The Chernobyl disaster was a catastrophic nuclear accident that occurred on 26 April 1986 at the Chernobyl Nuclear Power Plant in Ukraine, which was under the direct jurisdiction of the central authorities of the Soviet Union. The Chernobyl disaster is the worst nuclear power plant accident in history in terms of cost and resulting deaths, and is one of only two classified as a level 7 event (the maximum classification) on the International Nuclear Event Scale (the other being the Fukushima Daiichi nuclear disaster in 2011). Photo: Graffiti of a crying baby on a wall, Chernobyl Power Plant, Chernobyl, Ukraine. (Photo by Hans Neleman/Getty Images)

In this photo taken Tuesday, June 23, 2015, a Ukrainian serviceman from the Kiev-2 volunteer battalion fires an weapon at a frontline in the village of Krymske, east Ukraine. Few places along the front line in east Ukraine see regular fighting as bitter as the village of Krymske. For now, Krymske is in the hands of Ukrainian government forces and the volunteer battalions that fight alongside them. (Photo by Evgeniy Maloletka/AP Photo)

A woman jumps with balloons while she poses for a picture at a park in Kiev, Ukraine May 6, 2018. (Photo by Valentyn Ogirenko/Reuters)

Models wait backstage during Ukrainian Fashion Week in Kiev, Ukraine, October 12, 2016. (Photo by Gleb Garanich/Reuters)

Revellers dance at a rave party in central Kyiv, Ukraine on August 27, 2022. (Photo by Vladyslav Musiienko/Reuters)

A dog plays with a giant soap bubble in downtown Kiev, Ukraine, 06 March 2020. (Photo by Sergey Dolzhenko/EPA/EFE)

Bogdana, 17, laughs with her boyfriend, Ivan, 19, in Brovary, Ukraine, Sunday, March 20, 2022. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (Photo by Vadim Ghirda/AP Photo)

A handout picture provided by the Vatican Media shows Pope Francis holding a flag of Ukraine that was sent to him from the Ukrainian town of Bucha during the weekly general audience in the Paul VI Audience Hall, in Vatican City, 06 April 2022. The pontiff lamented the “massacre of Bucha”, in the Kyiv suburb where dozens of bodies in civilian clothing have been found, and renewed his calls for an end to the war in Ukraine. (Photo by Vatican Media Handout/EPA/EFE)