Because is only 0.7 percent of naturally occurring uranium, its supply is fairly limited and could well only last for about 50 years of full-scale use. The other 99 percent of the uranium can also be utilized if it is first converted into plutonium by neutron bombardment:
The production of plutonium can be carried out in a breeder reactorA nuclear reactor designed to produce nuclear fuel as it produces energy. which not only produces energyA system's capacity to do work. like other reactors but is designed to allow some of the fast neutrons to bombard the , producing plutonium at the same time. More fuel is then produced than is consumed.
Breeder reactors present additional safety hazards to those already outlined. They operate at higher temperatures and use very reactive liquidA state of matter in which the atomic-scale particles remain close together but are able to change their positions so that the matter takes the shape of its container metals such as sodium in their cooling systems, and so the possibility of a serious accident is higher. In addition the large quantities of plutonium which would be produced in a breeder economy would have to be carefully safeguarded. Plutonium is an α emitter and is very dangerous if taken internally. Its half-lifeIn chemical kinetics, the time it takes for one half of the limiting reactant to be consumed. In nuclear chemistry, the time for half of a sample to undergo radioactive decay. is 24 000 years, and so it will remain in the environment for a long time if dispersed. Moreover, can be separated chemically (not by the much more expensive gaseous diffusionThe spreading of one substance into another (usually involves gases or liquids). used to concentrate ) from fission products and used to make bombs. Such a material will obviously be attractive to terrorist groups, as well as to countries which are not currently capable of producing their own atomic weapons.