An academic reactor or reactor plant almost always has the following basic characteristics:	On the other hand, a practical reactor plant can be distinguished by the following characteristics:
(1) It is simple. (2) It is small. (3) It is cheap (4) It is light. (5) It can be built very quickly. (6) It is very flexible in purpose (’omnibus reactor’). (7) Very little development is required. It will use mostly off-the-shelf components. (8) The reactor is in the study phase. It is not being built now.	(1) It is being built now. (2) It is behind schedule. (3) It is requiring an immense amount of development on apparently trivial items. Corrosion, in particular, is a problem. (4) It is very expensive. (5) It takes a long time to build because of the engineering development problems. (6) It is large. (7) It is heavy. (8) It is complicated.
Admiral Hyman Rickover, June 1953

The overblown hype of the nuclear "bros"
Small modular reactors are not more economical than large reactors.
They are not generally safer or more secure.
They will not reduce the problem of nuclear waste.
They can't be counted on to operate without reliable access to grid power.
They do not use fuel more efficiently than large reactors.
By Ed Lyman, Union of Concerned Scientists, April 30, 2024

Small Modular Reactors: the last-chance saloon for the nuclear industry? The claims being made for SMRs, analyzed in this article, will be familiar to long-time observers of the nuclear industry: costs will be dramatically reduced; construction times will be shortened; safety will be improved; there are no significant technical issues to solve; nuclear is an essential element to our energy mix. In the past such claims have proved hopelessly over-optimistic and there is no reason to believe things would turn out differently this time. Indeed, the nuclear industry may well see itself in the ‘last-chance saloon’. The risk is not so much that large numbers of SMRs will be built, they won’t be. The risk is that, as in all the previous failed nuclear revivals, the fruitless pursuit of SMRs will divert resources away from options that are cheaper, at least as effective, much less risky, and better able to contribute to energy security and environmental goals. Given the climate emergency we now face, surely it is time to finally turn our backs on this failing technology? By Steve Thomas, Emeritus Professor of Energy Policy at Greenwich University, UK. Scientists for Global Responsibility, issue 5, March 14, 2023

Native American tribes oppose Small Modular Nuclear Reactors at Hanford:: Confederated Tribes of the Umatilla Indian Reservation and Confederated Bands and Tribes of the Yakama Nation February 2024

Developer of next-generation nuclear power plants pulls plans for project in Washington X-energy, a company developing a new generation of smaller nuclear power plants, has pulled its plans to build the company’s first demonstration project in Washington state. Nearly two years after X-energy announced that Grant County would take an ownership stake in the 320-megawatt project, a site location had yet to be determined. The sponsors claim an unrealistically low price of $2.2 billion (half of it to be government subsidized), especially for a design not yet federally licensed. This, despite the fact that the game was to be played on the industry's home court, the Hanford Nuclear Reservation. By Hal Bernton, Seattle Times, March 2, 2023
Update: A Grant County PUD spokesperson announced that the public utility district in central Washington has withdrawn from a planned collaboration with the Maryland-based company X-energy to build an SMR-based nuclear power plant. Columbia Insight, January 11, 2024

Time isn't on their side With the exception of the NuScale reactor design, which is based on the traditional light water reactor, many of the remaining American SMRs on the drawing board would use High Assay Low Enriched Uranium (HALEU) fuel, something only Russia commercially manufactures currently. (The “low enriched” in the name is misleading as the uranium is actually enriched to close to 20% which borders on weapons-usable.) The need to import HALEU from Russia has suddenly prompted an attack of conscience in at least one quarter. “We didn’t have a fuel problem until a few months ago,” Jeff Navin, director of external affairs of the Bill Gates-owned company TerraPower told Reuters. “After the invasion of Ukraine, we were not comfortable doing business with Russia.” But retooling the industry for the domestic production of HALEU fuel will not be straightforward and developing it will put an unpredictable but significant delay on the climate goals for the US SMR program. This presents a conundrum perfectly described by the chief executive of U.S. nuclear fuel supplier Centrus Energy Corp., in the same Reuters article. “Nobody wants to order 10 reactors without a fuel source, and nobody wants to invest in a fuel source without 10 reactor orders,” he said. Beyond Nuclear International, November 20, 2022

