Environmental, Natural Resources, & Energy Law Blog

Micro Nuclear Reactors Can Help Solve the Climate Crisis

Bradley Newsad LLM ’23

Introduction

Climate change has forced the people and nations of the world to develop a net-zero carbon society as soon as sustainably possible.Many changes will need to be made, including a near elimination of greenhouse gas-producing energy production.Despite the controversy that nuclear energy has created in the past, given the dire circumstances some have advocated increasing nuclear energy production to help reduce greenhouse gases, including the use of new “micro” nuclear reactors.Private companies around the world are now designing and applying for construction and operating permits for microreactors.In addition to the usual nuclear energy production concerns, the potential use of microreactors raises several unique considerations.Given these concerns and considerations, are microreactors a viable clean energy source, and if so, to what extent?

Microreactors typically generate one to ten megawatts (MW) of electricity but are still considered “micro” up to at least 20 MW.[1]They are so small that many designs are portable by semi-tractor trailer, can be set-up in days, not years, and can be deployed on less than one acre of land.[2]By comparison, conventional nuclear reactors produce around 1,000 MW of electricity and typically require 1,000 to 7,000 acres of land and a major water source for cooling, which microreactors do not require.[3]Microreactors can provide relatively carbon-free energy production and their small size has unique benefits.They can be used to power remote areas, distinct complexes (e.g., universities, military bases, etc.), and areas suffering a sudden loss of power.Their small size also increases more conventional siting possibilities.

However, there are several potential limitations to microreactors.First, increasing nuclear energy production through microreactors will result in increased  uranium mining and processing, radioactive waste, and operational safety risks.Even with ideal environmental planning and design, these carry significant environmental risk.Second, while microreactors may be more efficient than large-scale reactors, they will likely require more uranium per unit of electricity generated, which would increase the mining, processing, and waste impacts.Third, the cost per unit of electricity may be higher than large-scale reactors.However, projections predict microreactors will be cheaper than current options in remote areas.Finally, an unfavorable stigma is attached to nuclear reactors, which for many people results in fear and opposition.Many, if not most people, will not want a nuclear reactor, micro or not, in their neighborhood.

Despite these challenges, the benefits outweigh the risks and microreactors should be seriously considered as part of the solution of reducing greenhouse gases.

Climate Change is now Climate Crisis

In its most recent science-based report, the Intergovernmental Panel on Climate Change (IPCC) determined that “[i]t is unequivocal that human influence has warmed the atmosphere, ocean and land.”[4]Human-produced greenhouse gases (GHG), chiefly carbon dioxide, have concentrated in the earth’s atmosphere, causing the global surface temperatures to rise more than 1.1ºC above the global average surface temperatures from pre-industrial levels.[5]The increase in global average temperature has caused many local, regional, and global impacts, most of which will be further exacerbated by increasing global surface temperatures.[6]These climate change impacts are profound and affect human health, livelihoods, infrastructure, the economy, and ecosystems, including plants, wildlife, and the marine environment.[7]

In order to halt and limit climate change, global GHG emissions need to approach net zero, a concept that requires balancing GHG emissions with GHG removals by natural and human processes.[8]The nations of the world agreed to limit the increase of the global average temperature to “well below 2ºC above pre-industrial levels” and to pursue efforts to limit the increase to 1.5ºC in the 2015 Paris Agreement to the United Nations Framework Convention on Climate Change.[9]

Much work is yet to be done.Global GHG emissions are currently projected to cause the global average temperature to exceed 1.5ºC this century based on individual national plans.[10]Limiting warming to below 2°C relies on a “rapid acceleration” of mitigation efforts in the next decade.[11]Much focus is on the energy supply sector because of its massive contribution to GHG emissions.In 2019, 34% of anthropogenic GHG emissions came from the energy supply sector.[12]Projected future GHG emissions over the lifetime of existing and currently planned fossil fuel energy production infrastructure exceeds the cumulative CO₂ emissions needed to limit warming to 1.5°C and are about equal to the cumulative CO₂ emissions needed to limit warming to 2°C.[13]This ignores all other GHG emission sources, which in 2019 accounted for 66% of all GHG emissions.As such, all GHG emission reduction efforts are important, but the energy supply sector is likely the most important.To be blunt, we are in a crisis mode and need to put all GHG emission reduction options on the table.

