X-energy is a private American nuclear reactor and fuel design engineering company.

It is developing a Generation IV high-temperature gas-cooled pebble-bed nuclear reactor design.

[2][3][4] In 2019, X-energy received funding from the United States Department of Defense to develop small military reactors for use at forward bases.

[9] In December 2022, X-energy planned to go public in a $2 billion deal using the special-purpose acquisition company Ares Acquisition, but this was called off in October 2023 due to the then macroeconomic situation and the effect on the market of the cancellation of the first U.S. SMR deployment project, the Carbon Free Power Project, because of cost increases.

[7] X-energy claims that TRISO fuel will make nuclear meltdowns virtually impossible.