Titanate Ceramics with Pyrochlore Structure as a Matrix for Immobilization of Excess Weapons-Grade Plutonium: II. Hydrolytic Resistance

摘要

Hydrolytic resistance of titanate ceramics of a complex cationic composition with the pyrochlore structure is studied from the standpoint of its use for immobilization of excess weapons-grade plutonium. Data are obtained for both as-prepared ceramics and that transferred into the metamict state under the action of self-irradiation due to the presence of ~(238)Pu (accumulated dose ～160×10~(23) α-events m~(-3)). As-prepared ceramics demonstrate high chemical resistance (low leaching of environmentally significant U and Pu radionuclides). Metamictization results in increasing normalized weight loss (modified MCC-1 test at 90℃ in distilled water) in a three-day leaching experiment: by about two orders of magnitude with respect to U and by over two orders, to Pu. The features of hydrolytic behavior of the complex ceramics studied are discussed.