The Impossible Promises of Small Modular Nuclear Reactors Billionaires might throw their money after small modular reactor designs, but the SMR claims are flawed and misleading. The multiple problems of SMRs, including economics, timelines, proliferation and waste, have not been resolved despite the hype. Governments should stop wasting money on them. By M.V. Ramana, Peace Magazine, July 21, 2022

Nuclear waste from small modular reactors  The low-, intermediate-, and high-level waste stream of SMRs will produce more voluminous and chemically/physically reactive waste than light water reactors, which will impact options for the management and disposal of this waste. The intrinsically higher neutron leakage associated with SMRs suggests that most designs are inferior to LWRs with respect to the generation, management, and final disposal of key radionuclides in nuclear waste. By Lindsay Krall, Allison Macfarlane, and Rodney Ewing, Proceedings of the National Academy of Sciences (US), May 31, 2022

Stanford-led research finds small modular reactors will exacerbate challenges of highly radioactive nuclear waste Small modular reactors, long touted as the future of nuclear energy, will actually generate more radioactive waste than conventional nuclear power plants, according to research from Stanford and the University of British Columbia. Stanford News, May 30, 2022 [Summary]
Complete text here

How to Speed Up the Rollout of Small Nuclear Power Plants
The article's lead:
> The invasion of Ukraine has put the U.S. and Europe on a wartime mission to abandon Russian fossil fuels. ...
> As Russia’s war in Ukraine galvanizes Western countries to break their reliance on Russian energy exports, in part by accelerating green technologies that will replace fossil fuels, one solution could be boosting the deployment of nuclear energy.
But it goes on:
>  However, the type of fuel its reactor would run on is scarce—and mostly sourced from Russia right now. A domestic supply would take years to jump-start.
   So much for that justification.

U.S. nuclear power agency seeks documentation of NuScale's quake protection An agency engineer raised questions about the company's reactor design's ability to withstand earthquakes. Reuters, April 28, 2022

Small modular reactors offer no hope for nuclear energy The economics will only be tested when large numbers of reactors manufactured on production lines have been built and their cost known. Private industry is not going to take the risk of paying for production lines and buying large numbers of reactors that could well prove uneconomic. So, it will be public money, as it nearly always has been the case with nuclear power, that will be risked. Meanwhile, as reactor costs have been rising relentlessly for decades, costs of renewables are now far lower than for nuclear power. By M.V. Ramana, January 14, 2022

Mobile Nuclear Reactors Won't Solve the Army's Energy Problems The Army appears set to credulously accept industry claims of complete safety that are founded in wishful thinking and characterized by willful circumvention of basic design safety principles. By Jake Hecla, December 14, 2021

Small Modular Nuclear Reactors proposed for Hanford nuclear reservation X-energy Company proposes to site a small modular nuclear reactor at Energy Northwest’s campus. As usual with this type of development, its prospects depend heavily on government subsidies - money which could be used much more quickly and effectively to build safe, clean renewable energy sources like wind and solar power. The cost of battery storage will be much less than the cost of building more nuclear power plants. Columbia Riverkeeper, September 2021
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An Open Letter to Bill Gates About his Wyoming Atomic Reactor Gates has received government subsidy to build a sodium-cooled "Natrium" modular nuclear reactor. He does not appear to be aware of that type of reactor's 70-year record of failure. (See also the analysis of sodium-cooled reactors by the Union of Concerned Scientists .) By Arnie Gunderson, August 20, 2021

"Advanced" Nuclear Reactors? Don't Hold Your Breath With little hard evidence, their developers maintain they’ll be cheaper, safer, and more secure than existing power plants. By Elliott Negin, Scientific American, July 23, 2021

Why Small Modular Reactors Won't Help Counter the Climate Crisis Two main reasons: Time and cost. Furthermore, if an error in a mass-manufactured reactor were to result in safety problems, the whole lot might have to be recalled. But how does one recall a radioactive reactor? And what will happen to an electricity system that relies on identical reactors that need to be recalled? These questions haven’t been addressed by the nuclear industry or energy policy makers – indeed, they have not even been posed. Yet recalls are a predictable and consistent feature of mass manufacturing, from smartphones to jet aircraft. By Arjun Makhijani and M.V. Ramana, Environmental Working Group, March 25, 2021

Debunking the myths around Small Modular Nuclear Reactors One and a half hour video presentation by Beyond Nuclear, the Coalition for Responsible Energy Development in New Brunswick, and the Canadian Environmental Law Association. October 21, 2020
The speakers' PowerPoint presentations are available here.

