Plutonium-241

Plutonium-241 (²⁴¹
Pu or 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.

Plutonium-241, ²⁴¹Pu

General
Symbol	241Pu
Names	plutonium-241, 241Pu, Pu-241
Protons (Z)	94
Neutrons (N)	147
Nuclide data
Natural abundance	0 (Artificial)
Half-life (t1/2)	14 years
Isotope mass	241.057 Da
Decay products	241Am 237U
Decay modes
Decay mode	Decay energy (MeV)
β−	0.02078(17)[1]
α	5.055(5)[1]
Isotopes of plutonium Complete table of nuclides

Decay properties

Process of successive neutron capture from ²³⁹Pu through ²⁴⁵Cm, including ²⁴¹Pu.

Plutonium-241 is a beta emitter with a half-life of 14.3 years, corresponding to a decay of about 5% of ²⁴¹Pu nuclei over a one-year period. This decay has a Q-value of 20.78±0.17 keV and a mean of 5.227±0.043 keV, and does not emit gamma rays.^[1] 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 years; ²⁴¹Am is a major contributor to the radioactivity of nuclear waste on a scale of hundreds or 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.^[2]

Plutonium-241 also has a rare alpha decay branch to uranium-237, occurring in about 0.002% of decays. With a Q-value of 5.055±0.005 MeV, it can emit Auger electrons and associated X-rays, unlike the beta-decay process.^[1]

Role in nuclear fuel

Americium has lower valence and lower electronegativity than plutonium, neptunium or uranium, so in most nuclear reprocessing, americium tends to fractionate with the alkaline fission products – lanthanides, strontium, caesium, barium, yttrium – rather than with other actinides. Americium is therefore not recycled into nuclear fuel unless special efforts are made.

In a thermal reactor, ²⁴¹Am captures a neutron to become americium-242, which quickly becomes curium-242 (or, 17.3% of the time, ²⁴²Pu) via beta decay. Both ²⁴²Cm and ²⁴²Pu are much less likely to absorb a neutron, and even less likely to fission; however, ²⁴²Cm is short-lived (half-life 160 days) and almost always undergoes alpha decay to ²³⁸Pu rather than capturing another neutron. In short, ²⁴¹Am needs to absorb two neutrons before again becoming a fissile isotope.

Actinides and fission products by half-life v t e
Actinides[3] by decay chain				Half-life range (a)	Fission products of 235U by yield[4]
4n	4n + 1	4n + 2	4n + 3		4.5–7%	0.04–1.25%	<0.001%
228Ra№				4–6 a		155Euþ
248Bk[5]				> 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 in the range of 100 a–210 ka ...
	241Amƒ		251Cfƒ[6]	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[7]
232Th№		238U№	235Uƒ№	0.7–14.1 Ga
₡,  has thermal neutron capture cross section in the range of 8–50 barns ƒ,  fissile №,  primarily a naturally occurring radioactive material (NORM) þ,  neutron poison (thermal neutron capture cross section greater than 3k barns)