Breeder Reactor
Definition and meaning of Breeder Reactor in chemistry.
A breeder reactor is a nuclear reactor designed to produce more fissile material than it consumes, by converting non-fissile "fertile" isotopes into new fissile fuel while generating power.
In more detail
Breeding occurs when a fertile nuclide absorbs a neutron and, after one or two beta decays, becomes fissile: uranium-238 captures a neutron to form neptunium-239, which decays to plutonium-239, and thorium-232 similarly converts to uranium-233. Achieving a breeding ratio greater than one requires a favorable neutron economy, which is why most breeders use a fast (unmoderated) neutron spectrum, though thermal thorium-cycle designs are also studied. Because natural uranium is over 99% non-fissile uranium-238, breeder reactors can in principle extract far more energy from a given quantity of mined uranium or thorium than conventional reactors.
Key facts
| Field | General Chemistry |
|---|---|
| Key conversion | U-238 → Pu-239 (via Np-239); Th-232 → U-233 |
| Breeding ratio | Greater than 1 (fissile atoms produced per atom consumed) |
| Common designs | Liquid-metal fast breeder reactor (LMFBR); thorium thermal breeder |
A liquid-sodium-cooled fast breeder reactor with a plutonium-239 core surrounded by a uranium-238 "blanket" captures surplus fast neutrons in the blanket, transmuting U-238 into new Pu-239 faster than the core consumes its original Pu-239 fuel.
Frequently asked questions
How is a breeder reactor different from a conventional reactor?
A conventional (burner) reactor has a breeding ratio below 1 and steadily consumes its fissile fuel, while a breeder reactor has a breeding ratio above 1, converting fertile material into new fissile fuel faster than it uses fuel up.
Why use a fast neutron spectrum for breeding?
Fast neutrons cause less parasitic (non-productive) absorption and better preserve the neutron surplus needed for efficient conversion of fertile isotopes like uranium-238 into fissile plutonium-239.