SAN FRANCISCO :Helion Energy, a startup backed by OpenAI's Sam Altman and SoftBank's venture capital arm, has started construction on a site for a planned nuclear fusion power plant that will supply power to Microsoft data centers by 2028, the company said on Wednesday. The site in Malaga, Washington, is in the center of the state along the Columbia River, where Helion hopes to take advantage of grid infrastructure in place for the nearby Rock Island Dam hydroelectric plant. The startup still