Alexei Ananenko, Valeri Bezpalov, and Boris Baranov
The Chernobyl Disaster, in which a reactor exploded at the Chernobyl Nuclear Power Plant in modern-day Ukraine, is one of the worst accidents to ever occur at a nuclear power plant and yet it could have been so much worse.
After the plant’s cooling systems failed, a pool formed under the highly unstable reactor. With safety systems unoperational, it was only a matter of time before the reactor dropped into the pool of water and set off a steam explosion, sending radiation all over Europe. One expert predicted the explosion would obliterate Minsk (320 kilometers away) and make Europe inhospitable.
Alexei Ananenko was the only man who knew where the pressure release valve was and, along with engineer Valeri Bezpalov and shift supervisor Boris Baranov, volunteered to undertake what amounted to a suicide mission.
The men were (obviously) successful.
They died of radiation poisoning a few weeks later and were buried in lead coffins.