The fabrication and properties of Zr-O-F ceramics for the immobilization of Zircaloy nuclear waste

Abstract

The hot-pressing behaviour of hydrated zirconium oxide (with fluoride) derived from Zircaloy nuclear waste is described. The material densifies at relatively low temperatures to give a crystalline ceramic with monoclinic ZrO₂ and an oxyfluoride (Zr₁₀O₁₃F₁₄) as major phases. Doping with the inactive radwaste ions U⁴⁺, Sr²⁺ and Cs⁺ has shown that these should be taken into solid solution in the ceramic at the levels at which they are likely to be present in actual waste. Dissolution tests are described which establish that the ceramics are resistant to attack by water and hence should provide suitable leachresistant hosts for the immobilization of the radwaste ions.