Billionaire Bill Gates' advanced nuclear reactor company TerraPower LLC and PacifiCorp have selected Wyoming to launch the first Natrium reactor project on the site of a retiring coal plant, the state's governor said on Wednesday.

TerraPower, founded by Gates about 15 years ago, and power company PacifiCorp, owned by Warren Buffet's Berkshire Hathaway, said the exact site of the Natrium reactor demonstration plant is expected to be announced by the end of the year.Small advanced reactors, which run on different fuels than traditional reactors, are regarded by some as a critical carbon-free technology than can supplement intermittent power sources like wind and solar as states strive to cut emissions that cause climate change.