14. The first level 7 – the maximum severity – nuclear energy incident, the failure at the Chernobyl Nuclear Power Plant spread radioactive material over 100,000 square kilometers
The Chernobyl disaster was a catastrophic nuclear energy accident, occurring on April 25-26, 1986, at the Chernobyl Nuclear Power Plant near the town of Pripyat, in northern Ukraine. During a late-night test simulating a station blackout, requiring the plant’s safety systems to be deactivated, the reactor went critical. Water was flash-heated into steam, triggering an explosion and an open-air graphite fire that dispersed radioactive fumes across the surrounding environment. Spreading across a vast area, the 50,000 residents of Pripyat were immediately evacuated and the town abandoned as part of a 2,600 square kilometer exclusion zone; this zone will not be habitable by humans again for another 20,000 years.
Although the initial 1986 investigation blamed the operators of the plant, a subsequent report in 1992 revealed extensive engineering and design faults in the facility itself. Serious structural issues, such as splitting concrete, were never addressed by contractors, whilst the design of the control rods was inadequate and the reactor was fundamentally dangerous. Identifying 29 emergency situations at the plant between 1971 and 1986, only 8 were caused by plant personnel. The consequences of Chernobyl are hard to calculate, with the lasting effects not fully observable for decades, but at least 50 people are estimated to have died as a direct result of exposure to radioactive materials to date.