Crystalline ceramics: Waste forms for the disposal of weapons plutonium

At present, there are three seriously considered options for the disposition of excess weapons plutonium: i) incorporation, partial bum-up and direct disposal of MOX-fuel; ii.) vitrification with defense waste and disposal as glass ''logs''; iii) deep borehole disposal [1]. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.