Austin-based Last Energy has snapped up $100 million in Series C funding led by the Astera Institute, with participation from AE Ventures, Galaxy Fund, Gigafund, JAM Fund, Woori Technology, and others. The round places the company among a fast-growing group of nuclear startups drawing investor interest as power demand accelerates, particularly from data centres and advanced computing infrastructure.
The investment will help the company commercialise its small nuclear reactor technology, as demand for power to run artificial intelligence systems drives renewed interest in nuclear energy.
Using proven reactor designs to reduce risk
Last Energy was founded by Bret Kugelmass, who also founded the Energy Impact Center, from which Last Energy spun out in 2019 to develop scalable, small modular nuclear reactors (SMRs). It is developing small modular reactors capable of producing 20 megawatts of electricity, enough to power around 15,000 homes. Instead of custom-built mega projects, Last Energy’s reactors are designed for repeatable manufacturing, using standardised processes and components to reduce cost and construction time.
Its reactor design is based on a pressurised water reactor developed decades ago by the US government for the NS Savannah, the world’s first nuclear-powered merchant ship. While that system was much smaller, its performance and safety characteristics were well documented.
It has modernised the design to reach a 20-megawatt output while keeping the underlying architecture familiar to regulators and engineers. The company also relies heavily on off-the-shelf components for common systems, a move intended to lower production costs and avoid complex, bespoke supply chains.
Before reaching commercial scale, the company will deploy a 5-megawatt pilot reactor at a site leased from Texas A&M. The newly raised funding fully covers this project, which is expected to come online next year. Commercial-scale reactors are targeted for production in 2028.
Sealed reactors and simplified decommissioning
A key feature of Last Energy’s approach is its sealed reactor design. Each reactor core is permanently encased in around 1,000 tons of steel and is not serviced during its operational life. The steel enclosure provides shielding and structural protection, with the metal itself costing an estimated $1 million per unit.
Reactors arrive on site pre-fueled with six years’ worth of uranium. Heat generated inside the core warms the steel casing, while water flowing through external pipes captures that heat to generate electricity. With no penetrations beyond electrical and control connections, the system is designed to minimise complexity and risk.
When the reactor reaches the end of its life, it remains on site. The steel casing doubles as a long-term waste container, removing the need for separate disposal. Combined with manufacturing efficiencies, Last Energy believes this model could steadily drive down nuclear power costs as production volumes increase.
What’s next?
Last Energy is taking a different approach to expanding nuclear power, focusing on smaller reactors that can be built faster, deployed flexibly, and scaled at a lower cost. As global electricity demand rises, particularly from data-heavy infrastructure, the company is positioning itself as a practical answer to a growing problem.
Chief Executive Officer Bret Kugelmass said in the statement: “This financing fully capitalises our DOE pilot project and positions us to transition swiftly into commercialisation of our production power plants.”
