Three Mile Island, the site of worst nuclear disaster in the United States, is reopening and will exclusively sell the power to Microsoft as the company searches for energy sources to fuel its AI ambitions. Constellation Energy announced Friday that its Unit 1 reactor, which closed five years ago, is expected to be revived in 2028, dependent on Nuclear Regulatory Commission approval. Microsoft will purchase the carbon-free energy produced from it to power its data centers to support artificial intelligence.