Constellation Energy plans to restart the Unit 1 reactor at Three Mile Island. It will sell the power to Microsoft to support the power needs of data centers. Unit 1 is separate from the reactor that partially melted down in 1979 in the worst nuclear accident in U.

Constellation Energy Generation LLC, the largest renewable energy producer in the U.S., announced the initiative today. The company will supply power from Three Mile Island to Microsoft under a newly signed 20-year contract. Before reopening the plant, Constellation will carry out wide-ranging renovations and secure fresh regulatory approvals.

A new deal would restart the nuclear power station’s Unit 1 reactor by 2028. Microsoft has committed to buy electricity generated, to run its data centers. The plant’s condition has received good reviews but capital investments will be needed.