Fertile material

Fertile material is a term used in nuclear engineering to describe materials that are not themselves fissionable by thermal neutrons, but can be converted into a fissionable material through neutron absorption and subsequent nuclear transformations.

Overview

Fertile materials, as their name suggests, are materials that are capable of becoming more fissile with time, through the process of neutron capture, or neutron activation. This is a key concept in the design of nuclear reactors, particularly breeder reactors.

The two most common examples of fertile materials are thorium-232 and uranium-238. When these fertile materials absorb a neutron, they undergo a series of nuclear reactions, transforming them into the fissile isotopes uranium-233 and plutonium-239, respectively.

Fertile Material in Nuclear Reactors

In a nuclear reactor, fertile material is typically mixed with fissile fuel in the core of the reactor. The fertile material captures neutrons from the fission reaction of the fissile fuel and transforms into more fissile fuel. Over time, the amount of fissile material can actually increase, even as the reactor operates and consumes some of the fissile material. This is the principle behind a breeder reactor.

Thorium-232

Thorium-232 is a fertile material that can absorb a neutron to become thorium-233. Thorium-233 decays into protactinium-233 and then into uranium-233, which is a fissile material.

Uranium-238

Uranium-238 is another fertile material that can absorb a neutron to become uranium-239. Uranium-239 decays into neptunium-239 and then into plutonium-239, which is a fissile material.

See Also

• Nuclear fission
• Nuclear reactor
• Breeder reactor
• Thorium fuel cycle
• Uranium-238
• Plutonium-239

References

Fertile material Resources
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