Nuclear plant upgrades offer limited relief for rising power demand

US nuclear operators are turning to upgrades at existing plants as AI data centers drive electricity demand higher. Constellation plans to add nearly a gigawatt of capacity across 11 existing nuclear reactors at six plants. Vistra’s planned upgrades in Pennsylvania and Ohio will add 433 megawatts of power capacity, supported by Department of Energy financing.

Known as power uprates, these projects range from adjustments to plant settings to major equipment replacements that can boost reactor power by as much as 20%. Larger upgrades typically involve more highly enriched fuel or a higher volume of fresh fuel, alongside improvements to turbines, pumps, generators and other equipment.

Technology companies’ purchasing commitments are helping make the investments viable. Google’s 20-year agreement to buy electricity from Constellation plants was a major factor behind those upgrades, while Meta has signed a long-term deal for electricity from Vistra plants. Constellation’s project costs less per kilowatt than a new reactor, but more than new utility-scale solar with storage or a combined-cycle natural-gas plant.

The potential remains limited. The US nuclear fleet has roughly 98 gigawatts of capacity, with somewhere between three and eight additional gigawatts available through uprates. By comparison, East Coast grid operator PJM expects about 30 gigawatts of additional peak demand because of AI by 2030. Meeting substantially more demand with nuclear power would eventually require new reactors.