1983 that the powerplant was "one of the most dangerous nuclear powerplants in the USSR". 1986 reactor #4 catastrophe (Chernobyl disaster) On 26 April 1986, the Chernobyl disaster occurred at reactor No. 4, caused by a catastrophic power increase resulting in core explosions and open-air fires. This caused large quantities of radioactive materials and airborne isotopes to disperse in the atmosphere and surrounding land. The disaster is regarded as the worst accident in the history of nuclear power. As a result, Reactor No. 4 was destroyed entirely, and therefore enclosed in a concrete and lead sarcophagus, followed more recently by a large steel confinement shelter to prevent further escape of radioactivity. Large areas of Europe were affected by the accident. The radioactive cloud spread as far away as Norway. 1991 reactor #2 turbine fire Reactor No. 2 was permanently shut down shortly after October 1991 when a fire broke out due to a faulty switch in a turbine. On 11 October 1991, a fire broke out in the turbine hall of reactor No. 2. The fire began in reactor No. 2's fourth turbine, while the turbine was being idled for repairs. A faulty switch caused a surge of current to the generator, igniting insulating material on some electrical wiring. This subsequently led to hydrogen, used as a coolant in the synchronous generator, being leaked into the turbine hall "which apparently created the conditions for fire to start in the roof and for one of the trusses supporting the roof to collapse." The adjacent reactor hall and reactor were unaffected, but due to the political climate it was decided to shut down this reactor permanently after this incident. 2017 cyberattack The 2017 Petya cyberattack affected the radiation monitoring system and took down the power plant's official website, which hosts information about the incident and the area. 2022 Russian invasion of Ukraine The Chernobyl Exclusion Zone was the site of fighting between Russian and Ukrainian forces during the Battle of Chernobyl as part of the Russian invasion of Ukraine. On 24 February 2022, Russian forces captured the plant. The resulting activity reportedly led to a 20-fold increase of radiation levels in the area due to disruption of contaminated soil. The increase in radiation levels was published on an online map maintained by a Ukrainian NGO, but the corresponding sensors at the plant itself exhibited no increase. On 9 March 2022, there was