nuclear."14

South Australian Nuclear Fuel Cycle Royal Commission: The Royal Commission was stridently pro-nuclear but was nevertheless unimpressed by the economic case for nuclear power in South Australia.15 In its May 2016 Final Report, the Commission stated: "Taking into account the South Australian energy market characteristics and the cost of building and operating a range of nuclear power plants, the Commission has found it would not be commercially viable to develop a nuclear power plant in South Australia beyond 2030 under current market rules."

The Royal Commission identified hurdles and uncertainties facing development and commercial deployment of SMRs including the following:15

  • SMRs have a relatively small electrical output, yet some costs including staffing may not decrease in proportion to the decreased output.
  • SMRs have lower thermal efficiency than large reactors, which generally translates to higher fuel consumption and spent fuel volumes over the life of a reactor.
  • SMR-specific safety analyses need to be undertaken to demonstrate their robustness, for example during seismic events.
  • It is claimed that much of the SMR plant can be fabricated in a factory environment and transported to site for construction. However, it would be expensive to set up this facility and it would require multiple customers to commit to purchasing SMR plants to justify the investment.
  • Reduced safety exclusion zones for small reactors have yet to be confirmed by regulators.
  • Timescales and costs associated with the licensing process are still to be established.
  • SMR designers need to raise the necessary funds to complete the development before a commercial trial of the developing designs can take place.
  • Customers who are willing to take on first-of-a-kind technology risks must be secured.

A report by WSP / Parsons Brinckerhoff, commissioned by the Royal Commission, estimated levelized costs of electricity of A$225/MWh (US$161/MWh) based on the NuScale SMR design (and slightly lower costs based on the abandoned mPower design).16 That's 2.5 times higher than the implausible figures being promoted by NuScale Power: the company's "target" for its first project is US$65/MWh.17 Costs per MWh for NuScale are estimated by WSP / Parsons Brinckerhoff to be 22% higher than large PWRs (A$184 or US$132).

WSP / Parsons Brinckerhoff concluded:16

"Analysis of the economic viability measures for the scenarios under consideration suggests that nuclear power plants in South Australia are not likely to be economically viable, unless:

  • capital and operating costs of nuclear power plants are reduced to or below the lowest extreme of the plausible range of costs considered by this study; and/or
  • the cost of capital (debt and equity) is reduced to a level that is unlikely to be commercially available from the open market; and
  • electricity prices increase dramatically as a result of strong climate action, such as 100% reduction in emissions relative to 2000 levels by 2040 to 2050."

Mark Cooper: A September 2014 journal article by Dr Mark Cooper, senior research fellow for economic analysis at the Institute for Energy and the Environment at Vermont Law School, assesses the prospects for SMR technology from three perspectives:18

  • the implications of the history of cost escalation in nuclear reactor construction for learning, economies of scale and other process that SMR advocates claim will lower cost;
  • the challenges SMR technology faces in terms of high costs resulting from lost economies of scale, long lead time needed to develop a new design, the size of the task to create assembly lines for modular reactors and intense concern about safety;
  • and the cost and other characteristics – e.g. scalability, speed to market, flexibility, etc. – of available alternatives compared SMR technology.

Cooper concluded that the recent (in 2014) decisions of major vendors Westinghouse and B&W to dramatically reduce SMR development efforts "reflects the severe disadvantages that SMR technology faces in the next several decades. … Westinghouse and B&W are big names in the nuclear space, had thrown a great deal of weight and money into advancing SMRs as the next big thing and the savior of the nuclear industry, but they failed."18

In a separate 2014 paper, Cooper argues that the economic potential of SMRs is weak for the following reasons:19

"First, the viability of SMRs is dependent on the very economic processes that have eluded the industry in the past. The ability of the small modular reactor technology to reverse the cost trajectory of the industry is subject to considerable doubt. … SMR technology will need massive subsidies in the early stages to get off the ground and take a significant amount of time to achieve the modest economic goal set for it.

