Nuclear weapons

Weapon Designs

• Gun-triggered fission
• Implosion-triggered fission
• Fusion Bombs

Gun-triggered

• This is the simplest form of nuclear weapon.
• A bullet of U-235 is propelled by explosives into a U-235 sphere.
• Because of the relatively slow combination of the critical mass, this method works only with U-235.
• This is the type of bomb that destroyed the Japanese city of Hiroshima.

Gun-triggered

Implosion-triggered

• A sub critical sphere of plutonium is surrounded by explosives, when the explosives detonate they create a shockwave which compresses the core.
• The increased density of the core causes it to become supercritical, and the nuclear reaction begins.
• This method can be used with both U-235 and Pu-239.
• This is the type of weapon detonated at the Trinity site, and on the Japanese city of Nagasaki.
• To properly compress instead of blowing it apart, it is necessary to use explosive lenses, which create a concave shockwave that fits the surface of the core.