Title: Plutonium - Wikipedia
Headings: Plutonium
Plutonium
Contents
Characteristics
Physical properties
Allotropes
Nuclear fission
Isotopes and nucleosynthesis
Decay heat and fission properties
Decay heat of plutonium isotopes
Compounds and chemistry
Electronic structure
Alloys
Occurrence
History
Discovery
Early research
Production during the Manhattan Project
Trinity and Fat Man atomic bombs
Cold War use and waste
Medical experimentation
Applications
Explosives
Mixed oxide fuel
Power and heat source
Precautions
Toxicity
Marine toxicity
Criticality potential
Flammability
Transportation
Land and sea
Air
Notes
Footnotes
Citations
References
External links

Content: Trace quantities arise in natural uranium-238 deposits when uranium-238 captures neutrons emitted by decay of other uranium-238 atoms. Plutonium is much more common on Earth since 1945 as a product of neutron capture and beta decay, where some of the neutrons released by the fission process convert uranium-238 nuclei into plutonium-239. The quantity of isotopes in the decay chains at a certain time are calculated with the Bateman equation . Both plutonium-239 and plutonium-241 are fissile, meaning that they can sustain a nuclear chain reaction, leading to applications in nuclear weapons and nuclear reactors. Plutonium-240 exhibits a high rate of spontaneous fission, raising the neutron flux of any sample containing it. The presence of plutonium-240 limits a plutonium sample's usability for weapons or its quality as reactor fuel, and the percentage of plutonium-240 determines its grade ( weapons-grade, fuel-grade, or reactor-grade). Plutonium-238 has a half-life of 87.7 years and emits alpha particles. It is a heat source in radioisotope thermoelectric generators, which are used to power some spacecraft. Plutonium isotopes are expensive and inconvenient to separate, so particular isotopes are usually manufactured in specialized reactors. Producing plutonium in useful quantities for the first time was a major part of the Manhattan Project during World War II that developed the first atomic bombs.