a nuclear reactor that produces more fuel than it consumes and that derives most of its energy from nuclear fission initiated by neutrons that have not slowed down to the thermal range, tuumareaktor, mis toodab rohkem kütust kui tarbib ning enamus energiast toodetakse tuumalõhustumise käigus neutronite poolt, mis ei ole aeglustunud soojuslikule tasemele