CHORNOBYL, UKRAINE - AUGUST 18: Stray puppies play in an abandoned, partially-completed cooling tower inside the exclusion zone at the Chernobyl nuclear power plant on August 18, 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. Volunteers, including veterinarians and radiation experts from around the world, are participating in an initiative called The Dogs of Chernobyl, launched by the non-profit Clean Futures Fund. Participants capture the dogs, study their radiation exposure, vaccinate them against parasites and diseases including rabies, tag the dogs and release them again into the exclusion zone. Some dogs are also being outfitted with special collars equipped with radiation sensors and GPS receivers in order to map radiation levels across the zone. (Photo by Sean Gallup/Getty Images)