On April 26, 1986, a routine test on reactor No. 4 at the Chernobyl nuclear power plant went horribly wrong. The reactor in Ukraine, in the old Soviet Union, went into meltdown. It became the world’s worst peacetime nuclear disaster.
A power surge during the test led to a rupture and a series of steam explosions. There was a massive leak of radiation, leading to fallout eventually landing all across Europe.
Dozens died in the struggle to contain the disaster. Hundreds of thousands of people were evacuated.