thorium-232
Quick Summary
Thorium-232 is a radioactive isotope of the chemical element thorium, with atomic number 90. It is the most abundant naturally occurring isotope of thorium and has a very long half-life of 1.40 × 1010 years. Thorium-232 is the parent of the thorium radioactive decay series.1
This isotope is significant because it can be used in breeder reactors. When thorium-232 captures slow-moving neutrons, it decays into uranium-233, which is a fissionable material. This process is important for extending the supply of fissionable materials for nuclear power. Thorium itself is a silvery-white metal that turns gray or black when exposed to air and is more abundant than uranium in Earth's crust.12
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rockRadioactive heat generation…important are uranium-235, uranium-238, and thorium-232—and a few with a lower atomic number, such as potassium-40.
Read More…important are uranium-235, uranium-238, and thorium-232—and a few with a lower atomic number, such as potassium-40.
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nuclear reactorFissile and fertile materialsWhen a nucleus of thorium-232 absorbs, or “captures,” a neutron, it becomes thorium-233, whose half-life is approximately 21.83 minutes. After that time the nuclide decays through electron emission to protactinium-233, whose half-life is 26.967 days. The protactinium-233 nuclide in turn decays through electron emission to yield uranium-233.
Read MoreWhen a nucleus of thorium-232 absorbs, or “captures,” a neutron, it becomes thorium-233, whose half-life is approximately 21.83 minutes. After that time the nuclide decays through electron emission to protactinium-233, whose half-life is 26.967 days. The protactinium-233 nuclide in turn decays through electron emission to yield uranium-233.
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