The Chernobyl nuclear accident occurred on April 26, 1986, at Reactor No. 4 of the Chernobyl nuclear power plant near Pripyat, Ukraine, then part of the Soviet Union. The radioactive release was hundreds of times greater than that of the atomic bombs dropped on Hiroshima and Nagasaki, according to major media reports.
The accident was caused by a combination of human error and a flawed reactor design (RBMK), according to major media reports. Operators switched off almost all safety features before conducting an emergency shutdown test, which was intended to check if the reactor could operate for 40-45 seconds without power. According to Metro - Main, former nuclear engineer Vince Zabielski described that unlike Western reactors, there was no containment structure to limit the release.
Unlike Western reactors, there was no containment structure to limit the release. Its scale, severity, and enduring impact set it apart from all other nuclear accidents. As a condition of entry into the EU, all countries using the RBMK design had to permanently cease operations.
Two plant workers were killed within hours of the meltdown, and 28 people died from radiation poisoning, including firefighters. Thousands or possibly millions have died from radiation-associated illnesses, according to major media reports. The exact number of deaths attributable to the disaster remains unknown.
The Soviet Union initially suppressed information about the accident, according to major media reports. The Soviet news agency Tass confirmed a reactor had failed at Chernobyl two days after the accident, following detection of elevated radioactivity at Forsmark nuclear plant in Sweden. Radioactive fallout was detected across northern and central Europe.
The KGB and Stasi kept detailed records of the disaster but only top officials had access, according to major media reports. Firefighters worked through the night without adequate protective equipment, according to major media reports.