Hot Isostatically Pressed Zirconolite Wasteforms for Actinide Immobilisation

Abstract In order to demonstrate the deployment of Hot Isostatic Pressing (HIP) for the immobilisation of Pu stocks and residues, a series of active and inactive zirconolite formulations have been processed and characterised. In this instance, Ce, U, and Th have been applied as chemical surrogates for Pu 4+ . A range of formulations targeting isovalent Zr 4+ site substitution ( i.e. to simulate CaZr 1-x Pu x Ti 2 O 7 ) have been processed by HIP and characterised by powder X-ray diffraction, and scanning electron microscopy, in order to determine surrogate partitioning between the host zirconolite phase, and accessory phases that may have formed during the HIP process.