Nuclear technology company X-Energy announced that it has raised $700 million in a Series C-1 financing round, with proceeds aimed at accelerating the development of the company’s small modular nuclear reactor technology.

The announcement represents an upsizing of the funding round, following an initial $500 million capital raise announced in October 2024, led by Amazon’s Climate Pledge Fund, alongside an agreement with Amazon to bring more than 5 GW of projects online across the U.S. by 2039.

Kam Ghaffarian, Ph.D., Founder and Executive Chairman of X-energy, said:

“We are proud to have gained the additional support from our industry, government, and investment community since X-energy was founded more than 15 years ago. We look forward to continuing to advance and scale our technology and realize our vision of fulfilling the growing energy needs of future generations.”

Founded in 2009, Rockville, Maryland-based X-Energy is a developer of nuclear reactor and fuel technology. The company’s TRISO-X fuel seals uranium particles in a protective coating, which can withstand high temperatures without melting, making it highly resistant to fuel failure and release of radioactive materials, eliminating the need for massive containment facilities. The company’s SMR reactor, Xe-100 is a high-temperature gas-cooled reactor operates at temperatures higher than 750°C, and contains more than 200,000 TRISO-X-based fuel pebbles, which are gravity-fed in continuous rotation through the core, allowing the reactor to run without fuel interruption for 60 years. Helium is circulated through the core, absorbing immense heat, and is used to boil water into steam to turn a turbine for the production of carbon-free energy.

The company that said it would use the funds to support the completion of its reactor design and licensing as well as the first phase of its TRISO-X fuel fabrication facility in Oak Ridge, Tennessee. The funding will also support future carbon-free projects that will use X- energy’s Xe-100 advanced small modular nuclear reactors (SMRs).

New investors joining the round include Segra Capital Management, Jane Street, Ares Management funds, Emerson Collective, and others, the company said.

Ghaffarian added:

“We welcome our new investors along our journey to accelerate the development and deployment of advanced nuclear energy and meet the growing demand for reliable, safe and clean energy.”