Plutonium-238


Plutonium-238

Infobox isotope
background = #7F7
text_color =


alternate_names =
mass_number = 238
symbol = Pu
num_neutrons = 142
num_protons = 94
abundance =
halflife = 87.7 years
error_halflife =
decay_product =Uranium-234
decay_mass =234
decay_symbol =U
parent = Curium-242
parent_mass = 242
parent_symbol =Cm
parent_decay =a
parent2 =Neptunium-238
parent2_mass =238
parent2_symbol =Np
parent2_decay =b-
parent3 =Americium-238
parent3_mass =238
parent3_symbol = Am
parent3_decay =b+
mass =
spin =0
excess_energy =
error1 =
binding_energy =
error2 =
decay_mode1 =
decay_energy1 =
decay_mode2 =
decay_energy2 =
decay_mode3 =
decay_energy3 =
decay_mode4 =
decay_energy4 =

Plutonium 238, is a radioactive isotope of plutonium with a half-life of 87.7 years and is a very powerful alpha emitter. Because of its high level of alpha activity, it is used for radioisotope thermoelectric generators and radioisotope heater units. The use of plutonium-238 in American and Russian (and old Soviet Union) spacecraft is somewhat controversial.

Plutonium-238 was the first isotope of plutonium to be discovered. It was synthesized by Glenn Seaborg and associates in 1941 by bombarding uranium-238 with deuterons. Neptunium-238 is made as an intermediate product, which then decays to form plutonium-238. Plutonium-238 decays to Uranium-234 and then further along the radium series to Lead-206.

Today, Plutonium 238 is usually prepared by the irradiation of neptunium 237, a minor actinide produced in nuclear reactors, that can be recovered from spent nuclear fuel during reprocessing, or by the irradiation of americium in a reactor. In both cases, the targets are subjected to a chemical treatment, including dissolution in nitric acid to extract the plutonium-238. A 100kg sample of light water reactor fuel that has been irradiated for three years contains only about 700 grams of neptunium 237, and the neptunium must be extracted selectively.

The United States currently has limited facilities to produce plutonium-238. Since 1993, the U.S. has purchased all of the plutonium-238 it has used in space probes from Russia. 16.5 kilograms total have been purchased. [http://nuclear.inl.gov/spacenuclear/docs/final72005faqs.pdf]

Isotope|element=Plutonium
lighter=Plutonium-237
heavier=Plutonium-239
before=Curium-242 (α)
Americium-238 (β+)
Neptunium-238 "'(β-)
after=Uranium-234 "'(α)

ee also

*Atomic battery

References

External links

* [http://sciencereview.berkeley.edu/articles/issue1/elementary.pdf Story of Seaborg's discovery of Pu-238, especially page 34-35.]
* [http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@na+@rel+plutonium,+radioactive NLM Hazardous Substances Databank – Plutonium, Radioactive]


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