Durability of an La2Zr2O7 waste form in water

The effects of time, temperature and pH on the leaching rates of an La2Zr2O7 waste form were studied. The leaching rates of each constituent measured in deionized water and an alkaline solution (pH=10) were less than about 10-5g m-2d-1 at 90 °C and were smaller than those in an acid solution (pH=1) by one order of magnitude. It was found that the leaching rate of zirconium obtained after immersion for 34 days decreases with increasing temperature in an acid solution. This exceptional phenomenon is attributed to the formation and decomposition of zirconium complexes with CO32-ligands.