Last Energy, an advanced nuclear technology company, has announced that it has closed an oversubscribed Series C of more than $100 million led by the Astera Institute, with participation from JAM Fund, Gigafund, The Haskell Company, AE Ventures, Ultranative, Galaxy Interactive Fund and Woori Technology Co., Ltd., among others.
Last Energy is operating at the forefront of new nuclear deployment, advancing projects through both U.S. and UK regulatory pathways. In August 2025, the company was selected for the DOE’s Reactor Pilot Program. Leveraging a previously procured full core load of fuel, the company secured a lease at the Texas A&M–RELLIS Campus and signed the first developer Other Transaction Agreement (OTA) with the Department in preparation for an anticipated July 2026 criticality demonstration.
“We believe this financing will fully capitalize us through our DOE pilot project and position us to transition into commercialization of our production power plants,” said Bret Kugelmass, Founder and CEO of Last Energy. “A new nuclear era is underway, and we intend to showcase how factory fabrication will unlock the scalability that the energy market demands.”
In the United Kingdom, Last Energy is the only developer to complete a Preliminary Design Review and the only company with a regulator-confirmed pathway toward a potential 2027 site license decision, further supported by its recognition in the Atlantic Partnership for Advanced Nuclear Energy.
“This financing fully capitalizes our DOE pilot project and positions us to transition swiftly into commercialization of our production power plants,” said Bret Kugelmass, Last Energy Founder and CEO. “A new nuclear era is underway, and we intend to showcase how factory fabrication will unlock the scalability that the energy market demands.”
Last Energy will now focus on completing its PWR-5 pilot reactor, advancing the commercialization of its planned PWR-20 production version, and strengthening its footprint in Texas through expanded investment in manufacturing capabilities and partner engagement.
“Astera exists to support ambitious teams exploring ideas with transformative potential. Last Energy is applying a product mindset to nuclear energy that could reshape power generation,” Astera Institute Co-Founder Jed McCaleb, said. “We’re proud to support their work because this early, high-conviction approach can unlock new opportunity spaces in energy.”
By significantly reducing the time and cost of deployment, Last Energy looks to decarbonize global energy production, increase access to 24/7 baseload power and create a scalable clean energy future.
At the core of Last Energy’s approach is a fully integrated, hermetic steel containment built around proven pressurized water technology and off-the-shelf fuel, transforming its nuclear steam supply system into a supply-chain-ready, factory-manufacturable product. This productized approach has driven one of the industry’s largest commercial microreactor pipelines, with traction in both electric and heat-only applications with data center and industrial customers, positioning the company to scale its technology globally.
