Brutreaktor

A Brutreaktor, or breeder reactor, is a type of nuclear reactor designed to generate more fissile material than it consumes. This is achieved by converting fertile isotopes such as uranium-238 or thorium-232 into fissile isotopes like plutonium-239 or uranium-233 through neutron capture and subsequent beta decay. Breeding requires a favorable neutron economy and is most readily achieved in a fast neutron spectrum, though certain thermal systems have been proposed.

In practice, breeders operate with a closed fuel cycle: spent fuel is reprocessed to separate the new fissile material for reuse as fuel. Many fast breeders use liquid metal coolants, such as sodium or lead, to maintain a fast spectrum and compact core. The key metric is the breeding ratio, the number of fissile atoms produced per fissile atom consumed; a ratio above one indicates net material production.

History and examples: The concept emerged in the mid-20th century. Experimental and commercial units include the United States' Experimental Breeder Reactor I, France's Phénix and Superphénix, and Russia's BN series reactors (BN-600, BN-800). Several other designs have been built or proposed in Europe and Asia. As of the early 2020s, only a small number of breeders remained in operation, with many projects discontinued or delayed due to cost, safety, and proliferation concerns.

Advantages and challenges: Breeder reactors can extend nuclear fuel resources by using abundant fertile material and potentially reduce long-lived waste through transmutation. They face challenges such as higher capital costs, complex operation, safety concerns associated with fast reactors and liquid metal coolants, and proliferation risks from plutonium separation. Research continues into advanced designs, including thorium-based and molten salt options, and into methods of closing the fuel cycle more safely.