The leaching characteristics of Co-60, Sr-85, and Cs-137 from cemented ion-exchange resin waste forms containing water-extendible polyester resin and Zeolon 900-sodium additives were investigated using three different types of leach tests, that is, the American Nuclear Society (ANS) 16.1, the Battelle Materials Characteristics Centre (MCC) MCC-4S and modified MCC-4S methods. Specimens used in the leach tests were fabricated with cement and ion-exchange bead resins present in the Li+-OH- form. The ion-exchange resins were doped with Co-60, Sr-85, and Cs-137 to simulate the spent resin waste from nuclear power plants.
The presence of Zeolon 900-sodium additive to the waste form formulation provided distinctly improved adsorption for Cs-137 and seemed not to reduce effectively the releases of Co60 and Sr-85. The leaching processes of the three radionuclides from the waste forms were dominated by diffusion. The leaching rates of Co-60 and Sr-85 were both appreciably affected by the leachant flow rate, while Cs-137 was not apparently sensitive. The presence of nonsorbing backfill material was likely to induce the radionuclides to follow longer transport paths than for specimens only in the presence of water. The clinoptilolite selected as a sorbing backfill material did not retard the Co-60 release, but there was strong absorption of Sr-85 and Cs-137 onto the clinoptilolite.