Nuclear Fission and Fusion - SS2 Physics Lesson Note
Nuclear fission and fusion are two processes involving the release or absorption of energy by manipulating the atomic nuclei of atoms. They are the fundamental processes responsible for the energy production in nuclear power plants and the immense energy output of stars.
Nuclear Fission:
Nuclear fission is the process in which the nucleus of an atom is split into two or more smaller nuclei, accompanied by the release of a large amount of energy. The fission process is typically initiated by bombarding a heavy nucleus, such as uranium-235 or plutonium-239, with a neutron. The resulting nucleus becomes unstable and splits into two or more smaller fragments. In the fission process, additional neutrons are also released, which can go on to initiate a chain reaction by colliding with other heavy nuclei and causing them to undergo fission as well. The energy released in nuclear fission is a result of the conversion of mass into energy, according to Einstein's equation E=mc2. The difference in mass between the original nucleus and the resulting fragments is converted into a large amount of kinetic energy and radiation. The energy released during fission is primarily in the form of the kinetic energy of the fission fragments and a large number of high-energy neutrons.
Nuclear Fusion:
Nuclear fusion is the process in which two or more light atomic nuclei combine to form a heavier nucleus, accompanied by the release of a tremendous amount of energy. Fusion reactions occur at extremely high temperatures and pressures, such as those found in the core of stars, including our Sun. In fusion reactions, light elements such as hydrogen isotopes (deuterium and tritium) are typically involved. These nuclei have positive charges that repel each other, requiring extremely high temperatures and pressures to overcome the electrostatic repulsion and bring the nuclei close enough for the strong nuclear force to bind them together. The fusion process releases a vast amount of energy due to the conversion of mass into energy. The resulting nucleus is slightly less massive than the combined mass of the original nuclei. The energy released in fusion reactions is primarily in the form of high-energy photons (gamma rays) and the kinetic energy of the fusion products (such as helium nuclei). Fusion reactions have the potential to provide a virtually limitless and clean source of energy, as they can utilise abundant fuel sources and produce minimal radioactive waste.
Applications of Nuclear Fission and Fusion:
- Nuclear fission is widely used in nuclear power plants to generate electricity. Controlled fission reactions in nuclear reactors produce heat, which is used to generate steam and drive turbines. Nuclear fission reactions provide a significant portion of the world's electricity supply.
- Nuclear fusion is a field of ongoing research with the goal of achieving controlled fusion reactions on Earth for energy production. Successful fusion reactions would provide a virtually limitless and environmentally friendly source of energy, similar to the processes occurring in the Sun.
- Nuclear fission has also been used in the development of nuclear weapons. Uncontrolled chain reactions of fission reactions release an immense amount of energy in the form of an explosion.
- Both nuclear fission and fusion have important applications in scientific research, such as in the study of fundamental particles and the production of isotopes for medical and industrial purposes.
In summary, nuclear fission involves the splitting of heavy atomic nuclei into smaller fragments, while nuclear fusion involves the combination of light atomic nuclei to form a heavier nucleus. Both processes release a significant amount of energy due to the conversion of mass into energy. Nuclear fission is currently used for electricity generation in nuclear power plants and has been used in the development of nuclear weapons. Nuclear fusion, although still a field of ongoing research, holds the potential for clean and abundant energy production. Understanding and harnessing the power of nuclear fission and fusion have far-reaching implications for energy production, scientific research, and various technological applications.