NEW YORK/PHILADELPHIA (Reuters) - Constellation Energy ( CEG ) is in talks with the Pennsylvania governor's office and state lawmakers to help fund a possible restart of part of its Three Mile Island power facility, the site of a nuclear meltdown in the 1970s, three sources familiar with the discussions said on Tuesday. The conversations, which two sources described as "beyond preliminary," signal that Constellation is advancing plans to revive part of the southern Pennsylvania nuclear generation site, which operated from 1974 to 2019. The nuclear unit Constellation is considering restarting is separate from the one that melted down.

No U.S. nuclear power plant has been reopened after shutting. A restart is expected to be costly, logistically challenging and met with public and political opposition over safety and environmental concerns.

Still, as the United States faces a sudden rebound in power demand from industries like technology, the virtually carbon-free electricity source has received fresh support.

The sources said that a shut Michigan nuclear plant, which was recently awarded a $1.5 billion conditional loan to restart from the administration of U.S. President Joe Biden, could serve as a private-public sector blueprint for Three Mile Island.

The sources asked not to be named due to the sensitivity of the discussions.

"Though we have determined it would be technically feasible to restart the unit, we have not made any decision on a restart as there are many economic, commercial, operational and regulatory considerations remaining," Constellation spokesperson Dave Snyder said in an email. Snyder did not comment on the specifics of discussions about reopening the Pennsylvania site. Shares of Constellation, which is based in Baltimore, Maryland, have risen roughly 80% this year on the prospect of the company cashing in on big tech's voracious demand for carbon-free electricity to power a rapid expansion of technologies such as generative artificial intelligence. Last month, Constellation told Reuters that it had cleared an engineering study of Three Mile Island, though it was unknown if the Baltimore, Maryland-based energy company would move forward with plans to reopen the site.

Constellation also said that given the current premium placed on nuclear energy, acquiring other sites was generally off the table and the company would instead look to expand its existing fleet. The Three Mile Island unit that could be restarted is different to the site's unit 2, which experienced a partial meltdown in 1979 in the most famous commercial nuclear accident in U.S. history.