General Matter (GM) says it will use a novel, scalable, cost-competitive technology to address a ‘commercial bottleneck’ in the U.S. nuclear fuel cycle and that it will be shipping enriched uranium by the end of the decade.

GM was one of four companies selected in October of 2024 by the U.S. Department of Energy (DoE) to provide enrichment services to help establish a steady U.S. supply of high-assay low-enriched uranium (HALEU). According to information available at the time, the company was registered in California earlier in the year, with Scott Nolan named as its CEO. Nolan is a former SpaceX employee who is a partner at venture capital firm Founders Fund which was co-founded by billionaire investor Peter Thiel.

On the 14^th of April, the company announced itself on social media. It posted on X that “For the past year, General Matter has been incubated within Founders Fund, with a team from SpaceX, Tesla, Anduril, national labs, and the DOD. We are undertaking an engineering challenge which, if successful, will fundamentally improve the trajectory of our nation.”

Nolan said, “I spent over a year at Founders Fund searching for an American enrichment company to invest in, only to find there wasn’t one. So we built our own. General Matter is filling the US nuclear fuel gap. We are enriching uranium in America, and we will be shipping by the end of the decade”.

On the same day, Bloomberg reported that Peter Thiel is joining the board of GM. According to Bloomberg, the company has “built up a small operation in Los Angeles of roughly two dozen engineers, nuclear scientists and safety experts, pulling staff from national labs and the private sector.”

GM has not provided any details of its process for enriching uranium, but on the 2^nd of December last year, Nolan submitted a Letter of Intent to the U.S. Nuclear Regulatory Commission (NRC) in anticipation of a “forthcoming application for the necessary licenses to support the production and handling of High-Assay, Low-Enriched Uranium (HALEU)”.

The letter notes that “General Matter has been awarded an Indefinite Delivery/Indefinite Quantity (IDIQ) contract by the Department of Energy’s Office of Nuclear Energy (DOE-NE) under Solicitation No. 89243223RNE000031. This award specifically supports the DOE-NE’s strategic objectives of securing a domestic supply chain of HALEU to support the continued development of advanced reactors and to strengthen US leadership in nuclear technology. As a DOE-NE HALEU IDIQ awardee, General Matter’s anticipated scope of responsibility under future task orders includes the enrichment, storage, and transportation of HALEU. These operations are critical to meeting the growing demand for enriched uranium necessary to support both domestic and international markets, with an emphasis on maintaining safety and security standards.”

HALEU contains between five and 20 percent of fissile uranium-235 and will be required to meet the fuel needs of many of the advanced reactor designs that are currently being developed.

Information submitted to the NRC with the Letter of Intent is classed as ‘proprietary and confidential’, with the company saying, “Years of cumulative effort have gone into the work supporting this content, and given the innovative and differentiated insights generated by the work, others would need to expend great effort to duplicate the information. This information cannot be acquired elsewhere.”

General Matter

The U.S. Department of Energy (DoE) announced on April 23^rd that the Argonne National Laboratory (ANL) has successfully swapped out an aging cold trap in the sodium test loop called METL (Mechanisms Engineering Test Loop). The upgrade is the first of its kind in the U.S. in more than thirty years, according to the DoE. The exchange will help test components and operations for the sodium-cooled fast reactors currently being developed.

Sodium-cooled fast reactors use liquid sodium as a coolant instead of water. They operate at higher temperatures and lower pressures than current commercial nuclear reactors. They achieve high power density with low coolant volume and sustain the fission chain reaction with fast neutrons. They are currently used in several countries including the US, Russia, China, and India.

More than seven hundred and fifty gallons of reactor-grade sodium flow through METL, making it the “nation’s largest liquid metal test facility,” according to the DoE. METL may not hold that record for long, however. TerraPower is a sodium fast reactor developer with cost-shared funding under the Advanced Reactor Demonstration Program to build a grid-scale Natrium reactor. It is currently constructing a sodium test and fill facility in Kemmerer, Wyoming, which is constructed to hold four hundred thousand gallons of liquid sodium.

A cold trap like the one that was just replaced in METL is a critical component of liquid metal reactor designs. It is utilized to filter out oxide impurities present in the sodium coolant. If these impurities are not removed, they can cause accelerated corrosion of the systems and lower flow rates, degrading the reactor’s performance.

ANL replaced the component to meet specifications for future METL experiments. The facility uses welded construction techniques that the DoE says are “consistent with the maintenance of any advanced liquid metal reactor.” The replacement project builds U.S. experience in working with and replacing sodium loop components.

The sodium in the cold trap was frozen before the cold trap was removed from the system and a new one was welded onto the sodium piping in its place. After months of planning, the process was accomplished in two weeks. During the replacement process, the rest of the sodium in the test loop remained molten and in operation, according to the DoE.

Matthew Weathered is a principal nuclear engineer at ANL. “It’s exciting. The METL team is revitalizing and developing these key operations and maintenance techniques to ensure we are able to deploy U.S. sodium cooled reactors in the near future.”

METL was developed in 2018 to help advance research on liquid metal technologies and to test components for potential use in sodium fast reactors. The facility can reach an operating temperature of six hundred and fifty degree Fahrenheit. This is within the typical sodium reactor temperature range.

Reactor developers who are working with Argonne’s team at METL include ARC Clean Energy, Oklo, and TerraPower. METL plans to expand its testing capabilities in 2026 with the installation fifth test vessel.

The cold trap replacement project was funded through the DoE’s National Reactor Innovation Center (NRIC), which funds operations and maintenance activities at the METL facility. ANL consulted with the French Alternative Energies and Atomic Energy Commission before performing the replacement operation.

Argonne National Laboratory