Plutonium-242
General | |
---|---|
Decay mode | Decay energy (MeV) |
Isotopes of plutonium Complete table of nuclides |
Actinides[1] by decay chain | Half-life range (a) |
|||||||
---|---|---|---|---|---|---|---|---|
4n
|
4n + 1
|
4n + 2
|
4n + 3
|
4.5–7% | 0.04–1.25% | <0.001% | ||
228 Ra№
|
4–6 a
|
155 Euþ
|
||||||
244 Cmƒ
|
241Puƒ | 250 Cf
|
227 Ac№
|
10–29 a
|
90Sr | 85Kr | 113m Cdþ
| |
232Uƒ | 238Puƒ | 243 Cmƒ
|
29–97 a
|
137 Cs
|
151 Smþ
|
121m Sn
| ||
248Bk[3]
|
249 Cfƒ
|
242m Amƒ
|
141–351 a |
No fission products have a half-life | ||||
241Amƒ | 251Cfƒ[4]
|
430–900 a | ||||||
226Ra№ | 247 Bk
|
1.3–1.6 ka | ||||||
240Pu | 229 Th
|
246 Cmƒ
|
243 Amƒ
|
4.7–7.4 ka | ||||
245 Cmƒ
|
250 Cm
|
8.3–8.5 ka | ||||||
239Puƒ | 24.1 ka | |||||||
230 Th№
|
231 Pa№
|
32–76 ka | ||||||
236 Npƒ
|
233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126 Sn
| |||
248 Cm
|
242Pu | 327–375 ka | 79Se₡ | |||||
1.53 Ma | 93 Zr
| |||||||
237 Npƒ
|
2.1–6.5 Ma | 135 Cs₡
|
107 Pd
| |||||
236U | 247 Cmƒ
|
15–24 Ma | 129I₡ | |||||
244Pu | 80 Ma |
... nor beyond 15.7 Ma[5] | ||||||
232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
|
Plutonium-242 (242Pu or Pu-242) is one of the isotopes of plutonium, the second longest-lived, with a half-life of 375,000 years. The half-life of 242Pu is about 15 times that of 239Pu; so it is one-fifteenth as radioactive, and not one of the larger contributors to
nuclear waste
radioactivity.
242Pu's gamma ray emissions are also weaker than those of the other isotopes.[6]
It is not
cross section
is also low.
In the nuclear fuel cycle
Plutonium-242 is produced by successive
thermal neutron and about a 1/4 chance of retaining the neutron and becoming the following isotope. The proportion of 242Pu is low at low burnup
but increases nonlinearly.
Plutonium-242 has a particularly low
fast reactor
where it can be fissioned directly. However, 242Pu's low cross section means that relatively little of it will be transmuted during one cycle in a thermal reactor.
Decay
Plutonium-242 mainly decays into
uranium series. Plutonium-242 decays via spontaneous fission in about 5.5 × 10−4% of cases[7]
.
References
- ^ 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.
- thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor.
- .
"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]." - 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.
- ^ "PLUTONIUM ISOTOPIC RESULTS OF KNOWN SAMPLES USING THE SNAP GAMMA SPECTROSCOPY ANALYSIS CODE AND THE ROBWIN SPECTRUM FITTING ROUTINE" (PDF). Archived from the original (PDF) on 2017-08-13. Retrieved 2013-03-15.
- ^ Chart of all nuclei which includes half life and mode of decay