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Plutonium-239 (239 Pu or Pu-239) is an isotope of plutonium.Plutonium-239 is the primary fissile isotope used for the production of nuclear weapons, although uranium-235 is also used for that purpose.
Weapons-grade plutonium is defined as being predominantly Pu-239, typically about 93% Pu-239. [24] Pu-240 is produced when Pu-239 absorbs an additional neutron and fails to fission. Pu-240 and Pu-239 are not separated by reprocessing. Pu-240 has a high rate of spontaneous fission, which can cause a nuclear weapon to pre-detonate.
Fission product yields by mass for thermal neutron fission of U-235 and Pu-239 (the two typical of current nuclear power reactors) and U-233 (used in the thorium cycle). This page discusses each of the main elements in the mixture of fission products produced by nuclear fission of the common nuclear fuels uranium and plutonium.
Plutonium-239 has half-life 24,100 years. 239 Pu and 241 Pu are fissile; meaning their nuclei can split by being bombarded by slow thermal neutrons, releasing energy, gamma radiation and more neutrons. It can therefore sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors.
Disposal of plutonium and other high-level wastes is a more difficult problem that continues to be a subject of intense debate. As an example, plutonium‑239 has a half-life of 24,100 years, and a decay of ten half-lives is required before a sample is considered to cease its radioactivity.
The Hiroshima bomb, made from highly enriched uranium-235, was about 16 kilotons (equivalent to 16,000 tonnes of TNT), while the Nagasaki bomb, made from plutonium-239, was about 21 kilotons ...
Small traces of plutonium-239, a few parts per trillion, and its decay products are naturally found in some concentrated ores of uranium, [54] such as the natural nuclear fission reactor in Oklo, Gabon. [55] The ratio of plutonium-239 to uranium at the Cigar Lake Mine uranium deposit ranges from 2.4 × 10 −12 to 44 × 10 −12. [56]
Jay Coghlan, director of Nuclear Watch, said plutonium contamination in the heart of Los Alamos is a concern, particularly as the lab — under the direction of Congress, the Energy Department and ...