Pennsylvania’s dormant Three Mile Island nuclear plant would be brought back to life to feed the voracious energy needs of Microsoft under an unprecedented deal announced Friday in which the tech giant would buy 100 percent of its power for 20 years. The restart of Three Mile Island, the site of the worst nuclear accident in U.S. history, would mark a bold advance in the tech industry’s quest to find enough electric power to support its boom in artificial intelligence. The plant, which...