Micro Nuclear Reactors – the Benefits

Despite the concerns about nuclear energy, including radioactive pollutant contamination risk from uranium mining and reactor waste, and operational safety risks, the IPCC and others consider it to be an important mitigation option to reduce global GHG emissions.[14]Most importantly, nuclear power reactors do not directly produce GHG emissions.[15]However, mining and refining uranium for reactor fuel consumes energy, as does reactor facility construction.[16]But, any energy production facility will require energy consumption to build and maintain, so this is really a question of degree and comparison to other carbon-free energy supply sources.The small size of microreactors reduces energy use concerns associated with mining, refining, and construction.

Microreactors are so small that sitting possibilities are limited only by regulation and imagination.Of the more than 20 U.S. companies working on microreactor design, many are focused on remote areas currently powered by fuels, like diesel, that are subject to high transportation costs and risk of supply chain disruption.[17]Microreactors will be able to provide energy to these areas without the cost and risk of a constant supply chain.A one MW microreactor could supply power to 1,000 homes for 10 years or more before needing to be refueled.[18]

Other siting possibilities include distinct complexes, such as universities, hospitals, and military bases.[19]For example, The University of Illinois at Urbana-Champaign intends to apply for a microreactor construction permit with the aim of operating by early 2028.[20]Penn State University, which is collaborating with Westinghouse on microreactor technology, also hopes to have an operational microreactor by 2030.[21]The U.S. Department of Defense (DoD) is actively pursuing microreactor technology through Project Pele.[22]The project, for which the DoD issued a final environmental impact statement and record of decision in February and April of 2022, respectively, involves construction of a transportable 1-5 MW microreactor powered by tristructural isotropic (TRISO) fuel, which has the potential to reduce operational and security risk concerns.[23]Additionally, the DoD asserts its mobile microreactors could be transported to military installations and civilian settings to supply energy to critical infrastructure, like hospitals, following natural disasters.[24]The application of microreactor energy supply following a sudden loss of power can be used beyond the DoD and natural disasters.

For the above reasons, microreactors are a viable energy source in the face of climate change.However, their use will likely be limited because of their actual and perceived drawbacks.

Micro Nuclear Reactors – the Potential Drawbacks

Increasing nuclear energy production in any form, including microreactors, will result in increased uranium mining and processing, radioactive waste, and operational safety risks.Regardless of careful environmental planning and design, each of these is problematic.As the U.S. Environmental Protection Agency (EPA) states on its website, uranium extraction “leave[s] behind radioactive waste.”[25]The EPA reports that “[w]ind can blow radioactive dust from the wastes into populated areas and the wastes can contaminate surface water used for drinking. Some sites also have considerable groundwater contamination.”[26]And while the EPA touts that uranium decays to radium, which decays to radon, which “disperses into the atmosphere,” posing no ”significant” risk to the public, the most common uranium isotope (²³⁸U) has a half-life of 4.5 billion years.[27]Thus, little safety or solace is provided by radioactive decay to radon.

The handling and treatment of radioactive waste requires national-level policy decisions including, specifically whether to treat spent nuclear fuel strictly as “waste” or whether to recycle as much as 97% for re-use in nuclear energy production.[28]Radioactive spent nuclear fuel is particularly problematic in the U.S. because it is treated as waste but there is no national storage facility.[29]As such, radioactive spent fuel is stored on-site at the 55 nuclear power plants operating throughout 28 states.[30]That means that society relies on the nuclear industry and government regulatory oversight to ensure 55 separate sites carefully and properly handle their waste, rather than one federally controlled site.Other countries, including France, Japan, Germany, and Belgium, recycle as much as 97% of their spent nuclear fuel, immobilizing and storing the remaining small portion of waste.[31]Microreactors will need to be treated differently in the U.S.Because microreactors can be mobile and deployed on less than one acre of land, on-site storage of spent fuel will not be an option.Either way, treatment and storage of spent nuclear fuel is a considerable environmental concern given the possible impacts of mishandling.

