Thorium-232
| General | |
|---|---|
| Symbol | 232Th |
| Names | thorium-232 |
| Protons (Z) | 90 |
| Neutrons (N) | 142 |
| Nuclide data | |
| Natural abundance | 99.98% |
| Half-life (t1/2) | 1.405×1010 years |
| Isotope mass | 232.0380536 Da |
| Spin | 0+ |
| Parent isotopes | 236U (α) 232Ac (β−) |
| Decay products | 228Ra |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| alpha decay | 4.0816 |
| Isotopes of thorium Complete table of nuclides | |
Thorium-232 (232
Th) is the main naturally occurring isotope of thorium, with a relative abundance of 99.98%. It has a half life of 14.05 billion years, which makes it the longest-lived isotope of thorium. It decays by alpha decay to radium-228; its decay chain terminates at stable lead-208.
Thorium-232 is a fertile material; it can capture a neutron to form thorium-233, which subsequently undergoes two successive beta decays to uranium-233, which is fissile. As such, it has been used in the thorium fuel cycle in nuclear reactors; various prototype thorium-fueled reactors have been designed. However, as of 2024, thorium fuel has not been widely adopted for commercial-scale nuclear power.