Could nuclear power restart at Three Mile Island? Here’s what to know about the plant’s history amid questions about its future.

It’s been half a decade since Three Mile Island provided power to Pennsylvania, but one of the nuclear plant’s decommissioned reactors might have a restart in its future.

Three Mile Island owner Constellation Energy Corporation is in talks with Gov. Josh Shapiro’s office and state lawmakers to potentially bring the site’s Unit 1 reactor back online, according to a recent report from Reuters. That reactor is separate from the infamous Unit 2 reactor, which suffered a partial meltdown in 1979, and has been dormant ever since.

Unnamed sources told Reuters that the talks were “beyond preliminary,” but neither the governor’s office nor Constellation Energy has publicly confirmed that a restart is imminent.

Constellation Energy, which operates more than a dozen nuclear power plants nationwide (including two others in Pennsylvania), has “not made any decision,” but has determined a restart would be “technically feasible,” a company spokesperson told Reuters. Shapiro’s office, meanwhile, told the Susquehanna Valley’s Fox 43 that it “recognizes the role Pennsylvania’s nuclear generation fleet plays in providing safe, reliable, carbon-free electricity,” but did not confirm the talks.

» READ MORE: A nuclear accident made Three Mile Island infamous. AI’s needs may revive it.

Rumblings of a potential restart at Three Mile Island comes amid a renewed interest in nuclear energy in nationally and in Harrisburg, with lawmakers earlier this month announcing the relaunch of a bipartisan Nuclear Energy Caucus that will work to shore up the state’s nuclear power industry. And earlier this year, the Department of Energy announced a $1.5 billion loan to reopen a Michigan-based nuclear plant that shut down in 2022.

But, as Reuters reported, any restart would likely face roadblocks due to safety and environmental concerns, as well as economic and logistical issues. Three Mile Island, after all, is the home of what is considered to be the worst nuclear accident in U.S. history thanks to its partial meltdown more than 40 years ago. Here is what you need to know:

Located on the Susquehanna River about 10 miles outside Harrisburg, Three Mile Island’s Unit 2 reactor went online in December 1978 — four years after Unit 1 started producing power. Three months later, on March 28, 1979, Unit 2′s partial meltdown started after a ”malfunction….caused a slight leakage of radiation into the atmosphere,” according to an Inquirer report from the time.

That malfunction caused a shutdown of the facility, which was evacuated. State officials learned of the incident hours later, prompting them to declare a “general emergency” — the first ever at a nuclear reactor, the Inquirer reported.

Lt. Gov. William Scranton called the incident “minor” in its immediate aftermath, but later told reporters that the situation was more complex than representatives from the plant’s then-operator, Metropolitan Edison, led officials to believe. Officials would later report that people living within five to 10 miles of the plant were potentially exposed to about 10 times as much radiation as Met Ed officials estimated.

Officials at the time indicated that a total meltdown was not likely, and there was no “imminent danger” of a public health threat, the Daily News reported. However, the formation of a “hydrogen bubble” threatened the possibility of a total meltdown — but that was avoided after the bubble began shrinking.

There were no reported deaths or injuries, but more than 140,000 people temporarily evacuated the area, according to Popular Mechanics.

In the wake of the partial meltdown, the Bechtel Corporation began leading a billion-dollar cleanup of the Unit 2 reactor. A senior startup engineer, Richard Parks, however, became a whistleblower, alleging that the company and plant operator were taking safety shortcuts.

Parks would go on to work with the Government Accountability Project to file a 56-page affidavit with the U.S. Department of Labor detailing the alleged safety issues. Central to the allegations, The Inquirer reported in 1983, were Parks’ concerns over a piece of equipment at the top of the reactor that would be used in the cleanup. The issue, Parks said, was that the equipment was damaged during the accident, and needed to be refurbished and tested to ensure its safety — and that he had been harassed by the company and relieved from a number of duties for his concern.

In November 1983, a federal grand jury accused Met Ed of falsifying tests showing whether excessive water was leaking from the cooling system, and systematically destroying records of those tests. Ultimately, Met Ed pleaded guilty to falsifying records, and was ordered to pay a $45,000 fine and create a $1 million fund to help clean up the plant.

In 2019, EnergySolutions Inc. announced that it would acquire Unit 2 in order to decommission and dismantle it — a process that remains ongoing. TMI-2 Solutions, a subsidiary of the company, estimates that the process will be complete by 2038.

Unit 1 was not taken out during Unit 2′s 1979 partial meltdown. In fact, it remained operational for decades, providing power to some 830,000 homes throughout its run.

But that run came to an end on Sept. 20, 2019, when Unit 1 was finally disconnected from the power grid after 45 years in operation. Its closure wasn’t a surprise — the plant’s owner, then known as Exelon, had announced in 2017 that it would shut down the reactor.

At the time, the company said a shutdown was imminent unless the Pennsylvania legislature rescued the state’s nuclear industry, which was struggling to compete amid electricity prices driven down amid newfound natural-gas resources. In the five years before the impending closure was announced, Exelon said, Unit 1 had lost more than $300 million, despite being one of its most efficient units.

“We’re not going to be able to cost-cut ourselves out of this situation we’re in,” David Fein, an Exelon Corp. vice president for state government affairs, told The Inquirer in 2017. “There needs to be some policy changes to address the market flaws and market challenges we’re seeing.”

That change, however, never came.

Today, the decommissioning of Unit 1 remains in process. If the reactor isn’t restarted, that effort is expected to cost an estimated $1.2 billion in total. And it wouldn’t be completed for roughly 60 years, with a projected finish date sometime in 2079, The Inquirer reported.