Nuclear Weapon

 

NUCLEAR WEAPON:

A nuclear weapon  is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion reactions .Both bomb types release large quantities of energy from relatively small amounts of matter.

Nuclear weapons are the most dangerous weapons on earth.  One can destroy a whole city, potentially killing millions, and jeopardizing the natural environment and lives of future generations through its long-term catastrophic effects.  The dangers from such weapons arise from their very existence.  Although nuclear weapons have only been used twice in warfare—in the bombings of Hiroshima and Nagasaki in 1945—about 13,400 reportedly remain in our world today and there have been over 2,000 nuclear tests conducted to date.  Disarmament is the best protection against such dangers, but achieving this goal has been a tremendously difficult challenge.

There are two basic types of nuclear weapons: those that derive the majority of their energy from nuclear fission reactions alone, and those that use fission reactions to begin nuclear fusion reactions that produce a large amount of the total energy output.

During fission, the nuclei of certain heavy atoms split into smaller, lighter nuclei, releasing excess energy in the process. This can sometimes occur spontaneously, but can also, in certain nuclei, be induced from outside. A neutron is shot at the nucleus and is absorbed, causing instability and fission. In some elements—such as certain isotopes of uranium and plutonium—the fission process also releases excess neutrons, which can trigger a chain reaction if they’re absorbed by nearby atoms.

Fusion works in reverse: when exposed to extremely high temperatures and pressures, some lightweight nuclei can fuse together to form heavier nuclei, releasing energy in the process.

In modern nuclear weapons, which use both fission and fusion, a single warhead can release more explosive energy in a fraction of a second than all of the weapons used during World War II combined—including Fat Man and Little Boy, the two atom bombs dropped on Japan.