Leaching tests on bituminized ion-exchange resins from Olkiluoto power plant were made according to ISO/DIS 6961 in deionized water and groundwater. Simulated waste products including Cs and Sr were leached in cement water. A clear difference is seen between the water types. With cobalt in granular resins the leach rate in groundwater is three orders of magnitude higher than in deionized water, the latter being in the order of 10–15 m/s.
The bituminized cation exchanger is still operating and changing ions with the surrounding water. Bitumen provides a hindering diffusion barrier.
Bituminized resin absorbs water from the surroundings and the weight (and volume) of the product increases 10–80 % in 898 days compared to the original value. The weight increase is slower with bituminized powdered resins than with granular resins.
Due to differencies in densities between bitumen and both anion and cation ion-exchangers, a distinct sedimentation effect of granular mixed bed exchangers is observed. The cation exchanger is separated on the bottom of the 200 1 drum while the anion exchanger is separated in the upper part of the drum.