The incorporation of transuranic elements in titanate nuclear waste ceramics

The incorporation of actinide elements and their rare earth element analogues in titanate nuclear waste forms are reviewed. New partitioning data are presented for three waste forms containing Purex waste simulant in combination with either NpO2, PuO2 or Am2O3. The greater proportion of transuranics partition between perovskite and zirconolite, while some americium may enter loveringite. Autoradiography revealed clusters of plutonium atoms which have been interpreted as unreacted dioxide or sesquioxide. It is concluded that the solid state behavior of transuranic elements in titanate waste forms is poorly understood; data is certainly inadequate to tailor a ceramic for the incorporation of fast breeder reactor wastes. A number of experiments are proposed that will provide an adequate data base for the formulation and fabrication of transuranic-bearing waste forms. 42 refs., 6 figs., 7 tabs