Amazon, Constellation partner for Calvert Cliffs uprate

In the latest update to the ever-deepening connection between Big Tech and the nuclear industry, Constellation announced yesterday that it has entered into a long-term power purchase agreement (PPA) with Amazon.

This PPA will see Amazon supporting a 190-MWe uprate at the Calvert Cliffs nuclear power plant in Lusby, Md.

The details of the deal: Calvert Cliffs has two pressurized water reactors; its first unit entered commercial operation in 1975, and its second opened in 1977. The plant's net capacity is 1,788 MWe. Amazon's planed uprate would represent an increase of about 10 percent to the plant's overall capacity.

Uprate projects are generally categorized into three groups and are most easily delineated by the amount of capacity increase they involve. The size of the Calvert Cliffs uprate firmly places it in the largest group, an extended power uprate. As the Nuclear Regulatory Commission explains, these uprates generally "require significant modifications to major balance-of-plant equipment such as the high pressure turbines, condensate pumps and motors, main generators, and/or transformers."

That description lines up well with Constellation's announcement, which explains that, beyond the PPA, this deal will involve "more than $3 billion in Maryland infrastructure investment, including state-of-the-art improvements across the entire [plant]."

Beyond increasing capacity, Constellation said, the revenue certainty provided by Amazon will help in the utility's relicensing efforts for the plant. The licenses for both units at the site were renewed in 2000 and are set to expire in 2034 and 2036, respectively, unless Constellation pursues subsequent license renewal.

Constellation further stated that this revenue certainty will allow it to "make progress toward the development of new clean energy power plants at the site," though further specifics on those plans were not detailed.

What's in it for Amazon? "All the electricity generated by Calvert Cliffs will continue flowing to the PJM regional grid just as it does now," Constellation clarified in its announcement. The purpose of this PPA is not to facilitate a data center project co-located with the nuclear plant.

That distinction was worth emphasizing, considering that only a few months ago Amazon was planning to build a data center campus around Calvert Cliffs; that project was abandoned in August. Amazon did not explicitly acknowledge its reason for terminating that plan, but local opposition was notably strong. That same month, Calvert County enacted a six-month moratorium on new data center project applications or approvals.

This new PPA will still involve "690 megawatts of power, including the 190 megawatt uprate." That power will go through the PJM grid to Amazon facilities in the region, helping the company "manage its energy costs."

Amazon x Nuclear: While this is Amazon's first uprate deal, it's far from the company's first foray into nuclear. In 2024, the company announced two new partnerships, one with X-energy and one with Dominion Energy, to deploy a total of 5 gigawatts of nuclear by 2039. With Dominion, Amazon planned to deploy a small reactor in Virginia, though updates on this project have been sparse.

With X-energy, Amazon planned to deploy a 320-MWe project in Washington state in partnership with Energy Northwest. Updates have been more regular on this project, dubbed the Cascade Advanced Energy Facility.

The company also has a more complex partnership with Talen Energy. In 2024, Amazon bought a 960-MWe data center campus from Talen, which was co-located with and directly connected to the Susquehanna nuclear power plant. This deal was complicated by key objections from the Federal Energy Regulatory Commission, which was concerned with the community impact of behind-the-meter power sales. In the end, Talen and Amazon still expanded their nuclear partnership in 2025.

Other players: Amazon is not the only major Big Tech player in the nuclear space; several other power-hungry companies are investing in nuclear on multiple fronts. Google is involved with uprates for Southern Nuclear's Vogtle and Hatch, the restart of NextEra Energy's Duane Arnold, Kairos Power's Hermes 2 reactor, nuclear start-up Elementl Power, and a PPA with Finland's Loviisa plant. Meta has made deals with Vistra, Oklo, and TerraPower, along with a PPA deal for Constellation's Clinton. Microsoft is investing in the restart of Constellation's Crane (the former Three Mile Island-1).