SHS/QP Synthesis and Characterization of Ce‐Bearing Zirconolite‐Rich Waste Forms Using MoO3 as the Oxidant

Abstract

In this study, zirconolite (CaZrTi2O7)/Mo composite was rapidly synthesized by self‐propagating high‐temperature plus quick pressing (SHS/QP) technique using MoO3 as the oxidant. As the surrogate of tetravalent actinide nuclides, up to 50 at.% CeO2 (about 17.5 wt% of the raw material) was introduced to substitute the Zr site of zirconolite. Perovskite (CaTiO3) and rutile TiO2 were inevitably produced after the incorporation of CeO2. The raw CeO2 was partially reduced to trivalent state, which promotes the substitution of Ce into the Ca sites of perovskite and zirconolite. The aqueous durability of Ce‐bearing waste form was investigated with normalized leaching rates (42 d) of Ce in moderate value of about 10−2 g m−2 d−1.