The owner of the shuttered Three Mile Island nuclear power plant said Friday that it plans to restart the reactor under a 20-year agreement that calls for tech giant Microsoft to buy the power to supply its data centers with carbon-free energy.

The site was ground zero for a partial nuclear meltdown in 1979, which affected a separate unit and caused nearby areas to evacuate

The 20-year deal with Constellation Energy would kick-start the site of the nation’s worst nuclear accident.