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)

Kacey Musgraves performs at the 49th annual CMA Awards at the Bridgestone Arena on Wednesday, November 4, 2015, in Nashville, Tenn. (Photo by Chris Pizzello/Invision/AP Photo)

Fighters battle in Manhattan's Union Square during a massive pillow fight on April 2, 2011 in New York City. Over 130 cities worldwide are participating in the fourth annual International Pillow Fight Day. (Photo by Mario Tama/Getty Images)

Workers use a boat to recover supplies from a flooded grain elevator May 4, 2011 in Caruthersville, Missouri. Heavy rains have left the ground saturated, rivers swollen, and has caused widespread flooding in Missouri, Illinois, Kentucky and Arkansas. (Photo by Scott Olson/Getty Images)

JAPAN: A businessman stands at a pond in the Kyu-Shiba-rikyu Garden on a warm and sunny day in Tokyo, Japan, March 18, 2016. (Photo by Thomas Peter/Reuters)

VIETNAM: A Vietnamese woman, wearing the traditional “ao dai” long dress, poses for photos along peach blossom flowers ahead of the Vietnamese “Tet” (Lunar New Year festival), in a field in Hanoi, Vietnam, February 2, 2016. (Photo by Reuters/Kham)

CANADA: Stanley Ferdinand filets large trout he caught in Great Bear Lake in Deline, Northwest Territories, Canada September 8, 2016. (Photo by Pat Kane/Reuters)

A woman carries a water pump to work on February 11, 2017 in Almolonga, Guatemala. The Mayan town in the western highlands district of Quetzaltenango has surged in prosperity in recent years with high-productivity vegetable farming, exporting much of its excess crops to neighborning El Salvador. (Photo by John Moore/Getty Images)