Study On The Solidfication Of Radioactive Wastes With Aluminium Cement Curing Agent

During the development of the nuclear industry,a large amount of radioactive waste liquid will be produced.After the waste liquids are treated with ion exchange,membrane separation and evaporation concentration,secondary pollutants will be generated.How to efficiently treat these wastes restricts the development of the nuclear industry.The cement solidification technology is easy to purchase,low cost,the choice of curing conditions is mild,process equipment is simple,stable performance.So it has a good application prospects in the low-medium level of radioactive wastes solidification.In view of the low waste loading of portland cement,the formulas of sulfoaluminate cement and metakaolin was selected to immobilize the simulated radioactive waste resins.The sulfoaluminate cement could not efficiently immobilized boron-containing steam residue,so this study used sulfoaluminate cement mixed with NaAlO₂ and metakaolin to immobilize boron-containing steaming residue.And the influence of various factors on the performance of the solidified waste forms was studied.This study used sulfoaluminate cement and metakaolin to immobilize the simulated radioactive waste resins.The effects of various components on the setting time,fluidity,compressive strength and center temperature of the solidified waste forms were studied.Combined with XRD and SEM,this study showed that the metakaolin content was5%¹5%,the water-reducing agent content was 1.5%².0%and the waste resins content was 35%⁴0%,the performance of the solidified waste forms was better.The leaching behavior of the nuclide in the solidified waste forms was studied and the result showed that the leaching diffusion could be most effectively controlled with the metakaolin content in the solidified waste forms is 10%and the leaching agent was simulation of groundwater and alkalinity,on this condition,the 42d Cs⁺leaching rate was 6.638×10^-4cm/d、2.881×10^-44 cm/d、6.719×10^-55 cm/d,and satisfied the requirements of GB14569.1-2011.When used sulfoaluminate cement alone to immobilize simulated radioactive boron-containing steaming residue,the wastes could not be disposed.When the B content is 5 g/L,the solidified waste forms was viscous,and when the B content is 10 g/L,the solidified waste forms was liquid.Therefore,this study also used the NaAlO₂.The effects of various components on the setting time,fluidity and compressive strength of the solidified waste forms were studied.Combined with XRD and SEM,this study showed that the content of B in the steamed residue was not to be too high,and the amount of NaAlO₂ was 1%³%and the effects of metakaolin on the properties of the solidified waste forms need to be further studied.The leaching behavior of nuclide in the solidified waste forms was studied.The result showed that the Cs⁺was not easily diffused out of the solidified body when the leaching agent was acidic or simulates groundwater.On this condition,the 42d Cs⁺leaching rate was 3.801×10^-33 cm/d、3.248×10^-3cm/d and satisfied the requirements of GB14569.1-2011.