We have seen above that a large increase of the share of nuclear power in meeting energy needs will most probably require the deployment of a large breeder park. How quickly such a park could be developed will depend on the amount of plutonium available from standard reactor fuel reprocessing, the initial inventory of the breeders, as well as on the doubling time of the breeder park. A relevant study has been made in [30] where the deployment of 3000 PWR reactors in 2030 and an additional 6000 breeders by 2050 was considered. Such a reactor park could stabilize the global temperature, while preserving the possibility of a strong increase of world energy consumption. The question addressed was whether such a deployment is compatible with uranium reserves and doubling times of the breeders.

Two possible breeding cycles were considered: the U-Pu cycle using fast neutron reactors and the Th-U cycle using thermal neutron reactors. In both cases the initial loads are assumed to be mixtures of the fertile element (U or Th) with plutonium taken from the spent fuels of PWR and BWR reactors. It is important to make sure that the amounts of plutonium available would be sufficient to supply all the breeding reactors by 2050.