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)

A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

Swiss pilot Bertrand Piccard prepares for a test flight of the solar-powered Solar Impulse 2 experimental aircraft in Payerne November 13, 2014. The aircraft, weighing 2.4 tons with a wingspan of 72 meters, is fitted with more than 17,000 solar cells. An attempt to fly around the world in stages using only solar energy will be made in 2015. (Photo by Ruben Sprich/Reuters)

In this photo taken on Saturday, April 29, 2017, a candle is lit in a roadside shrine as the sun sets across a nearby lake of Pineia in the village of Souli, in the Peloponnese region of southern Greece. Made of iron sheeting, stone, wood, concrete or marble, tens of thousands of such shrines punctuate Greece’s roadside scenery, a common sight in a country that has one of the European Union’s worst road fatality rates. (Photo by Petros Giannakouris/AP Photo)

Migrants scramble aboard a train at the station in Beli Manastir, Croatia September 18, 2015. Migrant numbers in Europe will build up in coming days and their flows may fragment further into new routes, the U.N. refugee agency said on Friday, urging the European Union to grasp a last chance to resolve the refugee crisis next week. (Photo by Laszlo Balogh/Reuters)

A destroyed T-72 tank, which presumably came from Russia, is seen on a battlefield near separatist-controlled Starobesheve, eastern Ukraine, October 2, 2014. The burnt-out remains of dozens of tanks and armoured vehicles in fields near the small village of Horbatenko bear witness to the ferocity of a battle that turned the tide of the conflict in eastern Ukraine. Among the debris, Reuters found the blackened carcasses of what military experts have since identified as two Russian army tanks, supporting statements by Kiev and the West that the rebels were backed by troops and equipment sent by Moscow. (Photo by Maria Tsvetkova/Reuters)

Two Teddy Bears from the 1920's sit on display in the museum section of the Merrythought Teddy Bear shop on April 5, 2011 in Ironbridge, England. Established in 1930, Merrythought has been hand-making Teddy Bears for over 80 years in Shropshire. The family-run company is the last remaining British teddy bear factory and is launching its latest limited edition bear to mark the royal wedding. The Commemorative Royal Wedding bear is limited to 75 and comes after its popular Prince William and Catherine Middleton bears completely sold out. Merrythought has also been selected by the London Olympic Games organisers to produce the official teddy bears of the London 2012 Olympic and Paralympic games. (Photo by Christopher Furlong/Getty Images)