Maximum cladding temperatures in heterogeneous liquid-metal fast breeder reactors (LMFBRs) can be reduced if the flow allocation between core and blanket assemblies is continuously varied during burnup. An analytical model has been developed that optimizes the time variation of the flow such that the reduction in maximum cladding temperatures is maximized. In addition, the concept of continuously varying the flow allocation between core and blanket assemblies has been evaluated for different fuel management schemes in a low sodium void reactivity 3000-MW heterogeneous LMFBR. This evaluation shows that (a) the reduction in maximum cladding midwall temperatures is small (~10°C) if the reactor is partially refueled at the end of each burnup cycle (cycle length of one year), and (b) this reduction is increased to 20°C if a straight burn fuel scheme is used with a core and internal blanket fuel residence time of two years.