There are more ways than ever to listen to History Daily ad-free.

Listen with Wondry Plus in the Wondry app.

As a member of NoisorPlus at noisor.com or in Apple Podcasts,

or you can get all of History Daily plus other fantastic history podcasts at IntoHistory.com. It's March 28, 1979, at the 3-mile island nuclear power station near Harrisburg, Pennsylvania.

It's a few minutes before 4 a.m., and the shift foreman, Frederick Shimon, is attending to some paperwork in his office.

In the basement below, two other men, Donald Miller and Harold Fars, are taking care of some

routine maintenance. And as the clock nears 4 a.m. on the dot, Frederick decides to check

in on their progress. On arriving, Frederick finds Donald and Harold cleaning out the pipes that feed and purify

cooling water into one of the plant's reactors. Donald beckons Frederick over and explains that

there's a slight plumbing problem. One of the pipes that carries away impurities is blocked.

He goes on to explain that they've been trying for the best part of an hour

to flush away the blockage, but it's yet to budge. Frederick frowns, because this is unusual.

He peers into a glass window on one of the pipes to try and figure out what the issue might be.

But as he inspects the machinery closer, he hears a sudden, loud crashing noise.

And then the building's loudspeakers blare an alarm that there has been a turbine trip,

a reactor trip. Frederick rushes to the control room, where he finds workers in a frenzy.

No one is sure what to do because most, Frederick included,

received little training to work at the plant, let alone handle any kind of meltdown.

But as they argue over what to do first, the crashing sound stops.

Frederick looks at the clock. It's 37 seconds past 4 a.m., and the reactor has shut down.

Immediately, the automatic emergency cooling system begins.

But when Frederick and his team checked the water readings,

...