40 Years After A Partial Nuclear Meltdown, A New Push To Keep Three Mile Island Open

Forty years ago, the most serious nuclear accident in U.S. history sparked a backlash against the industry and halted its growth for decades. Today, the remaining working reactor at Three Mile Island, Unit 1, faces new challenges, including cheaper competition in a rapidly shifting energy grid. Unit 1 at the plant, near Harrisburg, Penn., is slated to close later this year.

But mounting concerns about climate change, and the need for zero-carbon power, are also driving a new push to keep Three Mile Island and other nuclear reactors open. It's a turnaround few would have foreseen in the chaotic days after the accident.

Confusion and fear

On March 28, 1979, Three Mile Island's Unit 2 reactor suffered a partial meltdown after a pump stopped sending water to the steam generators that removed heat from the reactor core. The accident was a combination of human error, design deficiencies, and equipment failures.

The incident happened around 4 a.m. on a Wednesday, but it took several days before people understood the severity of the problem, as public officials struggled to explain what was happening. By Friday, then-Governor Dick Thornburgh recommended pregnant women and young children evacuate.