Study On Cementation Formula Ptimization For Simulated Radioactive Waste Resins And The Performances Of Solidified Waste Forms

Radioactive waste is very harmful to the natural environment and human health. Cement solidification is one of the methods of treating radioactive solid wastes. However, there are also some problems in this treatment method, like the curing difficultly and low waste loading. That leads to high volume of waste forms and the high cost of disposal. For solving these problems, this article chose sulphur aluminate cement to solidify waste resin, researched the factors affecting the performance of curing body, optimized the cementation formulas and tested the performances of the optimization formula.First of all, the sulphur aluminate cement, metakaolin and naphthalene series water reducing agent are chosed materials. The research studied various factors which affected the solidification including loading capacity, water-binder ratio, the dosage of metakaolin and water reducing agent UNF-5. The results showed that the amount of metakaolin within 11% of the content was beneficial to the improvement of the compressive strength of the solidified waste forms; Water cement ratio and waste resin loading sharply decreased compressive strength.On the basis of single factor experiment, the curing formula was optimizated by using the method of multi-objective. The optimized formula R1 was obtained, which had 0.445 water cement ratio. And the proportion of waste resin, sulphur aluminate cement, the quality of metakaolin and naphthalene series water reducing agent was 40:55.8:2.2:2.Using the optimization formula R1, solidificated simulated waste resin, and the main performance of the solidified waste forms was investigated. The waste loading of R1 solidified waste forms can reached 64%. The 7 d compressive strength was 13.7 MPa. Solidified waste forms soaked by deionized water of pH of 7 90 d strength was 14.25 MPa, after 5 times after freezing and thawing cycle of strength was 11.42 MPa, the losses were-4.0% and 16.6% respectively. simulated radionuclide in R1 solidified body, in pH 7 under 25 ℃ deionized water in 42 d Cs+ leaching rate was 2.3×10^-4cm/d. Experimental results showed that the main performance of optimized formulation met the GB14569.1-2011. Observed in the SEM images of the solidified waste forms microstructure was that a large number of needle bar and a small amount of amorphous gel particles. In combination with XRD and FTIR, the main mineral phase composition of the solidified body hydration products was ettringite, aluminium glue and a small amount of C- S- H gel.