Zirconia ceramics for excess weapons plutonium waste

We synthesized a zirconia (ZrO(2))-based single-phase ceramic containing simulated excess weapons plutonium waste. ZrO(2) has large solubility for other metallic oxides. More than 20 binary systems A(x)O(y)-ZrO(2) have been reported in the literature, including PuO(2), rare-earth oxides, and oxides of metals contained in weapons plutonium wastes, We show that significant amounts of gadolinium (neutron absorber) and yttrium (additional stabilizer of the cubic modification) can be dissolved in ZrO(2), together with plutonium (simulated by Ce(4+), U(4+) or Th(4+)) and impurities (e.g., Ca, Mg, Fe, Si). Sol-gel and powder methods were applied to make homogeneous, single-phase zirconia solid solutions. Pu waste impurities were completely dissolved in the solid solutions. In contrast to other phases, e.g., zirconolite and pyrochlore, zirconia is extremely radiation resistant and does not undergo amorphization. Baddeleyite (ZrO(2)) is suggested as the natural analogue to study long-term radiation resistance and chemical durability of zirconia-based waste forms. (C) 2000 Elsevier Science B.V. All rights reserved.