The possible transmutation of radioactive waste from nuclear reactors

Abstract

A nuclear reactor power program produces high level long lived radio-active wastes. The high level activity is associated with fusion products, but beyond 400 years the principal waste hazard is from transuranic elements produced in the reactor. Several schemes have been proposed for the transmutation of the problem isotopes into more easily handled isotopes. The neutron flux in a thermal reactor is not high enough to significantly reduce the longer lived fission product isotopes 90Sr and 132Gs, but the transuranic elements can be reduced by recycling through power reactors. The limitation on recycling of the transuranic elements is the separation process to remove trace quantities from the wast stream. In fact reactors the transuranic elements are the principal fuel and fast reactor waste contains only half as much 90Sr as thermal reactors. However, the overall waste hazard is similar to thermal reactors. A sufficiently intense neutron flux for fission product transmutation could perhaps be produced by a spallation reactor driven by a proton linear accelerator or a controlled thermonuclear reactor. However, both concepts are still some years in the future. Transmutation by accelerator sources of protons, electron or gammas tend to require more energy than neutron transmutation.