CHARACTERISTICS ANALYSIS OF SYNROC IMMOBILIZING SIMULATED SODIUM-BEARING HIGH-LEVEL RADIOACTIVE-WASTE

Synroc specimens containing simulated sodium-bearing high-level redioa ctive waste were synthesized by incorporating sodium in (Na0.5Nd0.5)Ti O3-type perovskite. The samples containing 5.7 wt % Na2O (13.0 wt % wa ste oxide accordingly) were cut and machined for physical properties d etermination. XRD analysis, SEM inspection, and a leach test at 90 deg rees C according to the MCC-1 method were also carried out to check th e phase composition, microstructure, and the chemical durability of th e samples. The specimens, which consist mainly of grains of perovskite , zirconolite, hollandite, and freudenbergite, show dense texture and good chemical durability. The leach rates of Na, Sr, and Cs are 3.6 x 10(-2), <1 x 10(-2), and 2.6 x 10(-1) g/m(2) day, respectively, during the 28-day MCC-1 leach test.