Even proponents of the scheme now acknowledge that a geologic repository would still be needed for much of the residual long-lived waste, including elements like plutonium and neptunium, as well as fission and activation products. In fact, only two of the dozen or so long-lived fission and activation products can be effectively transmuted. Moreover, proliferation dangers would increase due to repeated separation of plutonium and other transuranic materials in reprocessing plants. New reactor types will be necessary and they will create new safety risks. So after hundreds of billions of dollars in investment, the existing problem will not be solved and new ones will be created.
Transmutation requires a nuclear reactor of some type to generate the requisite flux of neutrons.
The transmutation reactions occur when a neutron strikes the nucleus of the atom being transmuted. The nucleus either absorbs the neutron to become a new radionuclide or it fissions. The figure on the easel shows the various stages of the transmutation process and the fate of the different materials. There are a number of different technologies, both for the separation of the radioactive materials and for the reactor. We will be describing some of these technologies later.