Sam Altman, CEO of OpenAI, has stepped down as chairman of the board of Oklo, a California-based nuclear startup. This comes just months after Altman helped Oklo go public through a merger with AltC Acquisition Corp.

Oklo says its microreactors, called Aurora, have smaller and simpler designs that will range from 15 megawatts to as much as 100 megawatts or more.