The most powerful US nuclear bomb

The B53 is the oldest nuclear bomb in the USA's Cold War arsenal - one of the most powerful it ever built. With a yield of 9 megatons of TNT (38 PJ), was the most powerful weapon in the US nuclear arsenal after the dismantling of the B41 nuclear bomb.

In comparison the atomic bomb that was dropped on Nagasaki in 1945 is rated at 21 kilotons, meaning the B53 is more than 400 times more powerful. Little Boy, the atomic bomb that was dropped on Hiroshima is even less powerful at around 18 kilotons.

Built at the height of the Cold War in 1962, it was designed to be dropped onto a target by a B-52 Stratofortress strategic bomber. Upon detonation at optimum height, it would result in a fireball with an approximate 4 to 5 km in diameter, the radiated heat sufficient to burn to death people within a 28.7 km radius (2,580 sq km). The resulting blast would collapse most residential and industrial structures within a 14.9 km radius (780 sq km). Within 5.7 km virtually all above-ground structures would be destroyed and blast effects would inflict near 100% fatalities.

It was kept at the B&W Pantex nuclear weapons storage facility outside Amarillo, Texas.

As part of President Obama's nuke policy, it was finally dismantled on 25th October 2011, meaning the most powerful nuke bomb in USA is now the B83, at 1.2 megatons.