Operational safety risks fall into at least three categories: (1) operator failure (e.g., 1979 Three Mile Island accident, 1986 Chernobyl accident) leading to a radioactive release, (2) structural failure caused by a natural disaster (e.g., 2011 Fukushima disaster) leading to a radioactive release, and (3) a physical attack leading to either a radioactive release or the theft of nuclear fuel that could be used in a subsequent nuclear attack.[32]Nothing about the design or operation of microreactors eliminates any of these risks.Instead, the risk of physical attack and nuclear fuel theft is likely higher because (1) small, mobile microreactor sites will arguably be more difficult to protect and (2) most microreactor designs use high-assay low-enriched uranium (HALEU) fuel, which despite its name, can be up to four-times more “enriched” than nuclear fuel used in existing reactors, making it more attractive for theft.[33]However, new fuel cell designs to be used in some microreactors, such as TRISO fuel, reduce both the chance and impacts of operator failure, as well as the impacts of a structural failure.[34]Regardless, microreactors remain susceptible to all three types of operational safety risks.

One interesting connection between the spent nuclear fuel conundrum and the development of HALEU fuel is that there is doubt about the U.S.’s ability to meet the demand for HALEU fuel by the end of the decade.[35]The U.S. Department of Energy is currently exploring two different solutions to prevent a HALEU fuel shortfall both involving recycling spent nuclear fuel from government-owned research reactors.[36]While this current plan is limited, it could spur greater interest in recycling spent nuclear fuel in the U.S.

The specifics of reactor efficiency can be complicated.The relevant question is whether microreactors require and use more uranium per unit of electricity generated over the course of a reactor’s life as compared to large-scale reactors.If so, this would increase the impacts of uranium mining and processing, and the handling of spent nuclear fuel.Because microreactors are small, they require a higher-enriched uranium fuel so that they can produce more thermal energy per unit of reactor core volume (microreactors could require up to four times as much uranium-235 by fuel mass).[37]Assuming all microreactor uranium fuel is sourced by mining, uranium mining will increase to produce the same amount of fuel.[38]Another important consideration is the overall thermal and net efficiency of a nuclear power plant.Microreactor designs will likely be more efficient than older large-scale reactors.[39]This means that microreactors will convert more of the thermal energy they produce into electrical energy as compared to large-scale nuclear reactors.However, microreactor efficiency improvement is likely to be less than an order of two.[40]Thus, when compared to the increased uranium enrichment (up to a factor of four), it appears that microreactors will indeed require more uranium per unit of electricity generated.[41]

The comparison of cost per unit of energy generated between nuclear power and other sources varies, but generally it is competitive.[42]Comparing microreactors to large-scale reactors, the U.S. Government Accounting Office (GAO) suggests that cost efficiencies will be created through greater economies of scale, as microreactors could be factory assembled.[43]Recent examples demonstrate this point – two new large-scale reactors (1117 MW each) coming online this year in the state of Georgia cost more than a combined $34 billion to build; conversely, Last Energy, a Washington D.C.-based company planning to build microreactors, reports that their 20 MW microreactor costs less than $100 million, including assembly and deployment.[44]The comparison is not close – the Georgia plants cost more than $15 million/MW versus $5 million/MW for Last Energy’s microreactor. However, the two Georgia plants were only supposed to cost $14 billion – reducing the cost to under $6.5 million/MW.[45]With microreactors still in the early stages of production, it is very possible that they may experience cost overruns as well.Comparing microreactors to their unique competition in remote areas, U.S. Government-cited projections predict that microreactors will be cheaper than diesel generators in remote parts of Alaska.[46]But as the U.S Government concedes, these are merely projections, and the actual costs are still uncertain.

Finally, the stigma of “nuclear” energy need not be belabored.In a nation where wealthy islanders successfully battered and wore out a commercial enterprise attempting to build an offshore wind farm nearly 5 miles from the island because it was “unsightly” and would “negatively affect[] tourism and property values,”[47] it’s not hard to imagine local challenges to microreactor siting.The so-called NIMBY (not-in-my-back-yard) contingent will likely be a difficult challenge to overcome in many areas.

Conclusion

Microreactors are a viable clean energy source in the face of climate change because they provide carbon-free energy production and their small size has several unique benefits.However, their use will likely be relatively limited to niche applications, such as remote areas, distinct complexes, and disaster deployment.Microreactors will suffer many of the same challenges as large-scale reactors – the need for uranium mining and processing, the handling and disposition of radioactive waste, and operational safety risks.Relative costs are still uncertain; as the technology further develops, the cost factor could have a positive or negative impact on the industry.And the unfavorable stigma attached to nuclear reactors will continue to be a difficult challenge.Nevertheless, given the climate crisis, governments should facilitate the utilization of microreactors in the effort to achieve a net-zero carbon world as soon as possible.