In this March 23, 2016, file photo, a worker checks the radiation level on barrels in a storage of nuclear waste taken from the 4th unit destroyed by the 1986 explosion at the Chernobyl nuclear power plant, Chernobyl, Ukraine. A new and highly virulent outbreak of data-scrambling software — apparently sown in Ukraine — caused disruption across the world Tuesday, June 27, 2017. The virus hit the radiation-monitoring at Ukraine's shuttered Chernobyl power plant, site of the world's worst nuclear accident, forcing it into manual operation. (AP Photo/Efrem Lukatsky)