Techniques are developed for the solidification of radioactive wastes in concrete. Included are the sources, storage, volume reduction, and solidification of liquid wastes at Brookhaven National Laboratory using the cement-vermiculite process, as well as solid waste treatment, shipping containers, and off-site shipments of solid wastes. The properties of low-heat-generating high-level wastes, simulating those in storage at the Savannah River Plant, solidified in concrete were determined. Polymer impregnation was found to further decrease the leachability and improve the durability of these concrete waste forms.