Three Mile Island restart project 'ahead of schedule'

Friday, 28 February 2025

Last September, Constellation signed a 20-year power purchase agreement with Microsoft to restart Three Mile Island Unit 1 as the Crane Clean Energy Center: the 837 Mwe pressurised water reactor had been retired for economic reasons in 2019.

Since then, more than 200 full-time employees have been hired for a variety of jobs, with dozens more recruited to fill key roles in the coming weeks, Constellation said in an update released last week. Work has begun to train and license reactor operators and senior reactor operators. The main office building has been fully restored and enhancements to the training centre and control room simulator are nearly complete.

Thousands of inspections and equipment upgrades are needed to ensure a safe and efficient restart, and these are also progressing on schedule, the company said. Rigorous inspections of the plant’s steam generator, main generator, rotor, turbines, feedwater heaters and condensers have been carried out. A contract for the construction of three new main power transformers - one of the largest new equipment purchases required for the restart - has been awarded and a further USD35 million invested to ensure they reach the station in 2026.

A turbine blade at the Crane Clean Energy Center undergoes inspection (Image: Constellation)

Constellation has filed an interconnection request with regional transmission operator PJM to allow Crane's power to be added to the grid. It is also on track to file all the required licensing and regulatory documents with the Nuclear Regulatory Commission (NRC), which has the ultimate authority to approve the restart. The regulator held its first public meeting about Crane in late October, and Constellation submitted its initial restart plan on 4 November. A second NRC public meeting to provide an overview of Cosntellation's emergency plan for the site was held on 19 February. All of Constellation’s regulatory filings for the Crane Clean Energy Center are available from the NRC.

"Every new milestone confirms our belief that the Crane Clean Energy Center can be returned to service better than ever, restoring 835 megawatts of carbon-free energy to the regional grid at a critical time for Pennsylvania and our nation," Constellation President and CEO Joe Dominguez said. "Major maintenance and upgrades are proceeding ahead of plan, new equipment has been ordered, and we are making tremendous progress on hiring and training the next generation of skilled workers to operate the plant at world class levels of safety and performance, just as before."

An independent economic impact study by the Brattle Group, published last September by the Pennsylvania State Building & Construction Trades Council, found that the restart will create 3,400 direct and indirect jobs, add USD16 billion to Pennsylvania's GDP and generate more than USD3 billion in state and federal taxes.

At the time of its closure in 2019, Three Mile Island unit 1 had an operating licence valid until 2034. Constellation is looking to extend operations to at least 2054 and expects the plant to be ready for service by 2028. The NRC expects to complete its review of Constellation's application to change the name of the plant by 23 May.