How Much More Electricity Can Nuclear Power Plants Provide?

Constellation, the largest nuclear operator in the US, has announced plans to add nearly a gigawatt of new capacity across 11 existing nuclear reactors at six plants. The move is part of a broader push to use power uprates, or equipment upgrades that allow existing reactors to produce more electricity, to meet rising power demand tied to AI and data centers.

Background: Uprates Return as Demand Rises

A power uprate can be minor, involving changes to instrument setpoints or plant calculations. More major overhauls can boost reactor power by as much as 20%, but they require replacing plant equipment.

In a major uprate, operators generally use fuel that is more highly enriched, or a higher volume of fresh fuel, in the reactor. That produces more steam, which turns a turbine and generates electricity. The main turbines and equipment such as pumps, motors, generators, and transformers are upgraded to handle the additional energy.

US operators have been doing power uprates since the 1970s. But they became less common in recent years as electricity demand plateaued and cheap natural gas put financial pressure on nuclear plants. Some plants closed, and adding capital to produce more electricity did not make much sense at others. Between 2001 and 2010, the Nuclear Regulatory Commission approved over 80 uprates. Between 2011 and 2020, the number was 33.

The most recent major uprate approved in the US was for three reactors at the Browns Ferry nuclear power plant in Alabama. A $475 million project expanded that plant's power capacity by 14% between 2018 and 2019.

Development Process: AI Demand Changes the Equation

The rise of AI and the related boom in electricity demand changed the calculus. Operators are again looking to squeeze more output from existing plants, and shuttered plants like Palisades and Three Mile Island are racing to reopen.

Pushing existing reactors to produce more could help provide more clean power for data centers, quickly. On a per-kilowatt basis, the Constellation project is less expensive than building a new reactor, but it is still more expensive than building a new utility-scale solar farm with energy storage or a combined-cycle natural-gas plant.

Even at that higher cost, uprates are in high demand. The US nuclear fleet currently has roughly 98 gigawatts of total power capacity. Depending on who you ask, there are somewhere between three and eight additional gigawatts on the table from uprates. A significant share of that potential is already reflected in regulatory expectations: the Nuclear Regulatory Commission already expects applications to add 2.4 gigawatts of power to reactors through 2032.

Latest Progress: Constellation, Vistra, and Long-Term Tech Contracts

Constellation announced plans to spend more than $4.3 billion on uprates to 11 reactors. The additional electricity will be enough to power roughly 700,000 US homes.

Behind the financing is Big Tech money. Google agreed to buy electricity from these plants, and the 20-year agreement was a major factor in making the uprates happen. As Joe Dominguez, Constellation's CEO, told the New York Times: "These are capital intensive, labor intensive projects that require a different price point than the market trades at, frankly."

Also in recent weeks, the Department of Energy awarded a $4.2 billion loan to Vistra for previously announced upgrades at three plants. The Department of Energy also shared that it will commit over $4 billion to help finance upgrades and modernization for Vistra nuclear power plants across Pennsylvania and Ohio. Those projects will add 433 megawatts of power capacity, and Meta has already signed on to buy electricity from the plants in a long-term deal.

Current Stage: A Fraction of the Needed Power

The scale of the demand is still larger than the near-term nuclear uprate pipeline. PJM, the grid operator that covers much of the East Coast, expects about 30 gigawatts of additional peak demand because of AI by 2030. All possible nationwide nuclear uprates would cover just a fraction of that.

Making the most of existing nuclear reactors is a relatively easy win at a time when zero-emissions power is in high demand. But the current wave of uprates, financing, and long-term purchases shows that the next constraint is not only equipment or contracts. If more nuclear power is needed to meet future demand, eventually that will require building new reactors.

The account comes from The Spark, MIT Technology Review's weekly climate newsletter, which is sent every Wednesday.

Meta description: Constellation plans nuclear uprates adding nearly a gigawatt for AI data centers, while Department of Energy financing supports Vistra upgrades in Pennsylvania.

Tags: nuclear power, Constellation, AI data centers, power uprate, Vistra

Featured image: A stylized turbine and glowing grid lines, abstract technology style, no real people, no company logos, no text.