I would like to see a nuclear system with pellets of fuel with some enriched uranium in the center. When the enriched uranium reacts, it would create plutonium in the U-238. Then the plutonium would react. All this would happen within the pellet and without removing the pellet from the pebble-bed reactor. That way, there would be less radioactive waste for the energy produced. Also, the plutonium would react without being where it could be stolen for bomb-making; which is one of the concerns of other breeder reactors.