Documentary: TSAR Bomb and Thermonuclear Warhead - - The largest nuclear bomb ever tested.. October 30, 1961... The Tsar Bomb.. Soviet era 50 megaton = 50 millions tons of TNT. Total destruction - 15 mile radius.. 3rd degree burns - 64 mile radius .. visible 600 miles away. Original design was to be 100 megaton - - "According to the Center for Defense Information, there are approximately 30,000 intact nuclear warheads worldwide.. All but about 200 are retained by the United States and Russia"