What Day Was the Chernobyl nuclear disaster?

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Reactor No. 4 at the Chernobyl Nuclear Power Plant in the Soviet Union (in present-day Ukraine) exploded during a safety test, releasing large quantities of radioactive material and triggering the evacuation of the nearby city of Pripyat.

It remains one of the two events rated at the maximum level 7 on the International Nuclear Event Scale, alongside the 2011 Fukushima disaster.

Soviet authorities did not publicly acknowledge the disaster until Swedish monitoring stations, over a thousand kilometers away, detected abnormal radiation levels and traced them back to the USSR, forcing an admission days later.

The surrounding exclusion zone remains largely uninhabited by permanent residents decades later, though it has become an unusual haven for wildlife in the near-total absence of human activity.

The disaster prompted major reforms to Soviet-era nuclear safety culture and openness policy, and is often cited by historians as one of the contributing pressures behind the broader glasnost reforms of the late 1980s.