Atom Bom

++The Hiroshima Bomb (Little Boy)++ Length: Approx. 3 meters (120 inches) Weight: Approx. 4 tons (9,000 lbs)  Diameter: Approx. 0.7 meters (28 inches) Element: Uranium 235 Because of its long, thin shape, the Hiroshima bomb was called Little Boy. The fissile material was uranium 235. The uranium was divided into two parts, both of which were below critical mass. It was a "gun barrel-type" bomb that used an explosive device to slam one portion of uranium into the other, instantly creating a critical mass.  When a critical mass is available, a chain reaction takes place instantaneously, releasing energy far beyond the capacity of ordinary explosives. The energy released by the Hiroshima bomb was originally thought to be equivalent to the destructive power of approximately 20,000 tons of TNT. Later estimates based on damage to buildings and studies of the bomb's structure have reduced that figure to approximately 15,000 tons. It is believed that this enormous energy was released by the fission of slightly less than one of the 10 to 35 kilograms of uranium 235 in thebomb.

Length: Approx. 3.2 meters (128 inches) Weight: Approx. 4.5 tons (10,000 pounds) Diameter: Approx. 1.5 meters (60 inches) Element: Plutonium 239 Compared to the one used on Hiroshima, the Nagasaki bomb was rounder and fatter, so it was called "Fat Man." The fissile material was plutonium 239. The plutonium was divided into subcritical portions and packed into a spherical case. To cause the chain reaction, gunpowder around the periphery of the case was used to force the units to the center. Thus, it was called an "implosion-type" bomb. The fission of slightly more than one kilogram of plutonium 239 is thought to have released destructive energy equivalent to about 21,000 tons of TNT.