Published online by Cambridge University Press: 21 March 2011
Crystalline ceramic materials based on the cubic zirconia structure have been proposed as candidate waste forms for the immobilization of weapons grade Pu and other actinides. To evaluate a resistance of these materials to self-irradiation for extended period of time, polycrystalline samples of gadolinia-stabilized cubic zirconia, (Zr,Gd,Pu)O2, doped with approximately 10 wt.% 238Pu were synthesized and characterized. Ceramic synthesis was done by sintering in air at 1500°C for 4 hours using starting precursor materials based on coprecipitated and then calcined oxalates of Zr, Gd, Pu. No differences were observed among the zirconia X-ray diffraction patterns that were obtained immediately after ceramic synthesis, or at 88 and 201 days later. MCC-1 leach tests were performed on ceramic specimens in deionized water at 90°C for 28 days. It was found that without correction for ceramic porosity the initial Pu mass loss (NL) was 0.04 g/m2. This increased to 0.35 and 0.37 g/m2, respectively, 180 and 260 days later. Results obtained allow us to confirm that actinide-doped cubic zirconia is highly resistant to accelerated self-irradiation and therefore, is an efficient material for actinide immobilization in deep geological repositories.