[en] Simulated high level radioactive waste (HLW) similar to these generated from nuclear fuel reprocessing has been incorporated in a very stable, inert, crystalline, durable solid waste form. This solid form is an assemblage of three mineral phases, Hollandite (BaAl₂Ti₆O₁₆), Perovskite (CaTiO₃) and Zirconolite (CaZrTi₂O₇). these phases are known for their high thermodynamic stability, their compatibility with each other, and their ability to incorporate a wide range of HLW ions in their crystal lattice structures. A subsolidus sintering technique has been developed in this research as an alternative method for processing which has sown its advantages over a previously proposed hot pressing technique particularly for remote operation in high gamma radiation fields. The sintered SYNROC-B ceramic produced by this technique has fine-grained micro-structure (approx. 1 to 3 μm grain diameter) with uniform distribution for HLW ions in a locally heterogeneous three-phase system. Phase identification has been carried out by x-ray diffraction techniques