Ukraine's President Viktor Yanukovich takes part in a ground-breaking ceremony for a new containment shelter to be built at the site of the Chernobyl nuclear plant near Chernobyl city April 26, 2012. Belarus, Ukraine and Russia marked the 26th anniversary of the Chernobyl disaster, the world's worst civil nuclear accident, on Thursday. REUTERS/Gleb Garanich (UKRAINE - Tags: DISASTER ENERGY ANNIVERSARY POLITICS)