X Energy and a unit of Southern Nuclear Operating Company (Southern Nuclear) have signed a memorandum of understanding for commercialising and deploying high-temperature gas-cooled reactor (HTGR), the Xe-100.
The Xe-100 reactor series will generate zero-emission energy for reliable electricity.
This collaboration intends to make available an additional nuclear solution that supports clean energy.
X Energy CEO Dr Kam Ghaffarian said: "We are thrilled to have Southern Nuclear involved with our project.
"I founded X-energy in 2009 out of a desire to make a significant and lasting contribution to clean energy generation in the US and around the world. This relationship firmly puts us on that path."
Earlier this year, the US Department of Energy (DOE) separately issued both X Energy and the Southern Company-TerraPower partnership with five-year Advanced Reactor Concept Cooperative Agreement awards.
The award for X Energy focuses on advancement of reactor design, fuel development; and initial licensing activities.
Southern Nuclear chairman, president and CEO Stephen Kuczynski said: "Our relationship with X Energy builds upon the DOE awards we each received and puts the industry on a strong path to providing clean and safe nuclear energy for generations to come.
"We understand fully the time and manpower it will take to bring the first advanced reactor to market and feel confident that pursuing this goal together will best leverage our combined research and commercial operation experience to do so."