A breeder reactor is a type of nuclear reactor designed to generate more fissile material than it consumes. It achieves this by using a combination of uranium or plutonium fuel and a surrounding blanket of fertile material, such as uranium-238 or thorium. When the reactor operates, some of the fertile material is converted into new fissile material, effectively "breeding" fuel for future use. Breeder reactors can help extend the availability of nuclear fuel and reduce waste. They are considered a potential solution for sustainable energy, as they can utilize resources more efficiently than traditional reactors. However, their development and deployment face technical, economic, and safety challenges.