The plutonium isotopes listed below are “fissionable,” which means that the nuclei can be split into two fragments, called fission products. In addition to being fissionable, plutonium-239 and plutonium-241 are “fissile” – that is, they can be split by neutrons of very low (ideally zero) energy. This means that they can be assembled into a critical mass, and hence can sustain a chain reaction without an external source of neutrons. To help you learn more about the properties of Plutonium, check out this worksheet on Plutonium!
| Pu-238 | Pu-239 | Pu-240 | Pu-241 | Pu-242 | |
|---|---|---|---|---|---|
| Half-life (in years) | 87.74 | 24,110 | 6,537 | 14.4 | 376,000 |
| Specific activity (curies/gram) | 17.3 | 0.063 | 0.23 | 104 | 0.004 |
| Principal decay mode | alpha | alpha | alpha and some spontaneous fission [1] | beta | alpha |
| Decay energy (MeV) | 5.593 | 5.244 | 5.255 | 0.021 | 4.983 |
| Radiological hazards | alpha and weak gamma | alpha and weak gamma | alpha and weak gamma | beta and weak gamma [2] | alpha and weak gamma |
| How isotope is produced | nuclear reactors | nuclear reactors | nuclear reactors | nuclear reactors | nuclear reactors |
| Main uses | Production of thermoelectric power used in nuclear weapons, satallites, and heart pacemakers |
Fissile material for nuclear weapons, and for the production of energy |
none | none | none |
Source: CRC Handbook of Chemistry and Physics, 1990-1991. Various sources give
slightly different figures for half-lives and energies.