epa02602869 General view of the fourth energy block of the Chernobyl nuclear power plant which was damaged in the worst nuclear power accident in history in April 1986, Ukraine, photographed on 22 February 2011. One of two reactors at the Chernobyl nuclear power station exploded in a power test in 1986. Ukrainians will mark the 25th anniversary of the world’s yet worst nuclear power accident on 26 April 2011. EPA/SERGEY DOLZHENKO