Synroc immobilization of high level waste (HLW) bearing a high content of sodium

Synroc has been regarded as the second generation of high level waste (HLW) forms in the world. By isomorphous replacement most waste elements in HLW can be incorporated into the Synroc phases. The leach resistance and physical properties of Synroc are suitable for HLW immobilization. In general, sodium is not suitable for incorporation into Synroc. Two formulations, (Na0.5Nd0.5)TiO3, perovskite type and Na2(AlFe)2Ti6O16, freudenbergite type were developed to immobilize higher content of Na2O up to 5.7 and 5.0 wt%, respectively. The present study greatly improved the sodium immobilization ability of Synroc.