"Second, even if these economic processes work as hoped, nuclear power will still be more costly than many alternatives. Over the past two decades wind and solar have been experiencing the cost reducing processes of innovation, learning and economies of scale that nuclear advocate hoped would benefit the "Renaissance" technology and claim will affect the small modular technology. Nuclear cost curves are so far behind the other technologies that they will never catch up, even if the small modular technology performs as hoped.

"Third, the extreme relaxation of safety margins and other changes in safety oversight is likely to receive a very skeptical response from policymakers.

"Fourth, the type of massive effort that would be necessary to drive nuclear costs down over the next couple of decades would be an extremely large bet on a highly risky technology that would foreclose alternatives that are much more attractive at present. Even if the technology could be deployed at scale at the currently projected costs, without undermining safety, it would be an unnecessarily expensive solution to the problem that would waste a great deal of time and resources, given past experience.

"Finally, giving nuclear power a central role in climate change policy would not only drain away resources from the more promising alternatives, it would undermine the effort to create the physical and institutional infrastructure needed to support the emerging electricity systems based on renewables, distributed generation and intensive system and demand management."

Energy and Power Engineering: A 2014 study published in Energy and Power Engineering concluded that fuel costs for integral pressurized water reactors are 15% to 70% higher than for large light water reactors, and points to research indicating similar comparisons for construction costs.20

International Atomic Energy Agency: The IAEA can usually be relied upon to parrot nuclear industry propaganda, but it states that "although SMRs require less upfront capital per unit, their electricity generating cost will probably be higher than that of large reactors".21

Massachusetts Institute of Technology: A 2018 MIT report states:22

"The main economic question is whether an SMR can be built at a substantially lower unit capital cost (i.e., per kW of capacity) and therefore generate baseload electricity at lower total unit cost (i.e., per MWh). NuScale advertises a capital cost of less than $5,100/kWe, which is only a modest improvement over the advertised cost of certain Gen-III+ systems and still not competitive against natural gas-fired generation under current circumstances. A 2016 study performed by Atkins for the U.K. government estimates the FOAK cost of power from integral PWR SMR designs to be about 30% above the NOAK cost of a traditional, large LWR. The Atkins study scales up companies' own capital cost estimates to correct for the 'optimism bias' discussed earlier, while also noting both the potential for sharp cost declines with volume production of factory builds and the enormous uncertainties involved in attempting to estimate this decline.

"Proponents of many small reactor designs also advertise other advantages besides lower capital costs. Some focus on the advantages of smaller total plant size. They point out that this opens up sections of the market that are unsuited to large LWRs of 1 gigawatt (GW) capacity or more. They also point out that buyers will be better able to finance capacity purchases in smaller bites.

"A note of caution is in order when evaluating claims concerning the ancillary advantages of small size. The challenge facing the nuclear industry is to reduce unit capital cost (i.e., cost per kWe) to be more competitive in generating the lowest unit cost electricity. If the size of a small plant also happens to be the size that offers the lowest unit capital cost, then the ancillary benefits of a smaller plant are an extra bonus. However, the extra advantages of small plant size are unlikely to make up for a failure to radically reduce unit capital cost.

"The problem is that, with respect to size, there is often a tradeoff between the technically optimal design and the needs of some customers. This is an age-old issue for the nuclear industry, as it is in many other industries. The optimally-sized reactor suits some segments of the market, but not all. Therefore, many reactor vendors size their technically optimal reactor first, and later produce smaller versions to serve segments of the market to which the most efficient design is not suited. Among LWR designs, examples of this approach include the Russian VBER-300, Holtec's SMR-160, and China's ACP1000.

"The industry's problem is not that it has overlooked valuable market segments that need smaller reactors. The problem is that even its optimally scaled reactors are too expensive on a per-unit-power basis. A focus on serving the market segments that need smaller reactor sizes will be of no use unless the smaller design first accomplishes the task of radically reducing per-unit capital cost. If nuclear technology cannot be competitive at its optimal scale of generation, whether large or small, it is difficult to see how it will succeed by scaling plants below the optimal size. If, on the other hand, smaller designs are optimal and can radically reduce unit capital costs, then the ancillary advantages of accessing a larger market will be a nice bonus."

