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Summary
On April 26, 1986, the world's worst nuclear power plant accident occurs at the Chernobyl nuclear power station in the Soviet Union. Thirty-two people died and dozens more suffered radiation burns in the opening days of the crisis, but only after Swedish authorities reported the fallout did Soviet authorities reluctantly admit that an accident had occurred. Ironically the disaster that has become synonymous with the dangers of nuclear energy was caused in part by a safety test. The power-regulating system and emergency safety system of the fourth reactor at Chernobyl in Ukraine were shut down for the test on April 25. Most of the control rods (the reactor components that stop nuclear fission from cascading out of control) were withdrawn from the nuclear core, while engineers allowed the reactor to operate at 7 percent power. At 1:23 a.m. on April 26, the fourth reactor experienced an enormous power excursion, or sudden increase in the power level. This caused a steam explosion, and hydrogen escaped to the outside air. The hydrogen mixed with oxygen and ignited, triggering a chemical explosion. This second explosion ripped the roof off of the reactor, exposing its radioactive core. Worse yet, it ejected an enormous amount of highly radioactive particulate and gaseous debris into the atmosphere, the majority of which drifted to Belarus. The effort to contain the resulting fire and cleanup is tragic and well-documented. Firefighters rushed to the scene to put out the blaze, many exposing themselves to deadly levels of radiation in the process. The fire was finally put out at 6:35 a.m. the following morning, but the exposed radioactive core remained. Soviet engineers scrambled to come up with a containment solution. Workers wearing heavy protective suits shoveled radioactive debris into what remained of the reactor. This cleanup crew could only be on the rooftops of surrounding buildings for a maximum of 40 seconds, because the radiation levels were so high.
