Study On Large Volume Poured Cement Based Low And Intermediate Level Radioactive Waste And Mechanism Of Cs Solidified

High level radioactive waste liquid is transformed to low and middle level by processes of extraction and ion exchange which could get rid of transuranic elements and Sr and Cs. Though the cementitious solidification methods not only own much of characteristics such as easy gained raw material, simplified solidification technics, low cost, hut have been widely applied, it is facing a difficult problem lor science researchers how to enhance the ability of retaining Cs+, Sr2+ in our coast areas. The researching content of this dissertation is choosing the appropriate prescription of large volume poured alkali-activated slag cement based simulated non low and intermediate level radioactive waste form, so the leach rate of Cs+ , Sr2+ could be lowered. Further more, the existing format in waste form is studied which is helpful to explain the mechanism of Cs+ solidified.With the necessary preprocess denitric, it could be solidified directly by the alkali-activated-slag-cement(AASC). In view of the characteristics of the liquid and the demands of its relevant solidification form properties, the radioactive element ions' leach rates are above all researched, so the investigative way of increasing zeolite content in the cementiteous material so as to enhancing the ability of absorption ions of Cs+, Sr2+ and lowering their leaching rales.Experimental results show that with the appropriate inspiring solvent and the addictive such as the water reducer being selected, and also by the right method of the solidified molding, the AASC waste form with containing 80% of zeolite in its cementitious material could not only poses worthiness of the 28th day's compressive strength, but also its Cs+, Sr2+ leaching rates lowered as well as their other properties coincide with the guideline index. The detailed data are shown as follows:Simulated non a low and intermediate level radioactive waste was solidified in large volume poured alkali-activated slag cement with high content of zeolite. The solidified form with its load of 20% nitrate and water-solid ratio of 0.34 not onlypossesses excellent flowability and workability but have 10.3 MPa of compressive strength. In deionized water, the leach rates of Cs+, Sr2+ in 42nd day were only 2.5 × 10-5 and 1.3 × 10-6 cm -d-1 (GB7023-86, 25℃ ), 0.7% and 0.2% cumulative leach percentage in altering. The relevancies in 28 days reached 3.1 × 10-4 and 2.2× 10-5 g 'cm-2 -d-1 at 90℃ or 5.6× 10-4 and 3.0× 10-5 g -cm-2 'd-1 at 150℃(MCC-1P),and 3.5%, 0.2% or 6.2%, 0.3% respectively. They were not changed more in salt solution. It shows that this kind of solidified form has strong ability retaining Cs+ , Sr2+. The other properties coincide with request of the large volume poured cement.Based on studying leaching property by the modern analysis technologies of XRD,SEM-EDS, AAS, three kinds of retaining Cs+ action in zeolite added alkali activated slag cement radioactive waste form have been not only deduced, but also the physical model of Cs+ solidified be founded. Further more, it is the solidification mechanism of Cs+ which could give a reasonable explain on the Cs+ leaching behaviors of the solidification waste form.