Studies published in the Proceedings of the National Academy of Science

An article by four current and former researchers from Carnegie Mellon University's Department of Engineering and Public Policy, published in 2018 in the Proceedings of the National Academy of Science, argues that it is most unlikely that any new large nuclear power plants will be built over the next several decades in the US.23 "There is no reason to believe that any utility in the United States will build a new large reactor in the foreseeable future. These reactors have proven unaffordable and economically uncompetitive. In the few markets with the will to build them, they have proven to be unconstructible," M. Granger Morgan and his pro-nuclear colleagues state. "[T]here is virtually no chance that the United States will be able to undertake the construction of additional large LWR power plants in the next several decades," they add.

The authors further argue that no US advanced reactor design will be commercialized before mid-century and that the purported advantages of advanced reactor concepts "remain speculative". That leaves light-water SMRs as the only option that might be deployed at significant scale over the next few decades. They conclude: "We have systematically investigated how a domestic market could develop to support that [SMR] industry over the next several decades and, in the absence of a dramatic change in the policy environment, have been unable to make a convincing case."

On the use of SMRs for electricity generation (alone), the authors state:

"Our results reveal that while one light water SMR module would indeed cost much less than a large LWR, it is highly likely that the cost per unit of power will be higher. In other words, light water SMRs do make nuclear power more affordable but not necessarily more economically competitive for power generation. That vision of the dramatic cost reduction that SMR proponents describe is unlikely to materialize with this first generation of light water SMRs, even at nth-of-a-kind deployment.

"Because light water SMRs incur both this economic premium and the considerable regulatory burden associated with any nuclear reactor, we do not see a clear path forward for the United States to deploy sufficient numbers of SMRs in the electric power sector to make a significant contribution to greenhouse gas mitigation by the middle of this century."

The authors also systematically investigated how a domestic market could develop to support a SMR industry across a range of applications ‒ producing process heat for industrial applications; switching SMRs back and forth between electricity generation and water desalination to complement intermittent generation from renewable energy sources; and deploying SMRs as a source of electrical and thermal energy for US military bases. But none of those options show promise.

The authors state that subsidies amounting to several hundred billion dollars would be required to kick-start an SMR industry:

"Because the United States will probably not build any new large LWRs, and there is no practical way to bring advanced reactor designs to achieve widespread commercial viability in the United States in less than several decades, we have argued that only factory-manufactured SMRs could contribute a significant new nuclear carbon-free wedge on that time scale. For that to happen, several hundred billion dollars of direct and indirect subsidies would be needed to support their development and deployment over the next several decades, since present competitive energy markets will not induce their development and adoption."

A separate article published in the Proceedings of the National Academy of Science (with two of the same co-authors) points to dramatic variations in expert assessments of overnight constructions costs for integral light-water SMRs (overnight costs comprising the sum of engineering, procurement, and construction costs but excluding site-work, transmission up-grades and other "owner's costs", and the cost of financing).24 Further, the analysis considered a nth-of-a-kind plant and thus "assumed that the vendor has recouped the cost of design engineering and licensing, has exploited technological learning, and has streamlined construction management."

The authors concluded: "Consistent with the uncertainty introduced by past cost overruns and construction delays, median estimates of the cost of new large plants vary by more than a factor of 2.5. Expert judgments about likely SMR costs display an even wider range. Median estimates for a 45 megawatts-electric (MWe) SMR range from $4,000 to $16,300/kWe and from $3,200 to $7,100/kWe for a 225-MWe SMR."24

For a single 45 MWe reactor, 11 experts gave median costs between $4,000 and $7,700/kWe while five experts (four of them working for nuclear technology vendors) provided estimates as much as a factor of two to three higher. The authors state: "These five experts argued that costs rise rapidly as reactors become smaller, with the result that the 45-MWe reactor is especially disadvantaged."24

The article was published in 2013 and thus its conclusions can be reassessed in light of intervening events. In their 2013 article, the authors state that median estimates of the overnight cost of a 1,000-MWe reactor range from US$2,600 to US$6,600/kW.24 Yet in the 2018 article published in the Proceedings of the National Academy of Science, the authors note that the cost of the Vogtle AP1000 project in the US state of Georgia amounts to "a staggering $11,000 per kWe, and these costs are expected to rise".23

