SOME STUDIES ON THE INCORPORATION OF SIMULATE RADIOACTIVE-WASTES INTO POLYMER MATRIX

Two unsaturated polyester resins were prepared and used with styrene monomer to immobilize simulated spent ion-exchange resin used at Inshas Reactor in Egypt. The composition of the prepared polyesters was studied by means of IR spectroscopy and their physical properties, (i.e., intrinsic viscosity, specific gravity, acid value, and average molecular weight), were determined. The resulting polymer waste-forms were tested to ascertain the properties considered important for radioactive waste management. The items chosen for testing were mechanical strength, radiation and thermal stability, and leachability of radio-nuclides. Factors affecting the mechanical strength of the end products such as styrene content, type and concentration of initiator were investigated. The compressive strength of polyester products burdened with 50 wt% of inactive resin decreased after irradiation to 10(9) rad to about 72% of that none irradiated ones. Below 5 x 10(8) rad these specimens showed improved properties, i.e., higher mechanical strength values owing to further cross-linking of the polymer matrix during irradiation. Thermal properties and oxygen index values illustrated the thermal stability and the flame retardancy of polyester waste-forms. Improved leach resistance was obtained by using deionized water as leaching solution as well as underground water. The leach factors for Cs-137 were always higher than those for Co-60 using both leachants.