Plutonium-242

Plutonium-242, ²⁴²Pu
General
Decay mode	Decay energy (MeV)
	Isotopes of plutonium ; Complete table of nuclides

Plutonium-242 (²⁴²Pu or Pu-242) is the second longest-lived

nuclear waste radioactivity. ²⁴²Pu's gamma ray emissions are also weaker than those of the other isotopes.^[1]

It is not

cross section

is 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.

²⁴²Pu has a particularly low

fast reactor

where it can be fissioned directly. However, ²⁴²Pu's low cross section means that relatively little of it is transmuted during one cycle in a thermal reactor.

Decay

Actinides and fission products by half-life v t e
Actinides^[2] by decay chain				Half-life range (a)	Fission products of ²³⁵U by yield^[3]
4n	4n + 1	4n + 2	4n + 3	Half-life range (a)	4.5–7%	0.04–1.25%	<0.001%
²²⁸Ra^№				4–6 a		¹⁵⁵Eu^þ
248Bk^[4]				> 9 a
²⁴⁴Cm^ƒ	²⁴¹Pu^ƒ	²⁵⁰Cf	²²⁷Ac^№	10–29 a	⁹⁰Sr	⁸⁵Kr	^113mCd^þ
²³²U^ƒ		²³⁸Pu^ƒ	²⁴³Cm^ƒ	29–97 a	¹³⁷Cs	¹⁵¹Sm^þ	^121mSn
	²⁴⁹Cf^ƒ	^242mAm^ƒ		141–351 a	No fission products have a half-life in the range of 100 a–210 ka ...
	²⁴¹Am^ƒ		251Cf^ƒ^[5]	430–900 a
		²²⁶Ra^№	²⁴⁷Bk	1.3–1.6 ka
²⁴⁰Pu	²²⁹Th	²⁴⁶Cm^ƒ	²⁴³Am^ƒ	4.7–7.4 ka
	²⁴⁵Cm^ƒ	²⁵⁰Cm		8.3–8.5 ka
			²³⁹Pu^ƒ	24.1 ka
		²³⁰Th^№	²³¹Pa^№	32–76 ka
²³⁶Np^ƒ	²³³U^ƒ	²³⁴U^№		150–250 ka	⁹⁹Tc^₡	¹²⁶Sn
²⁴⁸Cm		²⁴²Pu		327–375 ka		⁷⁹Se^₡
				1.33 Ma	¹³⁵Cs^₡
	²³⁷Np^ƒ			1.61–6.5 Ma	⁹³Zr	¹⁰⁷Pd
²³⁶U			²⁴⁷Cm^ƒ	15–24 Ma		¹²⁹I^₡
²⁴⁴Pu				80 Ma	... nor beyond 15.7 Ma^[6]
²³²Th^№		²³⁸U^№	²³⁵U^ƒ№	0.7–14.1 Ga	... nor beyond 15.7 Ma^[6]
₡, has thermal fissile №, primarily a naturally occurring radioactive material (NORM) þ, neutron poison (thermal neutron capture cross section greater than 3k barns)

²⁴²Pu

uranium series. ²⁴²Pu decays by spontaneous fission in about 5.5 × 10⁻⁴% of cases.^[7]

References

^ "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.
^ 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
.

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]."

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.

^ Chart of all nuclei which includes half life and mode of decay

v
t
e
Main isotopes of plutonium

²³⁸Pu

²³⁹Pu

²⁴⁰Pu

²⁴¹Pu

²⁴²Pu

²⁴⁴Pu

Retrieved from "https://en.wikipedia.org/w/index.php?title=Plutonium-242&oldid=1255877251"

[1] "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.

[2] 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.

[3] thermal neutron fission of uranium-235, e.g. in a typical nuclear reactor
.

[4] :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]."

[5] sea of instability
".

[6] 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.

[7] Chart of all nuclei which includes half life and mode of decay

[1]

[2]

[3]

[4]

[5]

[6]

[7]