Company hails federal partnership deigned to bring advanced nuclear to market
US-based reactor and fuel developer X-energy has signed an agreement with the US Department of Defense’s (DoD) defence innovation unit and the US Department of the Air Force to advance development of its Xenith high-temperature gas-cooled microreactor, the company said.
X-energy said the agreement is part of the Advanced Nuclear Power for Installations (ANPI) programme, which aims to speed up deployment of microreactors to provide power at military installations.
The programme allows governmental sponsors such as the Air Force to use flexible contracting for faster development and deployment of commercial nuclear systems.
According to X-energy, the deal aligns with an executive order issued by US president Donald Trump in May 2025 directing the DoD to deploy an advanced reactor at a military site before the end of the decade.
X-energy said Xenith was first developed for the DoD’s project Pele mobile microreactor initiative and has been selected for an “enhanced engineering phase”.
Xenith is a factory-built high-temperature gas-cooled microreactor designed to deliver between 3 MW and 10 MW of electric output, with the option to supply high-temperature process heat. Capable of operating for up to 20 years without refuelling, the system is intended for deployment in months rather than years, making it suitable for military, industrial and remote applications.
X-energy has begun pre-application engagement with the US Nuclear Regulatory Commission, submitting design criteria, analytical methods and operational concepts as part of efforts to licence the reactor for both defence and commercial use.
J. Clay Sell, X-energy’s chief executive, said the agreement reflected “the full force of federal partnership mobilised to bring advanced nuclear to market”.
X-energy is also developing the Xe-100 high-temperature gas-cooled reactor for grid-scale applications.
In 2020, X-energy was selected by the US Department of Defence to develop, licence and build an operational Xe-100 advanced SMR and Triso-X (tristructural isotropic) fuel fabrication facility to power the new plant.
