![]() A solution of Protactinium-231 | |
General | |
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Symbol | 231Pa |
Names | Protactinium-231, 231Pa, Pa-231 |
Protons (Z) | 91 |
Neutrons (N) | 140 |
Nuclide data | |
Natural abundance | 100% |
Half-life (t1/2) | 32600 years[1] |
Isotope mass | 43.9594029[2] Da |
Decay products | 227Ac |
Decay modes | |
Decay mode | Decay energy (MeV) |
Isotopes of protactinium Complete table of nuclides |
Protactinium-231 is the longest-lived isotope of protactinium, with a half-life of 32,760 years. In nature, it is found in trace amounts as part of the actinium series, which starts with the primordial isotope uranium-235; the equilibrium concentration in uranium ore is 46.55 231Pa per million 235U. In nuclear reactors, it is one of the few long-lived radioactive actinides produced as a byproduct of the projected thorium fuel cycle, as a result of (n,2n) reactions where a fast neutron removes a neutron from 232Th or 232U, and can also be destroyed by neutron capture, though the cross section for this reaction is also low.
binding energy: 1759860 keV
beta decay energy: −382 keV
spin: 3/2−
mode of decay: alpha to 227Ac, also others
possible parent nuclides: beta from 231Th, EC from 231U, alpha from 235Np.
References
edit- ^ Audi, G.; Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S. (2017). "The NUBASE2016 evaluation of nuclear properties" (PDF). Chinese Physics C. 41 (3): 030001. Bibcode:2017ChPhC..41c0001A. doi:10.1088/1674-1137/41/3/030001.
- ^ Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
237Np | ||||||||||||||
↑ | ||||||||||||||
231U | ← | 232U | ↔ | 233U | ↔ | 234U | ↔ | 235U | ↔ | 236U | → | 237U | ||
↓ | ↑ | ↑ | ↑ | |||||||||||
231Pa | → | 232Pa | ← | 233Pa | → | 234Pa | ||||||||
↑ | ↑ | |||||||||||||
230Th | → | 231Th | ← | 232Th | → | 233Th | ||||||||
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