Three Mile Island: The Reactor That Nearly Broke
A partial meltdown in Pennsylvania froze the American nuclear dream and rewired how the world feared the atom.
WOW Score
A cooling malfunction at the Three Mile Island plant near Harrisburg, Pennsylvania, led to a partial meltdown of one reactor's core.
Conflicting information and uncertainty about a possible release of radiation caused widespread fear and the evacuation of nearby families.
Though the off-site release was small, the crisis shattered confidence in nuclear power's safety.
"A stuck valve and a misread gauge let a reactor core overheat. For days, the nation wondered if it would blow."
The 1979 accident was the worst commercial nuclear incident in U.S. history. It halted the growth of nuclear power for decades and entrenched public anxiety about atomic energy.
The Full Story
The Cascading Failure
A relief valve stuck open and instruments misled operators, allowing the core to heat dangerously before the situation was understood.
Days of Doubt
Confusing official statements fed public alarm, even as the actual release remained limited.
A Changed Industry
New safety rules, training, and a halt to plant orders followed; nuclear construction in the U.S. largely stalled for a generation.