Building nuclear power plants takes a long time, so some companies are looking to upgrade older reactors to squeeze even more power out of them instead. These types of upgrades can cost billions and require approval by regulators, but they can often be completed in five years or less at a fraction of the cost of building a new plant from scratch. Many tech giants are eager to pay for these upgrades to power AI. Increasing production from existing nuclear plants will add an estimated 6,000 to 8,000 megawatts of electric capacity to US grids.