Neutronics performances were analyzed for a partial-refueling ultra-long-life core (ULLC) using metallic fuel for 1000-MW(electric) liquid-metal fast breeder reactors. Once this core is initially loaded, only fertile materials are needed as core reload fuel for the rest of the reactor lifetime, taking advantage of the superior breeding characteristics of the metallic fuel. The fuel management strategy demonstrates the core concept and establishes relevant performance parameters such as a manageable reactivity swing and flat power distributions over the burnup cycles. The following advantages of this ULLC concept over the nonrefueling ULLC were found: smaller control reactivity requirements over the cycle lower power peaking factor and lower power swings during burnup