backpack gun

A suitcase nuclear device (also suitcase nuke, suitcase bomb, backpack nuke, mini-nuke, and pocket nuke) is a tactical nuclear weapon that is portable enough that it could use a suitcase as its delivery method.
Both the United States and the Soviet Union developed nuclear weapons small enough to be portable in specially-designed backpacks during the 1950s and 1960s.The maximum yield of the W54 warhead used in the Special Atomic Demolition Munition (pictured) was 1 kt (1000 tonnes of TNT equivalent). This is larger and heavier than the US W48 nuclear shell at 155 mm (6.1 inches) in diameter and 846 mm (33.3 inches) long and weighing 53.5 kg (118 lb), which represents the smallest complete, self-contained physics package to be fielded and had a yield of 72 tonnes of TNT. Nuclear weapons designer Ted Taylor has alleged that a 105 mm (4.1 inch) diameter shell with a mass of 19 kg is theoretically possible. Conversely, reduction beyond the size of the W54 means that linear implosion designs must be employed and neutron reflectors dispensed with ("bare core"), so a much larger mass of fissile material is required and explosive yield is reduced dramatically. Taylor's figures represent the minimum size and mass to sustain a prompt criticality but the duration without tamper or neutron reflection would be short. The slope of exponential growth, estimated number of fissions, and specific fissile material are not recorded. Neptunium-236 is fissile and possesses the smallest and lightest critical mass, but isolation of the specific radionuclide makes it an impractical choice. Several other novel fissile materials are known, but U-235 and Pu-239 are the only practical options although two US tests using U-233 (critical mass some 32% less than U235) have taken place.
Carey Sublette stated that neither the United States nor the Soviet Union have ever made public the existence or development of weapons small enough to fit into a normal-sized suitcase or briefcase. The W48 however, does fit the criteria of small, easily disguised, and portable; but its explosive yield was extremely small for a nuclear weapon.In the mid-1970s, debate shifted from the possibility of developing such a device for the military to concerns over its possible use in nuclear terrorism. The concept became a staple of the spy thriller genre in the later Cold War era.

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