nuclear club

very little that is radioactive, the concept of a "clean" bomb has resulted: one having a small atomic trigger, a less fissionable tamper, and therefore less radioactive fallout.

at its center is an atomic bomb; surrounding it is a layer of lithium deuteride (a compound of lithium and deuterium, the isotope of hydrogen with mass number 2);

around it is a tamper, a thick outer layer, frequently of fissionable material, that holds the contents together in order to obtain a larger explosion.

1952 at Enewetak by the United States

neutron bomb, which has a minimum trigger and a nonfissionable tamper; it produces blast effects and a hail of lethal neutrons but almost no radioactive fallout and little long-term contamination. This theoretically would cause minimal physical damage to buildings and equipment but kill most living things.

cobalt bomb is, on the contrary, a radioactively "dirty" bomb having a cobalt tamper. Instead of generating additional explosive force from fission of the uranium, the cobalt is transmuted into cobalt-60

creates an extremely hot zone near its center. In this zone, because of the high temperature, nearly all of the matter present is vaporized to form a gas at extremely high pressure.