In 1942 in a laboratory beneath the bleachers of the University of Chicago’s football field, Enrico Fermi and a team of scientists set the first man-made, self-sustaining nuclear chain reaction into motion. 

In 1960, 18 years later and two hours south, the University of Illinois (UIUC) launched TRIGA, an on-campus nuclear research reactor that operated for 38 years. In 2015, the American Nuclear Society honored TRIGA with the Nuclear Historic Landmark Award in recognition of its “instrumental [role] in the advancement and implementation of nuclear technology.”   

Today, Illinois remains a national nuclear energy leader, generating more electricity from nuclear power than any other state. In 2020, Illinois’s six nuclear plants accounted for 58 percent of the state’s net electricity generation, whereas other forms of carbon-free energy such as wind and solar accounted for 11 percent.

According to the Environmental and Energy Study Institute, the Midwest emits 22 percent more carbon per capita than the U.S. average. Illinois’s large nuclear energy infrastructure, however, has allowed it to keep per capita energy-related carbon emissions lower than most other Midwestern states. According to the Energy Information Administration, in 2016, the average Illinoisian emitted 15.9 metric tons of carbon throughout the year. Indiana, Iowa, Ohio and Wisconsin had average per capita energy-related carbon emissions of 27.4, 23.4, 17.7 and 17.3 metric tons, respectively. 

Energy-related emissions can come from industry and fuel as well, but for many states, generating electricity accounts for a large percentage of carbon emissions. In Indiana and Ohio, it was responsible for 46 and 39 percent of energy-related carbon emissions in 2016, respectively. That means cutting down on carbon generation in the electricity sector—whether by using nuclear energy, renewables like wind and solar, or a combination—would be transformative to many states’ energy systems. 

Historically, however, concerns about potential hazards associated with nuclear energy have hindered its development. Public trust in nuclear has been undermined by high-profile accidents at nuclear plants that resulted in radioactive leakage, extreme public health hazards and environmental damage. According to Bulletin of the Atomic Scientists, Americans respond quite differently to questions about nuclear energy depending on the context; many say they don’t understand the technology very well. 

In Illinois, where nuclear energy generates a disproportionate amount of electricity, political and corporate disagreements have rendered the future of several nuclear plants uncertain. 

“If carbon generation is a concern, then those [nuclear plants] have to stay safely operated,” Caleb Brooks, a professor in University of Illinois Urbana-Champaign’s (UIUC) Department of Nuclear, Plasma and Radiological Engineering, said. “Existing nuclear reactors have done a great job of providing carbon-free electricity for the U.S. for quite a long time now.”

Cooling towers at Exelon’s Byron Generating Station. Illinois leads the nation in energy generation from traditional nuclear power. Image courtesy of Christopher Peterson.

Brooks also said there’s been significant advancements in nuclear technology in the last several decades, mostly focused on developing reactors that function more safely and efficiently than those traditional ones. Developing reactors of the future is the main focus of his work at UIUC’s Department of Nuclear, Plasma and Radiological Engineering. 

Traditional nuclear reactors—sometimes called “light-water reactors” since they use water as a coolant—are based on technology from the 1960s and 1970s, Brooks said. Uranium, their fuel, is packed together then submerged in water. The uranium undergoes a nuclear fission reaction, wherein atoms split, releasing energy that heats up the water and creates steam. That steam is used to turn a turbine, generating electricity.

Model of a traditional nuclear reactor, also called a light-water reactor. Image courtesy of U.S. Office of Nuclear Energy.

Government officials, engineers and scientists, however, have been working to develop different types of nuclear reactors for decades. In 2001, 13 countries came together to form the Generation IV International Forum, which aims to create safer, more efficient nuclear systems that could be commercially deployed by 2030. One of those potential systems is a microreactor that was designed by the Ultra Safe Nuclear Corporation (USNC). 

