Nuclear fission

In physics, fission is a nuclear process, meaning it occurs in the nucleus of an atom. Fission is when the nucleus splits into two or more smaller nuclei plus some by-products. These by-products include free neutrons and photons (usually gamma rays). Fission releases substantial amounts of energy (the strong nuclear force binding energy).

Related Topics:
Physics - Nuclear - Nucleus - Atom - Neutron - Photon - Gamma rays - Energy - Strong nuclear force - Binding energy

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The use of the energy for peaceful purposes is covered in nuclear power.

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Fission can be induced by several methods, including bombarding the nucleus of a fissile atom with another particle of the correct energy. Usually the other particle is a free neutron moving at the right speed. This free neutron is absorbed by the nucleus, making the nucleus unstable, which then splits into two or more pieces. These pieces are known as fission products and include two smaller nuclei, two or three other free neutrons, and some photons. The process releases a lot of energy compared to chemical reactions; the energy is released in the form of both photon radiation (like gamma rays) and in the kinetic energy (energy of motion) of the nuclei and neutrons. A typical energy released by a fission event is approximately 200 MeV.

Related Topics:
Fissile - Fission product - Chemical reactions - Kinetic energy

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The atomic nuclei released as fission products are of various chemical elements. Which elements are produced is somewhat random, but each nuclei usually ends up with about half the protons and neutrons of the original fissioned atom. Fission products are usually highly radioactive since these other nuclei are not stable isotopes. These isotopes then decay, releasing gamma rays and beta decay radiation. These highly radioactive fission products (or the waste products of their decay, as many of the initial fission products are highly unstable with very short decay times) become the waste of nuclear energy production.

Related Topics:
Chemical element - Proton - Neutron - Radioactive - Isotopes - Beta decay

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An example of a nuclear fission reaction is as follows:

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Neutron + U-235 --> fission products + more neutrons + energy

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