Although the first breeder reactor experiments were performed in the United States, leadership in developing this technology has been assumed by Europe and Russia. In the whole world, only several breeder fission plants are operational, and the de­velopment of additional breeder reactors will be a slow process, as many technical and safety problems have yet to be resolved. For example, for reasons too complex to consider here, breeder fission reactors use liquid sodium (a highly reactive metal that could easily corrode pipes and cause leaks) as a coolant, rather than water. Should a leak cause the loss of some of the liquid sodium coolant, the tem­perature within the reactor might get high enough to cause an uncontrolled nuclear fission reaction— that is, a small nuclear explosion. The force of this explosion would almost certainly rip open the con­tainment building, releasing radioactive materials into the atmosphere.

    Public and governmental distrust of breeder reactor is greater than misgivings about conventional fission, because plutonium is used not only in breeder nuclear fusion, but also in nuclear

weapons. Getting the public to support construction of nuclear breeder reactors is currently very difficult in Europe and virtually impossible in the United States.