Influence of ageing on the effective coefficient of the radionuclides Cs-137 and Co-60 in the system: bitumen-spent ion-exchange resins

A competetive method for the immobilization of low and intermediate level radioactive wastes is bitumenization. In the Institute - Vinca, immobilization has been carried out in order to find bitumen-radioactive waste mixtures which satisfy all the safety recommendations given by the IAEA and IRPA. In the two years of investigation, three types of bitumen were used as immobilization matrices for different weight percentage values of the spent ion-exchange resins. From measurements of the specific physico-chemical characteristics, the best formulation, from the point of view of safety and economics, was chosen. This paper explains the behaviour of the chosen bitumen-radioactive waste formulation in changing the effective coefficient of diffusion of the Cs-137 and Co-60 from the solidified radioactive waste. The results obtained have shown that the formulation is a good choice for the immobilization of radioactive waste materials, e.g. spent ion-exchange resins, in bitumen. (Author)