OpenAI CEO Sam Altman is stepping down as board chair of the Helion — the fusion startup he backs — amid reported talks between the two companies. The deal, which was reported by Axios , is in early stages, and it could guarantee OpenAI 12.5% of Helion’s production — five gigawatts by 2030 and 50 gigawatts by 2035. OpenAI partner Microsoft signed a similar deal with Helion in 2023 to buy power starting in 2028. If the figures in Axios’ report prove to be accurate, it suggests that Helion expects to be able to rapidly scale production of its fusion power plant. The startup has said that each of its reactors will generate 50 megawatts of electricity, meaning it will need to build and install 800 reactors by 2030 and an additional 7,200 by 2035.  Helion wouldn’t confirm if talks with OpenAI were underway. A spokesman told TechCrunch the company has not announced any new customer agreements beyond those it already has with Microsoft and Nucor.…