Now, in a major step towards bringing Gen. IV-reactors out of the imagination and into the real world, UIUC is looking to build USNC’s microreactor on their campus. On June 28, UIUC submitted a Letter of Intent to the U.S. Nuclear Regulatory Commission applying for a license to do just that. Brooks said the project would focus on training students to work with Gen. IV nuclear technology and moving advanced nuclear closer to commercial availability. 

The type of Gen. IV microreactor UIUC is looking to build would have several features differentiating it from traditional nuclear reactors. Two of those differences—the amount of energy it generates and the type of fuel it uses—are geared toward avoiding meltdowns.

“If you can minimize the amount of energy that’s there, then it’s harder to melt,” Brooks said. “Traditional light-water reactors that have had partial meltdowns… are operating usually at around 3000 megawatts. In the case of microreactors, particularly USNC’s design that we’re exploring for our campus, they’re only at 15 megawatts.”

At the same time, the microreactor uses fuel that can withstand higher temperatures without melting. It operates for 20 years and doesn’t need to be refueled. Because of its small size and modular form, transporting a new fuel cartridge to replace the old one poses minimal challenges. Brooks said he thinks that in the coming decades, researchers and policymakers could likely find ways to recycle, reprocess or repurpose the materials in spent fuel cartridges.

“The idea for microreactors is that everything can be factory-fabricated,” Brooks said. “You can deliver it to a site, drop it down, and then instead of having years of on-site construction, maybe you have a month or less of on-site assembly.”

That makes Gen. IV microreactors ideal for carbon-free energy generation in remote areas that can’t be easily connected to the broader electrical grid, or for use as generators at hospitals or essential industries that require a constant flow of electricity. This is especially important for the Midwest, where manufacturing is still the largest industry; in states like Indiana and Ohio, industry accounted for 23.1 and 17.2 percent of energy-related carbon emissions in 2016, respectively. If Gen. IV microreactor technology were to become commercially available, manufacturing plants throughout the region could drastically reduce their carbon emissions.

 The microreactor also stores energy in molten salt tanks. It’s constantly generating energy, but during downtimes when energy isn’t being immediately used, the system can store excess as heat until energy use increases again. Brooks said this feature is valuable in a broader energy system that increasingly relies on wind and solar. 

“Wind and solar are very intermittent,” Brooks said. “With solar it’s quite obvious—at night, you don’t have any solar irradiance, and so you’re not going to produce any power. But even wind can be very intermittent… sometimes [the turbines] are spinning, sometimes they’re not. And so what the molten salt loop does… is allow the reactor to stay pretty independent of that demand.”

This means that Gen. IV nuclear reactors could fill gaps within renewable energy systems, as states could continue to expand solar and wind capacity while also relying on Gen. IV nuclear reactors to provide energy during downtimes or to facilities like hospitals or industrial plants that require a constant stream of energy. Brooks said building a microreactor on UIUC’s campus will bring the U.S. closer to creating this type of integrated energy system.

“Within our project, we’ve been thinking about research a little differently than traditional university-based nuclear reactors,” Brooks said. “The research that we’re excited about here is the research that is necessary to see the technology be more widely adopted.”

Brooks said research would examine how a Gen. IV microreactor interacts with the larger energy grid, especially one that includes fossil fuels as well as wind and solar farms. For nuclear energy development to continue improving, however, Brooks said government support for innovation will be essential, especially since nuclear research is heavily restricted by regulation.

“In the case of nuclear technology, all roads go through the Department of Energy,” Brooks said. “The timeline of [nuclear] innovation [is] very different because folks… don’t have the same freedom to go out and test that technology.”

Brooks said he was encouraged to see that in May of 2021, the Department of Energy proposed $1.8 billion in funding for the Office of Nuclear Energy. The proposal, which currently awaits congressional approval, would represent a 57 percent increase in funding since 2021 for the Office. Brooks said projects like UIUC’s can provide invaluable opportunities to start developing a workforce that’s educated in operating new nuclear technologies and can help scale them in coming years. 

“[Right now] that workforce doesn’t exist [enough] for these technologies to really proliferate around the country and around the world,” Brooks said. “So this is the time to invest in campuses… and really develop a public literacy around advanced nuclear.”


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