What is nuclear fission?

Nuclear fission is a reaction where an atom's nucleus splits into smaller nuclei, releasing a massive amount of energy, neutrons, and gamma rays. Discovered in late 1938 by Otto Hahn, Fritz Strassmann, Lise Meitner, and Otto Robert Frisch, the process forms the basis for both nuclear power generation and nuclear weapons. While typically induced by neutrons in heavy elements like uranium, it can also occur spontaneously through radioactive decay.

What we know

• Nuclear fission is a reaction in which an atomic nucleus splits into two or more smaller nuclei, often producing neutrons, gamma rays, and a large amount of energy. [1, 2]
• The reaction was discovered by Otto Hahn and Fritz Strassmann, with theoretical explanation provided by Lise Meitner and Otto Robert Frisch. [2]
• Fissionable nuclides primarily split via fast neutrons, whereas fissile nuclides like U-233, U-235, and Pu-239 easily split using slow thermal neutrons. [2]
• Spontaneous fission is a form of radioactive decay where a heavy nucleus splits without an inciting particle, serving as a practical limit for superheavy elements. [2, 3]

Where to go next

• whoWho discovered nuclear fission?
• a case in pointHow do natural nuclear fission reactors form?
• how it workedHow does spontaneous fission limit superheavy elements?
• compared withWhat is the difference between nuclear fission and nuclear fusion?
• what followedHow do pure fission weapons work?
• an unexpected connectionHow did ancient Earth naturally run nuclear reactors?Natural self-sustaining nuclear fission reactors formed spontaneously through geological processes in uranium deposits approximately 1.7 billion years ago.

Sources

• [1]nuclear fission (Wikidata Q11429) · CC0 1.0
• [2]Nuclear fission · CC BY-SA 4.0
• [3]Spontaneous fission · CC BY-SA 4.0
• [4]Natural nuclear fission reactor · CC BY-SA 4.0
• [5]Nuclear weapon design · CC BY-SA 4.0