A guard stands at Dityatki checkpoint, marking a 30 km (18-mile) zone around the Chernobyl nuclear power plant April 23, 2013. Ukraine will mark the 27th anniversary of the Chernobyl disaster, the world's worst civil nuclear accident, on April 26. (Photo by Gleb Garanich/Reuters)

A stray puppy walks along abandoned train tracks near the Chernobyl nuclear power plant on August 19, 2017 near Chornobyl, Ukraine. An estimated 900 stray dogs live in the exclusion zone, many of them likely the descendants of dogs left behind following the mass evacuation of residents in the aftermath of the 1986 nuclear disaster at Chernobyl. (Photo by Sean Gallup/Getty Images)

A stuffed rabbit doll sits among children's beds standing in the abandoned kindergarten of Kopachi village located inside the Chernobyl Exclusion Zone on September 29, 2015 near Chornobyl, Ukraine. Kopachi, a village that before 1986 had a population of 1,114, lies only a few kilometers south of the former Chernobyl nuclear power plant, where in 1986 workers inadvertantly caused reactor number four to explode, creating the worst nuclear accident in history. (Photo by Sean Gallup/Getty Images)

A doll in a children's gas mask is seen amongst beds at a kindergarten in the abandoned city of Pripyat near the Chernobyl nuclear power plant in Ukraine on March 28, 2016. Deadly radiation still spews from Chernobyl 30 years after the worst nuclear meltdown in history, as a newly built giant arch is pulled into place to cover the stricken reactor for the next century. (Photo by Gleb Garanich/Reuters)

A painting of a Trabant car bursting through a wall in post unification Berlin, August 1993. (Photo by Steve Eason/Hulton Archive/Getty Images)

Grafitti by the illusive artist Banksy adorns the levee wall in the Lower Ninth Ward on August 29, 2008 in New Orleans, Louisiana. New works by the artist, whose paintings are also sold in galleries, have been popping up throughout New Orleans coinciding with the third anniversary of Hurricane Katrina. (Photo by Chris Graythen/Getty Images)

Women spray their designs on a wall during a graffiti class offered by the LATA 65 organization in Lisbon, Portugal May 14, 2015. The LATA 65 organization is an initiative for the elderly in the area of urban art. Since it began in 2012, they have introduced the world of graffiti to over 100 senior citizens, giving workshops in different neighborhoods of Lisbon. (Photo by Rafael Marchante/Reuters)

Visitors look at graffiti art created by Brazilian artist Image during the 3rd annual Graffiti Fine Art Biennial International exhibit, at the Pavilion of Brazilian Cultures, in Sao Paulo, Brazil, Tuesday, April 21, 2015. The month-long event features the work of more than 60 street artists, representing 11 countries. (Photo by Andre Penner/AP Photo)