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
Chernobyl disaster and Nagasaki, to assess the long-term effects of radiation on human health. The number of potential deaths arising from the Chernobyl disaster is heavily debated. The WHO's prediction of 4000 future cancer deaths in surrounding countries is based on the Linear no-threshold model (LNT), which assumes that the damage inflicted by radiation at low doses is directly proportional to the dose. Radiation epidemiologist Roy Shore contends that estimating health effects in a population from the LNT model "is not wise because of the uncertainties". According to the Union of Concerned Scientists the number of excess cancer deaths worldwide (including all