Synroc Immobilization of Simulated Radioactive Incineration Ash Doped Uranium

The researches on synroc immobilization of simulated radioactive incineration ash (SRIA) doped uranium were carried out by solid-state reaction at high temperature, using zirconite, SRIA, CaCO₃, TiO₂ and UO₂ as raw materials. The properties of synroc form were investigated by means of X-ray diffraction analysis, scanning electron microscope analysis and leaching property test. The results indicate that the crystal phases of synroc form sintered in air are zirconolite CaZrTi₂O₇Ca(Zr,U)Ti₂O₇, sphene(CaTiSiO₅), CaTiO₃ and CaUO₄. A part of uranium is solidified in Ca(Zr,U)Ti₂O₇. The more CaZrTi₂O₇ is propitious to solidifying the more uranium in Ca(Zr,U)Ti²O⁷. The unitary uranium leaching rates of synroc form doped SRIA of 60% and UO² of 6.68% are 0.17-2.81 μg/(cm²•d) for 1-35 d and 0.09-0.13 μg/(cm²•d) for 42-192 d.