Last Energy, an advanced nuclear technology company, said it has closed an oversubscribed Series C financing of more than $100 million to fund development of its pilot reactor and prepare for initial deployments of its micro modular nuclear plants.
The round was led by the Astera Institute, with participation from JAM Fund, Gigafund, The Haskell Company, AE Ventures, Ultranative, Galaxy Interactive, and Woori Technology Co., Ltd., among other investors. The company said the financing is intended to support its U.S. Department of Energy pilot efforts and help move its reactor platform toward commercialization.
Last Energy said it is prioritizing completion of its PWR-5 pilot reactor while advancing commercialization of its PWR-20 product. The company also said it plans to expand its footprint in Texas through additional investment in manufacturing capabilities and deeper engagement with partners, aligning with its strategy to build factory-fabricated nuclear plants designed for repeatable deployment.
On the regulatory and project development front, the company said it is pursuing pathways in both the United States and the United Kingdom. Last Energy said it was selected in August 2025 for the DOE Reactor Pilot Program, used a previously procured full-core load of fuel to secure a lease at the Texas A&M RELLIS Campus, and signed what it described as the first known Other Transaction Agreement between the DOE and a reactor developer. The company said these steps are in preparation for an anticipated 2026 criticality demonstration. In the UK, Last Energy said it has completed a Preliminary Design Review and described itself as the only known company with a regulator-confirmed pathway toward a potential 2027 site license decision, supported by its recognition in the Atlantic Partnership for Advanced Nuclear Energy.
Last Energy’s approach centers on a fully integrated, hermetic steel containment built around pressurized water reactor technology and off-the-shelf fuel. The company said it is productizing the nuclear steam supply system into a supply chain-ready design that can be factory-manufacturable, aiming to shorten timelines and improve scalability compared with traditional site-built nuclear construction. The company also said this model has helped it build one of the industry’s largest commercial microreactor pipelines, with interest in both electricity and heat only use cases, including from data center and industrial customers, and with plans to deploy 20 MWe microreactors in clusters near AI data centers and industrial facilities.
The company noted that its announcement includes forward looking statements and that actual results could differ materially due to a range of business, market, political, legal, development, competitive, and manufacturing related risks.
KEY QUOTES:
“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.”
Bret Kugelmass, Founder And CEO, Last Energy
“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,” said Jed McCaleb, Co-Founder of the Astera Institute. “We’re proud to support their work because this early, high-conviction approach can unlock new opportunity spaces in energy.”
Jed McCaleb, Co-Founder, The Astera Institute
“Ensuring steady access to clean power is critical to enabling the next wave of industrial and economic growth,” said Sam Englebardt, GP at Galaxy Interactive, a venture platform within Galaxy Digital Inc. (NASDAQ: GLXY). “We believe Last Energy is well-positioned to deliver on this moment with a pragmatic yet revolutionary solution to nuclear deployment, built around one of the most capital-efficient approaches we’ve seen. Their micro-modular reactors aim to offer a pathway to providing meaningful new energy capacity in the settings that need it most.”
Sam Englebardt, GP, Galaxy Interactive
