DURABILITY OF ZIRCONIUM-CONTAINING CERAMIC WASTE FORMS IN WATER

The durability of three ceramic waste forms containing Zr as a constituent is examined at 90-degrees and 150-degrees-C in HCl or deionized water. The three ceramic waste forms examined are: (A) 10-mol%-Y2O3-stabilized ZrO2, (B) La2Zr2O7 with a pyrochlore structure, and (C) CaZrO3 with a perovskite structure. Each form contains an appropriate amount of Ce, Nd, and Sr to simulate the leaching behavior of actinides, lanthanides, and alkaline-earth fission products from high-level nuclear waste. Two forms, (A) 10-mol%-Y2O3-stabilized ZrO2 and (B) La2Zr2O7 with a pyrochlore structure, show excellent durability in HCl and deionized water. For example, leach rates of all constituents in the La2ZrO7 waste form are less than about 10(-4)g.m-2.d-1 at 150-degrees-C for a leach time of 32 d in deionized water.