Chernobyl disaster Chernobyl disaster The Chernobyl disaster, also referred to as the Chernobyl accident, was a catastrophic nuclear accident. It occurred on 25–26 April 1986 in the No. 4 light water graphite moderated reactor at the Chernobyl Nuclear Power Plant near the now-abandoned town of Pripyat, in northern Ukrainian Soviet Socialist Republic, Soviet Union, approximately north of Kiev. The event occurred during a late-night safety test which simulated a station blackout power-failure, in the course of which safety systems were intentionally turned off. A combination of inherent reactor design flaws and the reactor operators arranging the core in a manner contrary to
Effects of the Chernobyl disaster tended to be longer-lived than those released by the detonation of atomic bombs. According to a 2009 United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), the Chernobyl accident had by 2005 caused 61,200 man-Sv of radiation exposure to recovery workers and evacuees, 125,000 man-Sv to the populace of the Ukraine, Belarus, and Russia, and a dose to most of the more distant European countries amounting to 115,000 man-Sv. The same report estimated a further 25% more exposure would be received from residual radiosotopes after 2005. The total global collective dose from Chernobyl was earlier estimated by UNSCEAR