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Plutonium-241
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| General | |
|---|---|
| Symbol | 241Pu |
| Names | plutonium-241 |
| Protons (Z) | 94 |
| Neutrons (N) | 147 |
| Nuclide data | |
| Natural abundance | 0 (synthetic) |
| Half-life (t1/2) | 14.33 years[1] |
| Isotope mass | 241.056850[2] Da |
| Decay products | 241Am 237U |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| β− | 0.0208[3] |
| α | 5.140[3] |
| Isotopes of plutonium Complete table of nuclides | |
Plutonium-241 (241
Pu, Pu-241) is an isotope of plutonium formed when plutonium-240 captures a neutron. Like some other plutonium isotopes (especially 239Pu), 241Pu is fissile, with a neutron absorption cross section about one-third greater than that of 239Pu, and a similar probability of fissioning on neutron absorption, around 73%. In the non-fission case, neutron capture produces plutonium-242. In general, isotopes with an odd number of neutrons are both more likely to absorb a neutron and more likely to undergo fission on neutron absorption than isotopes with an even number of neutrons.
Decay properties
[edit]
Plutonium-241 is a beta emitter with a half-life of 14.33 years, corresponding to a decay of about 5% of 241Pu nuclei over a one-year period. This decay has a Q-value of only 20.8 keV, and does not emit gamma rays.[3] The longer spent nuclear fuel waits before reprocessing, the more 241Pu decays to americium-241, which is nonfissile (although fissionable by fast neutrons) and an alpha emitter with a half-life of 432.6 years; 241Am, which does emit gamma rays, is a major contributor to the radioactivity of nuclear waste on a scale of hundreds to thousands of years.[citation needed] In its fully ionized state, the beta-decay half-life of 241Pu94+ decreases to 4.2 days, and only bound-state beta decay is possible.[4]
Plutonium-241 also has a rare alpha decay branch to uranium-237, occurring in about 0.0025% of decays. Unlike its usual beta decay, this can emit gamma rays, X-rays, and associated electrons.[1]
| Actinides[5] by decay chain | Half-life range (a) |
Fission products of 235U by yield[6] | ||||||
|---|---|---|---|---|---|---|---|---|
| 4n (Thorium) |
4n + 1 (Neptunium) |
4n + 2 (Radium) |
4n + 3 (Actinium) |
4.5–7% | 0.04–1.25% | <0.001% | ||
| 228Ra№ | 4–6 a | 155Euþ | ||||||
| 248Bk[7] | > 9 a | |||||||
| 244Cmƒ | 241Puƒ | 250Cf | 227Ac№ | 10–29 a | 90Sr | 85Kr | 113mCdþ | |
| 232Uƒ | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs | 151Smþ | 121mSn | ||
| 249Cfƒ | 242mAmƒ | 141–351 a |
No fission products have a half-life | |||||
| 241Amƒ | 251Cfƒ[8] | 430–900 a | ||||||
| 226Ra№ | 247Bk | 1.3–1.6 ka | ||||||
| 240Pu | 229Th | 246Cmƒ | 243Amƒ | 4.7–7.4 ka | ||||
| 245Cmƒ | 250Cm | 8.3–8.5 ka | ||||||
| 239Puƒ | 24.1 ka | |||||||
| 230Th№ | 231Pa№ | 32–76 ka | ||||||
| 236Npƒ | 233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126Sn | |||
| 248Cm | 242Pu | 327–375 ka | 79Se₡ | |||||
| 1.33 Ma | 135Cs₡ | |||||||
| 237Npƒ | 1.61–6.5 Ma | 93Zr | 107Pd | |||||
| 236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
| 244Pu | 80 Ma |
... nor beyond 15.7 Ma[9] | ||||||
| 232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
| ||||||||
References
[edit]- ^ a b Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3) 030001. doi:10.1088/1674-1137/abddae.
- ^ Wang, Meng; Huang, W.J.; Kondev, F.G.; Audi, G.; Naimi, S. (2021). "The AME 2020 atomic mass evaluation (II). Tables, graphs and references*". Chinese Physics C. 45 (3) 030003. doi:10.1088/1674-1137/abddaf.
- ^ a b c Basunia, M. S. (1 August 2006). "Nuclear Data Sheets for A = 237". Nuclear Data Sheets. 107 (8): 2323–2422. doi:10.1016/j.nds.2006.07.001.
- ^ Takahashi, K.; Boyd, R. N.; Mathews, G. J.; Yokoi, K. (1 October 1987). "Bound-state beta decay of highly ionized atoms". Physical Review C. 36 (4): 1522–1528. doi:10.1103/PhysRevC.36.1522.
- ^ Plus radium (element 88). While actually a sub-actinide, it immediately precedes actinium (89) and follows a three-element gap of instability after polonium (84) where no nuclides have half-lives of at least four years (the longest-lived nuclide in the gap is radon-222 with a half life of less than four days). Radium's longest lived isotope, at 1,600 years, thus merits the element's inclusion here.
- ^ Specifically from thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
- ^ Milsted, J.; Friedman, A. M.; Stevens, C. M. (1965). "The alpha half-life of berkelium-247; a new long-lived isomer of berkelium-248". Nuclear Physics. 71 (2): 299. Bibcode:1965NucPh..71..299M. doi:10.1016/0029-5582(65)90719-4.
"The isotopic analyses disclosed a species of mass 248 in constant abundance in three samples analysed over a period of about 10 months. This was ascribed to an isomer of Bk248 with a half-life greater than 9 [years]. No growth of Cf248 was detected, and a lower limit for the β− half-life can be set at about 104 [years]. No alpha activity attributable to the new isomer has been detected; the alpha half-life is probably greater than 300 [years]." - ^ This is the heaviest nuclide with a half-life of at least four years before the "sea of instability".
- ^ Excluding those "classically stable" nuclides with half-lives significantly in excess of 232Th; e.g., while 113mCd has a half-life of only fourteen years, that of 113Cd is eight quadrillion years.