When very large values are obtained for the doubling time of a breeder reactor type, it becomes interesting to see how the finiteness of the lifetime of a reactor plant affects the growth of a breeder population. A possible effect is the time lag between expiration of one plant and start of operation of its replacement plant. An analytical expression for the necessary correction to the compound system doubling time of the reactor population can be derived. Numerical examples show that in realistic cases, correction to the compound system doubling time will be small.