9. The Near-Miss at Three Mile Island (1979)
On March 28, 1979, the Three Mile Island Unit 2 reactor in Pennsylvania experienced a partial meltdown due to a combination of equipment failures and operator errors. The incident led to the release of a small amount of radioactive gases into the atmosphere, but no immediate health effects were observed. The crisis was narrowly averted, preventing a potentially catastrophic release of radiation (history.com).
