Method of the solidification of radioactive waste materials, without boron in the form vitrified using the fly ash and of the radioactive waste materials containing boron as borosilicate glass frits

摘要

Immobilising boron-free radioactive wastes as stable vitrified wastes using borosilicate glass frits such as flyash and radioactive waste containing boron, comprises, when both radioactive wastes are solid: (a) carefully mixing with flyash from a bituminous (or anthracitic) coal-fired power station or such flyash in refined form, silica (SiO2) or sand and sodium nitrate (NaNO3) or sodium carbonate (Na2CO3) to obtain a composition (expressed as oxides) comprising 10-65 wt.% flyash, 0-50 wt.% SiO2, 10-24 wt.% Na2O, 8-20 wt.% boron-containing radioactive waste (expressed as B2O3) and 0-35 wt.% other radioactive wastes (expressed as oxides); and (b) feeding the mixture into a reaction furnace for calcining and melting at 900-1200 deg C, followed by cooling. Also claimed is a process, used when both radioactive wastes are liquid, comprising: (i) drying and/or oxidising each waste and then treating as above; (ii) carefully mixing the other glass frits with the liquid waste in a stirrer vessel to obtain the above composition, introducing the resulting suspension into a reaction furnace, drying and then treating as in the first process; or (iii) drying one of the liquid wastes and/or oxidising both wastes, introducing the residue and the other glass frits into a stirred reactor in the presence of the other liquid waste to obtain the above composition and then treating as in (ii). Further claimed is a process, used when one of the radioactive wastes is liquid, comprising carefully mixing the optionally refined flyash, SiO2 or sand and NaNO3 into the liquid waste to obtain a suspension of the above composition and then treating as in the above process (iii).