Two's a crowd: Nuclear and renewables don't mix - differences in carbon emissions reduction between countries pursuing renewable electricity versus nuclear power. If countries want to lower emissions as substantially, rapidly and cost-effectively as possible, they should prioritize support for renewables, rather than nuclear power, the findings of a major new energy study conclude. ScienceDaily, October 5, 2020

Nuclear energy is more expensive than renewable energy Last November, the Wall Street advisory firm Lazard reported that the average construction costs of solar photovoltaics and onshore wind turbines in the United States—one of the largest renewable energy markets in the world—are $1,000 and $1,300 per kilowatt of generation capacity respectively, down from $1,750 per kilowatt for either technology in 2013. During this period, the cost of building a new nuclear reactor rose from $6,792 to $9,550 per kilowatt. By M.V. Ramana, University of British Columbia, September 22, 2020

Smaller, cheaper reactor aims to revive nuclear industry, but design problems raise safety concerns Reviewers have unearthed design problems, including one that critics say undermines NuScale's claim that its SMNR would shut itself down in an emergency without operator intervention. Science Magazine, August 18, 2020

The SMNR ‘hype cycle’ hits a hurdle in Australia The three stages of the cycle:
   1. Vendors produce low-cost estimates.
   2. Advocates offer theoretical explanations as to why the new nuclear technology will be cost competitive.
   3. Government authorities bless the estimates by funding studies from friendly academics.
Then, of course, costs go up and construction takes much longer than projected. Now, the self-referential SMNR hype cycle has been disrupted in Australia by two government agencies. By Jim Green, Nuclear Monitor #886, June 8, 2020

A Critical Analysis of the Nuclear Waste Consequences for Small Modular Nuclear Reactors Small Modular Nuclear Reactors (nuclear reactors with electric capacities less than 300 MW) have received support on the pretense that their development will reduce the mass and radiotoxicity of commercially generated nuclear waste. By analyzing the published design specifications for water-, sodium-, and molten salt-cooled SMNRs, I here characterize their notional, high-level waste streams in terms of decay heat, radiochemistry, and fissile isotope concentration, each of which have implications for geologic repository design and long-term safety. Volumes of low- and intermediate-level decommissioning waste, in the form of reactor components, coolants, and moderators, have also been estimated.
*  The results show that SMNRs will not reduce the size of a geologic repository for spent nuclear fuel, nor the associated future dose rates.
*  Rather, SMNRs are poised to discharge spent fuel with relatively high concentrations of fissile material, which may pose re-criticality risks in a geologic repository.
*  Furthermore, SMNRs entail increased volumes of decommissioning waste, as compared to a standard 1100 MW, water-cooled reactor.
Hour-long video presentation By Dr. Lindsay Krall, Stanford University, June 4, 2020

Small Modular Nuclear Reactors, a case of wishful thinking at best SMNR projects are looking more like a way to funnel money to the sagging nuclear industry than to generate power. Unfortunately, they take money away from legitimate the clean energy projects needed to combat climate change. By Gordon Edwards, Canadian Coalition for Nuclear Responsibility, December 18, 2019

Seven reasons why Small Modular Nuclear Reactors are a bad idea for Australia Cost, safety, security, weapons proliferation, wastes, location, delay. By Noel Wauchope, Independent Australia, August 17, 2019

Prospects for Small Modular Nuclear Reactors in the UK & Worldwide There are huge obstacles in the path of development of SMNRs, including technical issues, building up an effective supply chain, and financing, which will only be possible with public subsidies. These issues are examined in detail in this report, which concludes that SMNRs will not be built in any significant scale. By Steve Thomas, Paul Dorfman, Sean Morris, and M.V. Ramana, Nuclear Consulting Group (UK), July 2019

Small Modular Nuclear Reactors and why we don’t need them A fact sheet synthesizing many of the long reports on the downsides of the SMNR. By Beyond Nuclear, April 2019

