SOLIDIFICATION OF SPENT ION-EXCHANGE RESIN USING NEW CEMENTITIOUS MATERIAL .2. IMPROVEMENT OF RESIN CONTENT BY FIBER REINFORCED CEMENT

When using cement solidification for spent ion-exchange resin, resin content in the waste form is typically controlled below 20 vol%. This is because the waste forms crack and deteriorate in water at higher resin contents. The deterioration mechanism and its preventive measures were investigated in this study. Swelling pressure of the resin was experimentally measured for various waste forms. The resin in the waste form tended to swell under a water immersion condition and tensile stress was exerted on the cement matrix. The stress value changed in the region of 1.5 approximately 5.5 MPa depending on such factors as resin content and its type. The waste form was deteriorated in water when the tensile stress was higher than the tensile strength of the cement. These results suggested that the deterioration could be prevented by increasing the tensile strength of cement. A fiber reinforced cement was developed for which tensile strength was almost doubled (approximately 7 MPa) by adding 10 wt% steel fiber to the cement. This prevented deterioration and allowed the resin content to be increased from 20 to 42 vol%.