Tomorrow’s advanced reactors require high-fidelity modeling and rigorous analysis from experts at Argonne National Laboratory, where the nation has made some of its most important discoveries about nuclear energy.
In May, the United States took another step toward building the country’s first advanced nuclear reactors at an industrial site. The project at a chemical plant in southeast Texas includes four small modular reactors being developed with support from the U.S. Department of Energy’s (DOE’s) Argonne National Laboratory.
Reactor developer X-energy is one of several American companies that have been collaborating with Argonne to develop the next generation of nuclear energy systems. For nearly four decades, nuclear power plants have supplied about one fifth of the nation’s electricity. Nuclear reactors make electricity by splitting atoms of uranium, and the fission reactions from this process create heat that is converted to reliable, abundant electricity. “Industries are very eager to collaborate with DOE national labs to rely on our unique expertise and address critical areas of needs in their reactor development programs.” — Dan O’Grady, Argonne nuclear engineer
“Industries are very eager to collaborate with DOE national labs to rely on our unique expertise and address critical areas of needs in their reactor development programs.” — Dan O’Grady, Argonne nuclear engineer
Together with nuclear industry partners, Argonne scientists are building on foundational knowledge to innovate a variety of new reactor concepts that are expected to be more flexible in site selection and scale and also less costly. These include reactors that could use recycled fuel, power remote communities or military bases and generate less waste than current reactors. These new power sources are also needed to meet the fast-paced energy needs that an artificial intelligence- and data-driven future demands.
X-energy’s Xe-100 reactors proposed in Texas will use a type of fuel called TRISO, which stands for tri-structural isotropic particle fuel. TRISO fuel is highly resistant to melting down in a high-temperature reactor, leading some to call it the most robust nuclear fuel on Earth.
The fuel is packed into billiard-ball-size “pebbles” that are fed into the reactor by the tens of thousands. Argonne scientists are providing detailed computational fluid dynamics simulations that describe all the pebbles in the reactor core, helping Maryland-based X-energy understand the fuel pebbles’ thermal efficiency and determine the reactor efficiency and safety under different conditions.
“We are modeling each individual pebble, which is a very high level of detail and challenging to simulate,” said Adrian Tentner, an Argonne scientist working on the project. He added that Argonne is also conducting two-phase flow modeling to understand the dynamics of water and vapor in the steam generator that will convert heat from the fuel pebbles into electricity.
Some other collaborations at Argonne explore ways to extract more power from used nuclear fuel, most of which has the potential to be recycled. With Wisconsin-based SHINE Technologies (From waste to watts: Unlocking the power in used nuclear fuel | Argonne National Laboratory), and California-based Oklo, Argonne is developing cost-effective, scalable methods to recover useful materials from used fuel. Support for multiple projects comes from both DOE’s Office of Technology Commercialization and the Advanced Research Projects Agency–Energy.
With Oklo, for example, Argonne is working on incorporating recent advances in four different steps to recycle fuel for the metal-fueled fast reactors that Oklo is designing.
“A lot of technology development focuses on one operation at a time, but there isn’t nearly as much focus on moving between the operations and making sure that they all work together,” said Krista Hawthorne, section manager for pyroprocess engineering at Argonne. “We’re working to demonstrate four of the key steps for recycling used fuel together at an engineering scale that is relevant to industrialization.”
In other work with Oklo, data from Argonne’s Mechanisms Engineering Test Loop facility and Thermal Hydraulic Experimental Test Article pool-type sodium facility helped Oklo validate reactor thermal hydraulic and safety analysis codes used in their license application to the U.S. Nuclear Regulatory Commission.
“Partnering with Argonne has been instrumental in accelerating our deployment,” said Jacob DeWitte, co-founder and CEO of Oklo. “Their expertise in fuel recycling, thermal hydraulics and safety analysis has helped validate our design and licensing approach. It’s not just about individual technical contributions — it’s about integrating those capabilities in a way that moves the whole system forward toward industrial deployment.”
Companies such as Pennsylvania-based Westinghouse also rely on Argonne’s suite of software and codes for analyzing safety and other aspects of new reactor designs. These tools include SAS4A/SASSYS-1 for safety and fuel performance analysis in liquid-metal-cooled nuclear reactors; DASSH for calculations that determine coolant flow and temperature distributions; and PyARC, which is used to analyze neutronics and fuel cycle characteristics of nuclear reactors.
Argonne’s pivotal role in nuclear science — it is often called the nation’s first national laboratory and was born of the Manhattan Project — has led to decades of partnership and collaboration. “Industries are very eager to collaborate with DOE national labs to rely on our unique expertise and address critical areas of needs in their reactor development programs,” said Dan O’Grady, Argonne nuclear engineer.
Argonne’s work benefits the U.S. nuclear industry at large. “All the methods are typically open source codes,” said Nicolas Stauff, group manager of nuclear applications and economics at Argonne. “Any development done here for one company is helping us further advance our capabilities, which will benefit the wider nuclear industry.”
Argonne also directly supports companies in designing reactor cores and optimizing their performance through workflow automation and multi-criteria optimization techniques using the WATTS platform. In work funded partly through DOE’s Office of Technology Commercialization, Westinghouse has collaborated with Argonne to use WATTS to develop optimal design solutions for advanced reactor concepts such as the company’s eVinci microreactor.
“Argonne’s advanced modeling capabilities and the WATTS platform have played an important role in supporting Westinghouse’s advanced reactor development programs,” said Fausto Franceschini, consulting engineer in the eVinci Fuel group at Westinghouse. “Their expertise in high-fidelity reactor analysis and design optimization has allowed us to accelerate our design process and confidently explore innovative solutions that align with our performance and safety goals.”
Other recent industry partnerships include ARC Clean Energy, Constellation Energy, Dominion Energy, Electric Power Research Institute, Exelon, Framatome, General Atomics, General Electric-Hitachi Nuclear Energy, HolosGen, Kairos Power, Moltex Energy, TerraPower, Terrestrial Energy and Westinghouse, among others. All of these partnerships seek to bring together the unique capabilities of private industry and the vast resources of a national laboratory to advance cutting-edge solutions to the nation’s nuclear energy needs.
(NW/NS)
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