IMMOBILIZATION OF SIMULATED ACTINIDES IN PYROCHLORE-RICH SYNROC

Pyrochlore rich Synroc samples with different simulated actinide waste loading(37 %～50 %) are fabricated and tested. The XRD and SEM/EDS analysis show that the major phase is well concordant with the formulation design. The samples have good physical properties: density(>5.1 g/cm 3),open porosity(<0.2%)and vickers hardness(>1 000 kg/mm 2). The samples leach rates are in the order 10 -3 (for Ca),10 -6 (for Ti) and 10 -7 (for Nd and U) g/(m 2·d), better than that of the Zirconolite rich Synroc samples. Thus the Pyrochlore rich Synroc offers a suitable host to incorporate actinides. It is a durable material even under hydrothermal condition with high waste loading and density, which is in favor for final geological disposal.