What is the principle of nuclear fission?

The principle of nuclear fission involves the splitting of a heavy atomic nucleus into lighter nuclei. This process is critical in nuclear power generation and nuclear weapons, as it releases a significant amount of energy. In fission, when a heavy nucleus, such as Uranium-235 or Plutonium-239, absorbs a neutron, it becomes unstable and splits into two or more smaller nuclei, known as fission fragments. This reaction also releases additional neutrons and energy, often in the form of gamma radiation.

The released neutrons can further induce fission in nearby nuclei, creating a chain reaction which is the basis for nuclear reactors. This differs fundamentally from processes like fusion, where light atomic nuclei combine to form a heavier nucleus. The concept of non-fissile material interacting with neutrons or the absorption of protons by a nucleus is unrelated to the fission process itself, as these involve different nuclear interactions and are not associated with the energy release characteristic of fission.