SMR projects won't be immune from the major cost overruns that have beset large reactors. Indeed cost overruns have already become the norm for SMR projects:

  • estimated construction costs for Russia's floating SMRs increased more than four-fold;
  • the estimated construction cost of China's demonstration HTGR is about twice the initial estimate; and
  • recent construction cost estimates for Argentina's CAREM SMR are 22 times greater than the number being floated in 2004 and the current estimate is a hopelessly uneconomic US$21,900 / kW (well outside the range suggested by the above-mentioned experts).


1. Charles Digges, 25 May 2015, 'New documents show cost of Russian floating nuclear power plant skyrockets',

2. OECD Nuclear Energy Agency, 2016, 'Small Modular Reactors: Nuclear Energy Market Potential for Near-term Deployment',

3. World Nuclear Association, Feb 2019, 'Nuclear Power in China',

4. 1 Dec 2016, 'China's plans to begin converting coal plants to walk away safe pebble bed nuclear starting in the 2020s',

5. World Nuclear Association, Feb 2019, 'Nuclear Power in China',

6. 7 Oct 2016, 'Gadano affirmed that 2,000 million pesos will be invested in the development of CAREM',

7. Darío Delmastro, Marcelo Oscar Giménez et al., January 2004, 'CAREM concept: A competitive SMR', Conference Paper, Argentina's Bariloche Atomic Center,

8. World Nuclear News, 10 Feb 2014, 'Construction of CAREM underway',

9. Andrew Baker, 17 April, 'Argentine nuclear reactor due to start up in 2020',

10. World Nuclear Association, January 2019, 'Nuclear Power in Argentina',

11. International Energy Agency (IEA) and OECD Nuclear Energy Agency (NEA), 2015, 'Projected Costs of Generating Electricity':

Media release:

Executive Summary:

Full report:

12. European Commission, 4 April 2016, 'Nuclear Illustrative Programme',

13. European Commission, 4 April 2016, 'Commission Staff Working Document, Accompanying the document: Communication from the Commission, Nuclear Illustrative Programme presented under Article 40 of the Euratom Treaty',

14. Atkins, 21 July 2016, 'SMR Techno-Economic Assessment Project 1: Comprehensive Analysis and Assessment Techno-Economic Assessment, Final Report, Volume 1, For The Department of Energy and Climate Change',

15. South Australian Nuclear Fuel Cycle Royal Commission Report, May 2016,

16. WSP / Parsons Brinckerhoff, Feb 2016, 'Quantitative analysis and initial business case – establishing a nuclear power plant and systems in South Australia',

17. Sonal Patel, 6 June 2018, 'NuScale Boosts SMR Capacity, Making it Cost Competitive with Other Technologies',

18. Mark Cooper, Sept. 2014, 'Small modular reactors and the future of nuclear power in the United States', Energy Research & Social Science, Vol.3, pp.161–177,

19. Mark Cooper, May 2014, 'The Economic Failure of Nuclear Power and the Development of a Low-Carbon Electricity Future: Why Small Modular Reactors Are Part of the Problem, Not the Solution',

20. Christopher P. Pannier and Radek Skoda, 2014, 'Comparison of Small Modular Reactor and Large Nuclear Reactor Fuel Cost', Energy and Power Engineering, 6, 82-94,

21. IAEA, 16 Feb 2018, 'IAEA Expands International Cooperation on Small, Medium Sized or Modular Nuclear Reactors',

22. Massachusetts Institute of Technology, 2018, 'The Future of Nuclear Energy in a Carbon-Constrained World: An Interdisciplinary MIT Study,

23. M. Granger Morgan, Ahmed Abdulla, Michael J. Ford, and Michael Rath, July 2018, 'US nuclear power: The vanishing low-carbon wedge', Proceedings of the National Academy of Science,

24. Ahmed Abdulla, Inês Lima Azevedo, and M. Granger Morgan, 2013, 'Expert assessments of the cost of light water small modular reactors', Proceedings of the National Academy of Science,