Comparative leaching behavior of SYNROC B and a borosilicate glass

Specimens of SYNROC B were fabricated under a variety of conditions and doped with simulated radwaste species. Two of the component phases of SYNROC B, perovskite and zirconolite, doped with strontium and uranium, respectively, were also fabricated. All specimens were carefully characterized for both phase content and dopant partitioning via x-ray diffraction and electron beam microanalysis techniques. These specimens were then subjected to neutron activation and leached, and the leachant was analyzed by gamma spectrum analysis. All data were compared with similar analyses of Pacific Northwest Laboratory glass 76-68, a borosilicate glass. It was found that both perovskite and properly prepared SYNROC B leach at about the same rate as the borosilicate glass, while zirconolite appears to be at least an order of magnitude more resistant to leaching. When SYNROC is prepared under undesirable conditions and contains Ba2Ti9O20, cesium leach rates are one to three orders of magnitude higher than in the correctly composed SYNROC B