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How is plutonium-239 produced from uranium-238 in a reactor?
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nuclear fission
Italian-born physicist Enrico Fermi explaining a problem in physics, c. 1950. He was awarded the 1938 Nobel Prize for Physics.
In a nuclear reactor, plutonium-239 is produced from uranium-238 through a process of neutron capture followed by radioactive decay.12
The transformation occurs in the following steps:
- Neutron Capture: A nucleus of uranium-238 absorbs a neutron, becoming the isotope uranium-239.12
- First Beta Decay: Uranium-239 is unstable and undergoes beta decay (emitting a beta particle) with a half-life of approximately 23.5 minutes to become neptunium-239.12
- Second Beta Decay: Neptunium-239 subsequently undergoes further beta decay with a half-life of about 2.356 days to yield plutonium-239.12
This process allows reactors to utilize fertile materials like uranium-238, which accounts for the vast majority of naturally occurring uranium. Once produced, the plutonium can be recovered from irradiated fuel through the plutonium-uranium extraction (PUREX) process for use as nuclear fuel or other applications.132