Final answer:
Nuclear fission is the splitting of a heavy atomic nucleus into smaller nuclei, releasing energy due to mass conversion into energy. It is essential for nuclear reactors, where it is initiated by neutron bombardment, requires a critical mass, and can create a self-sustaining chain reaction.
Step-by-step explanation:
Nuclear fission is a phenomenon observed in physics where the nucleus of an atom, particularly one of a heavy element, splits into two or more smaller nuclei called fission fragments, accompanied by the release of a significant amount of energy, and often additional free neutrons. This energy release is due to the fact that the mass of the resulting fragments is less than the original mass. In mathematical terms, this mass difference is converted into energy according to Einstein's equation E=mc2.
The process of fission is crucial to the operation of nuclear reactors, which use the energy released to produce electricity. In these reactors, fission is initiated by bombarding a heavy nucleus such as uranium-235 (U-235) or plutonium-239 (Pu-239) with neutrons. When these nuclei capture neutrons, they become unstable and split into two fission fragments and additional neutrons, which can go on to perpetuate the chain reaction. However, for a sustained chain reaction, a critical mass of the fissionable material must be present to ensure that enough neutrons can cause further fissions.
Critical Points of Nuclear Fission:
- Fission releases energy due to mass loss during the conversion of mass into energy.
- Neutron-induced fission is key to maintaining a self-sustained fission reaction.
- A critical mass of the fissionable material is necessary for a chain reaction to sustain itself.
- Fission can lead to supercriticality if more than a critical mass is present.
- Enormous amounts of energy can be unleashed, with practical applications such as electricity generation and in weapons.