Nuclear Properties
The nuclear properties of plutonium-239, as well as the ability to produce large amounts of nearly pure Pu-239 more cheaply than highly enriched weapons-grade uranium-235, led to its use in nuclear weapons and nuclear power stations. The fissioning of an atom of uranium-235 in the reactor of a nuclear power plant produces two to three neutrons, and these neutrons can be absorbed by uranium-238 to produce plutonium-239 and other isotopes. Plutonium-239 can also absorb neutrons and fission along with the uranium-235 in a reactor.
Of all the common nuclear fuels, Pu-239 has the smallest critical mass. A spherical untampered critical mass is about 11 kg (24.2 lbs), 10.2 cm (4") in diameter. Using appropriate triggers, neutron reflectors, implosion geometry and tampers, this critical mass can be reduced by more than twofold. This optimization usually requires a large nuclear development organization supported by a sovereign nation.
The fission of one atom of Pu-239 generates 207.1 MeV = 3.318 × 10−11 J, i.e. 19.98 TJ/mol = 83.61 TJ/kg.
| type of radiation source (fission of Pu-239) | Average energy released |
|---|---|
| Instantaneously released energy | |
| Kinetic energy of fission fragments | 175.8 |
| Kinetic energy of prompt neutrons | 5.9 |
| Energy carried by prompt γ-rays | 7.8 |
| Energy from decaying fission products | |
| Energy of β−-particles | 5.3 |
| Energy of anti-neutrinos | 7.1 |
| Energy of delayed γ-rays | 5.2 |
| Sum (total decay energy) | 207.1 |
| Energy released when those prompt neutrons which don't (re)produce fission are captured | 11.5 |
| Energy converted into heat in an operating thermal nuclear reactor (antineutrino energy escapes reactor and does not appear in total heat) | 211.5 |
Read more about this topic: Plutonium-239
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