- 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 ofplutonium with a half-life of 87.7 years and is a very powerfulalpha emitter . Because of its high level of alpha activity, it is used forradioisotope thermoelectric generator s andradioisotope heater unit s. 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 byGlenn Seaborg and associates in 1941 by bombarding uranium-238 withdeuterons . Neptunium-238 is made as an intermediate product, which then decays to form plutonium-238. Plutonium-238 decays toUranium-234 and then further along the radium series toLead-206 .Today, Plutonium 238 is usually prepared by the irradiation of
neptunium 237 , a minor actinide produced innuclear reactor s, that can be recovered fromspent nuclear fuel during reprocessing, or by the irradiation ofamericium in a reactor. In both cases, the targets are subjected to a chemical treatment, including dissolution innitric acid to extract the plutonium-238. A 100kg sample oflight water reactor fuel that has been irradiated for three years contains only about 700 grams ofneptunium 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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