Constellation Energy has a customer for the Calvert Cliffs uprate. Amazon signed a 20-year agreement for 690 megawatts from the Maryland nuclear plant, including 190 MW of new capacity, and Constellation says the deal supports about $3 billion of investment at the site. The companies announced the agreement Sept. 30.
What Constellation hasn’t said is who will do the work, or what the work is.
What the $3 Billion Covers
The release describes plant-wide improvements, the added capacity, relicensing for another 20 years and possible future generation at the site. It doesn’t split the $3 billion among them. ENR reported that the company hasn’t identified major equipment modifications or any engineering or construction contractor, and that Constellation didn’t immediately respond to its questions.
So resist the easy arithmetic. Dividing $3 billion by 190 MW gives close to $15,800 a kilowatt, which would be absurd for an uprate. The figure plainly includes life-extension work on a 1,790 MW station whose two units are licensed only through July 2034 and August 2036.
The new output is due between 2030 and 2032. That’s a refueling-outage schedule. Heavy work on a running reactor gets done in windows of a few weeks per unit.
Calvert Cliffs Uprate History and the NRC Path
This plant has been here before. It was the first in the U.S. approved for a power uprate, a 5.5% stretch in 1977, and it took a second, 1.4% increase in 2009 by installing more precise feedwater flow instruments. A 190 MW gain is about 10.6% of current capacity. That’s a different class of project. Constellation said last November it would require new equipment and technology, without listing any.
NRC staff met with Constellation behind closed doors on Oct. 1 about upcoming license amendment requests for both units, according to ENR. The agency didn’t say whether those involve the uprate. A spokesman told the magazine a review schedule comes only after an application is filed and accepted.
Relicensing has its own clock. Under exemptions granted in November 2024, Constellation must file by July 31, 2031, for Unit 1 and Aug. 13, 2033, for Unit 2 to keep the existing licenses in force during review.
Who Builds Nuclear Uprate Work
No contractor is named, but the spending pattern is visible. In February 2025 Constellation announced about $100 million of electrical and equipment upgrades at Calvert Cliffs, covering pumps, motors, valves, control-rod systems and a 13-kV transformer overhaul, plus $68 million for 24 substation breakers. This year’s Unit 1 outage carried nearly $90 million of upgrades, including a 151-ton, $4.8 million transformer, ENR reported.
That’s roughly $260 million disclosed in pieces before Amazon signed anything. The rest will likely arrive the same way: outage by outage, package by package, through the specialty nuclear contractors and equipment makers that already hold site access.
Bechtel built the original plant, by Constellation’s account, and held the EPC contract with Areva for a third reactor that died in 2010 in a dispute over a federal loan guarantee fee. Its nuclear group has had a rough month elsewhere, having left the Natrium project.
Constellation is also the owner restarting Three Mile Island Unit 1 as the Crane Clean Energy Center, so it has a recent template for buying this kind of work. The contrast with new build is plain: TVA’s Clinch River small modular reactor got its construction permit this week with no start date. Calvert Cliffs’ reactors are already running.
The dates to track are regulatory. Until an uprate amendment lands on the NRC docket, 2030 is a target with a customer attached and no public application behind it.
