Nuclear innovator X-energy has secured a $700 million Series D round. Less than a year ago, the company expanded its Series C from $500 million to $700 million. With this latest injection, X-energy has raised $1.4 billion in roughly a year and $1.8 billion overall.
The fresh capital strengthens the company’s push to build a full supply chain for its small modular reactors (SMRs). Demand is already substantial. X-energy has logged orders for 144 SMRs, representing 11 gigawatts of future electricity generation. Its customer list includes Amazon, chemical giant Dow, and British energy firm Centrica. These are clear signs that industrial leaders see nuclear as a credible path to clean, reliable power.
Jane Street led the Series D after also participating in the expanded Series C. The round drew a deep bench of backers, including Ares Management funds, ARK Invest, Emerson Collective, Galvanize, NGP, Point72, Reaves Asset Management, Corner Capital, Segra Capital Management, Hood River Capital Management, and XTX Ventures.
Inside the Xe-100: Pebble-based power with high heat
Dr. Kam Ghaffarian founded X-energy in 2009 to reinvent nuclear energy and fulfil the growing energy needs of future generations while protecting our planet
X-energy’s flagship design, the Xe-100, is a high-temperature, gas-cooled reactor, a technology already proven in recent projects in Japan and China. Each reactor delivers 80 megawatts of electricity, using carbon-coated, billiard-ball-sized pebbles packed with uranium particles as fuel.
Instead of water, helium gas flows over the hot pebbles inside the reactor core, absorbing heat. That heat is then transferred to a steam turbine to generate electricity. The architecture allows the system to reach higher temperatures than conventional reactors, making it suitable not only for power production but also for industrial heat applications where emissions remain difficult to reduce.
This design has drawn increasing interest as companies seek stable, round-the-clock energy sources to support electrification, heavy manufacturing, and the explosive growth of data centres.
Tech giants push nuclear forward
One of the strongest signals of momentum comes from Amazon. Its Climate Pledge Fund led the first part of X-energy’s Series C, and the company has since committed to buying more than 600 megawatts of nuclear capacity in the Pacific Northwest and Virginia. Those reactors are expected to come online in the early 2030s. If all options under the partnership are executed, Amazon could deploy up to 5 gigawatts of X-energy capacity by 2039.
X-energy is competing in a crowded but high-stakes field of SMR developers aiming to revive the U.S. nuclear industry. Although optimism is rising, only a few SMR plants have been built globally and none yet in the United States. With its massive funding haul and growing industrial demand, X-energy is positioning itself to change that trajectory.
