The South Bay region of Los Angeles is becoming a hotspot for innovation in the nuclear power sector. Three companies from the area—Antares Nuclear, Valar Atomics, and Radiant Industries—have been selected for the U.S. Department of Energy’s reactor pilot program. Two of the firms are headquartered in El Segundo, with the third, Antares Nuclear, located just twelve miles away in Torrance. The companies are part of a national effort to accelerate the development of advanced nuclear technologies, and their success so far suggests the South Bay could become a major center for next-generation reactor development.
The Department of Energy launched its reactor pilot program in June 2023 to support the development of small modular reactors (SMRs) and attract private investment. The initiative aims to speed up the regulatory process and help companies move their technologies toward commercial viability. The program has proven successful for the South Bay companies. Each has secured funding rounds exceeding $300 million since joining the initiative, bringing their total capital to around $600 million. Antares Nuclear and Valar Atomics reached a major technical milestone in the program: achieving criticality before a July 4 deadline set by the Trump administration. This accomplishment marked a key step in validating their reactor designs.
Reaching critical milestones
Criticality in nuclear reactor development refers to the point at which a self-sustaining chain reaction is established. It is not the same as generating power but is an essential proof of concept. Antares Nuclear was the first among the three South Bay companies to achieve criticality. Their reactor reached this stage on June 4 at the Idaho National Laboratory in Idaho Falls. Two weeks later, Valar Atomics also succeeded, meeting the target set by the Trump administration. Both companies surpassed the program’s key deadline, which was intended to push reactor developers toward faster progress in the field.
Radiant Industries is not far behind. The company aims to achieve criticality by the end of this year, following its own development timeline. Stephen Cheung, the CEO of the Los Angeles County Economic Development Corp., described the progress as a promising signal that the region is building a strong foundation for a new nuclear technology cluster.
Smaller, smarter reactors
A defining feature of all three companies is their focus on small, compact reactors. Each reactor is designed to fit within a container roughly the size of a minibus and can be transported directly from a factory to an installation site. Instead of traditional fuel rods that can reach lengths of up to 14 feet, these next-generation reactors use tiny ceramic-coated fuel pellets. These poppy-seed-sized units are embedded in heat-resistant graphite structures. This design is a major departure from older nuclear technologies, which require large-scale infrastructure and complex handling.
Nana Menya Ayensu, a senior fellow at the Atlantic Council, said the shift toward smaller reactors aligns with current investment trends. Large nuclear projects often come with billions in costs—far beyond what most venture capital firms are willing to finance. Smaller reactors, however, allow for modular manufacturing and the benefits of scale. Each new batch can be produced more efficiently than the last, cutting costs and making nuclear power more viable for a range of applications. Ayensu highlighted that these reactors are particularly well-suited for niche markets, such as military bases, remote communities, and even space exploration missions.
Waste, scale, and future goals
While the companies have made significant progress in reactor design and funding, they are honest about the challenges ahead—especially in managing nuclear waste. The microreactors simplify short-term waste storage by reducing the amount of material produced compared to traditional reactors. However, the long-term solution remains an open question. The U.S. has yet to establish a permanent nuclear waste repository, a problem that has lingered for more than 30 years. None of the companies have proposed a definitive answer for this ongoing issue.
Despite this, all three startups are focused on scaling their operations through modular production. The plan is to manufacture hundreds, and eventually thousands, of microreactors. This approach could help reduce costs significantly and make nuclear power more accessible to a wider range of users. Antares Nuclear, for example, is already targeting military and space applications for its Mark-0 reactor. Valar Atomics and Radiant Industries have similar ambitions but have not yet outlined specific deployment strategies. The emphasis on modular design and repetition is key to driving down expenses and expanding the reach of these new nuclear technologies.
Antares Nuclear was founded in 2023 by Jordan Bramble, a former engineering executive at Northrop Grumman, and Julia DeWahl, a former director at Space Exploration Technologies. The company has raised approximately $600 million to date, including a recent $470 million Series C round led by Paradigm Capital and Caffeinated Capital Management. This level of backing signals strong investor confidence in the company’s vision for the future of nuclear power. As more companies in the South Bay follow suit, the region may well become a defining hub for a new era of nuclear innovation.