An obituary for Small Modular Nuclear Reactors
* The enthusiasm for SMNRs has little to do with climate-friendly environmentalism. About half of the SMNRs under construction (in Russia and China) are designed to facilitate access to fossil fuel resources in the Arctic, the South China Sea, and elsewhere. In Canada, one application under consideration is to provide power and heat for the extraction of hydrocarbons from oil sands.
* Another feature of the SMNR universe is its deep connection with militarism, as this article describes.
* The power produced by SMNRs will almost certainly be more expensive than that produced by large reactors.
* No company, utility, consortium or national government is seriously considering building the massive supply chain that is at the very essence of the concept of SMNRs - mass, modular factory construction. Yet without that supply chain, SMNRs will be expensive curiosities.
By Jim Green, The Ecologist , March 11, 2019

Scientists assessed the options for growing nuclear power They are grim. Under every plausible scenario, power from SMNRs is (and remains, even with subsequent generations of the tech) substantially more expensive than power from competitors. By David Roberts, Vox, July 11, 2018

Exelon: No new nuclear power units will be built in US This includes Small Modular Nuclear Reactors, seen as too expensive, due to size and security requirements. Exelon is the largest electric utility holding company and the largest nuclear generator in the US. Platts, April 12, 2018

Comments to Los Alamos County Council (NM) on UAMPS (Utah Associated Municipal Power Systems) Small Modular Nuclear Reactor Project UAMPS and the County Council refer to the proposed UAMPS SMNR Project as Carbon Free Power Project, yet there is no information in support of that very misleading description. Power, most likely derived from fossil fuel, is used for uranium mining and milling, uranium conversion and enrichment, fuel fabrication, fabrication and construction of the SMNR, operation of the SMNR, used fuel storage, irradiated fuel disposition, transport (road, rail, and ocean shipping), and myriad other aspects of the nuclear fuel chain necessary to license, fabricate, construct, and operate a reactor and the irradiated fuel storage site it will become. “Carbon Free Power Project” is an egregious public relations misnomer leading to false assumptions and poor decisions. By Sarah Fields, Program Director, Uranium Watch, February 14, 2018

Power from mini nuclear plants "would cost more than from large ones" A UK study found that electricity from Small Modular Nuclear Reactors would cost nearly one-third more than from plants such as Hinkley Point C, which is already the most expensive ever ordered. Meanwhile, as the UK government continues to spend huge amounts subsidizing expensive nuclear power, without adequate support for solar and wind energy, it has been unable to find a community interested in hosting a long-term underground nuclear waste dump. The Guardian (UK), December 7, 2017

Small nuclear reactors  are a 1950s mirage come back to haunt us The UK government proposes a 250 million pound subsidy to develop SMNRs, but by 2050 they will be 50-100 times more expensive than solar. By Oliver Tickell, The Ecologist (UK), October 24, 2017

Small Modular Nuclear Reactors and the Challenges of Nuclear Power Any attempt to deal with the problems of safety, proliferation resistance, decreased generation of waste, and cost reduction has to be reflected in some fashion in the design of specific nuclear reactors. But it turns out that each of these priorities can drive the requirements of the reactor design in different, sometimes opposing, directions.
SMNRs miss out on what are called economies of scale: the advantages that come with costs scaling more slowly than output power. For example, a 1000 MW reactor does not require four times as much concrete as a 250 MW reactor. Designers hope that this negative effect possibly could be offset somewhat through economies of mass manufacture. But even with optimistic assumptions about learning rates, hundreds, if not thousands, of reactor units would have to be built in order for mass manufacture effects to counteract the loss of economies of scale.
By M.V. Ramana and Zia Mian, Princeton University, January 2017

US Government Accountability Office pours cold water on advanced reactor concepts SMNRs require additional technical and engineering work to demonstrate reactor safety and economics. These challenges may result in higher cost reactors than anticipated, making them less competitive with large light-water reactors. Nuclear Monitor, September 9, 2015

The Forgotten History of Small Nuclear Reactors Small nuclear reactors have historically suffered from poor economics as well as technical problems. Without exception, they have cost too much for the little electricity they have produced. By M. V. Ramana, Princeton University, April 2015 (PDF)

Small Modular Nuclear Reactors: a chicken-and-egg situation A review of their inability to gain traction. Nuclear Monitor, March 19, 2015

