"TerraPower starts construction of Natrium reactor in Wyoming." "The project features a 345MW sodium-cooled fast reactor with a molten salt-based energy storage system, which can boost the system's output to 500MW of power when needed. According to TerraPower, the storage component allows the plant to integrate seamlessly with renewable resources."
"TerraPower Chairman and Founder, Bill Gates," -- wait, that Bill Gates? Apparently so -- "commented at the groundbreaking ceremony: 'I believe that TerraPower's next-generation nuclear energy will power the future of our nation -- and the world."
So the idea is the reactor is a "breeder" reactor where neutrons from fission "breed" more fissile material, in this case plutonium-239 (from depleted uranium). Liquid sodium is used as the coolant, which transfers the heat to molten salt. The molten salt tanks are used to generate steam, and the amount of steam generated can be cranked up or down to match electricity demand on a moment-by-moment basis. It is at this point where the "integrate seamlessly with renewable resources" objective is accomplished.
TerraPower starts construction of Natrium reactor in Wyoming