Leaching of Sr and Cs from geopolymers under radiation environments

The leaching rates of Sr and Cs from geopolymers used to immobilize municipal solid waste incineration ash as a simulated waste were investigated to ensure the stability to the radiation during long-term storage. The leaching rates were not varied by the dose rates from the natural environment up to 15 Gy/h. However, the temporal variation of the leaching rates exhibited different characteristics depending on the elements. Longer leaching times were required to reach a constant leaching rate for the sample with a larger distribution coefficient. We elucidated the main contributor to leaching by conducting a leaching test on each ingredient. The dose rates investigated in this work correspond to low-level radioactive waste below the approximate boundary level between L2 and L1 in the classification. The production of hydrogen gas by the radiolysis of water and the corrosion of the geopolymers by the effects of radiation were expected, depending on the dose rate of the waste; leaching, however, was not affected by the dose rate.