Nuclear Power: A risky wager for the Pacific Northwest Running an aging nuclear plant and building new, modular ones is a gamble for Washington State. By Bruce Amundson and Chuck Johnson, Crosscut, September 11, 2014

What went wrong with SMNRs? Something happened on the way to the modular reactor promised land. Over the past year, the SMNR industry has been bumping up against an uncomfortable and not-entirely-unpredictable problem: It appears that no one actually wants to buy one. By Thomas Overton, POWER Magazine, September 1, 2014

One size doesn’t fit all: Social priorities and technical conflicts for Small Modular Nuclear Reactors Small Modular Nuclear Reactors (SMNRs) have been proposed as a possible way to address the social problems confronting nuclear power, including poor economics, the possibility of catastrophic accidents, radioactive waste production, and linkage to nuclear weapon proliferation. Several SMNR designs, with diverse technical characteristics, are being developed around the world and are promoted as addressing one or more of these problems. This paper examines the basic features of different kinds of SMNRs and shows why the technical characteristics of SMNRs do not allow them to solve simultaneously all four of the problems identified with nuclear power today. It shows that the leading SMNR designs under development involve choices and trade-offs between desired features. Focusing on a single challenge, for example cost reduction, might make other challenges more acute. The paper then briefly discusses other cultural and political factors that contribute to the widespread enthusiasm for these reactors, despite technical and historical reasons to doubt that the promises offered by SMNR technology advocates will be actually realized. By M.V. Ramana and Zia Mian, Energy Research and Social Science, May 24, 2014

Your choice: small reactors or carbon reductions. You can't have both. A newly-released study asserts that large-scale development of “Small Modular Nuclear Reactors” (SMNRs) likely would cost $90 Billion – an amount that likely would be diverted from development of much more cost- and climate-effective renewable energy. May 15, 2014
The full report:
The economic failure of nuclear power and the development of a low-carbon electricity future: Why Small Modular Nuclear Reactors are part of the problem, not the solution By Mark Cooper, Ph.D., Institute for Energy and the Environment, Vermont Law School, May 2014

Squandering Money and Resources Sierra Club fact sheet on Small Modular Nuclear Reactors, 2014

Why Nuclear Power Fails Jeremy Rifkin, President of the Foundation on Economic Trends, speaks at the Wermuth Asset Management 5th Annual Investors Event regarding nuclear power and its fate in the future of renewable energy, offering several reasons to avoid nuclear investments, including:
* Nuclear power can't be scaled up enough to have an impact on climate change.
* No solution has been found for the disposal of nuclear waste.
* Even with existing plants, there will be a uranium deficit in the not-distant future.
* Water to cool the power plants is in short supply - over 40% of all fresh water used in France is used to cool nuclear plants.
* The centralized power-plant paradigm is outdated. The future is bringing distributed generation.
Video (4 minutes), published October 8, 2013

Light Water Designs of Small Modular Nuclear Reactors: Facts and Analysis This paper discusses why SMNRs are a poor bet to solve the financial and safety problems of present-day commercial nuclear power reactors. By Arjun Makhijani, Institute for Energy and Environmental Research, September 2013

Small Modular Nuclear Reactors: Safety, Security, and Cost Concerns This article examines the various concerns and concludes that small reactors are unlikely to solve the economic and safety problems faced by nuclear power. Union of Concerned Scientists, September 2013

Small Isn't Always Beautiful Safety, Security, and Cost Concerns about Small Modular Nuclear Reactors. By Edwin Lyman, Senior Scientist, Union of Concerned Scientists, 2013 (PDF)

Does DOE’s Funding Announcement Mark the End of its Irrational Exuberance for Small Nuclear Reactors? By Edwin Lyman, Union of Concerned Scientists, November 21, 2012

Small Modular Nuclear Reactors: No Solution for the Cost, Safety, and Waste Problems of Nuclear Power By Arjun Makhijani and Michele Boyd, Physicians for Social Responsibility and Institute for Energy and Environmental Research, September 2010 (PDF)

“New” Nuclear Reactors: Same Old Story Why Small Modular Nuclear Reactors (and other newly-promoted concepts) will not work. By Amory Lovins, Rocky Mountain Institute, June 2009