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° and 150°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 highlevel 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 La2Zr2O7 waste form are less than about 10−4 g·m−2·d−1 at 150°C for a leach time of 32 d in deionized water.