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FISSION PROCESS CRITICAL MASS

The fission process is initiated when a neutron strikes the isotope’s nucleus and causes it to split into two separate nuclei. Each of these two halves contains half as many protons and neutrons of the original nucleus, and a great amount of thermal energy, gamma rays, and two or more neutrons are released. The neutrons collide with the nuclei, creating further fission processes. Even more neutrons are emitted, and other nuclei are split. This chain reaction will ultimately consume all of the material in the atom, and a massive explosion results.

Uranium-235 and plutonium-239 are not the only isotopes capable of producing these chain reactions, but fission commences more readily in these isotopes than in others, and they emit more neutrons in each stage of the process. A small amount of uranium-235 (for example, one pound) cannot undergo a chain reaction because the neutrons that may be released in the process are likely to escape before they strike other nuclei. If the amount of radioactive material is larger, the chances that a released neutron will strike a nucleus are increased, since the number and density of nuclei is also increased.

The Little Boy and Fat Man bombs employed fission to create the enormous amounts of destructive energy. Also known as atomic bombs, fission weapons involve the splitting of a heavy radioactive element’s nucleus. In the case of Little Boy, the element involved was the isotope uranium-235, while Fat Man used another isotope, plutonium-239.

Fission Weapons

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