Estimation of radionuclides leaching characteristics in different sized geopolymer waste forms with simulated spent ion-exchange resin

Abstract

This study presents a method to solidify spent ion-exchange resin (IER) in a metakaolin-based geo-polymer and shows results of mechanical strength, immersion, leaching, irradiation, and thermal cycling tests for waste acceptance criteria (WAC) to repository. The geopolymer waste form with 20 wt% of simulated spent IER met the WAC in South Korea (ROK), and the leaching tests of various sized-waste forms up to 15.0 x 30.0 cm and waste loadings up to 20 wt% for 1-5 d and 1-90 d achieved a leach-ability index, L-i > 6. In a leaching test for 5 d, the cumulative fraction leached (CFL) for Cs, which leached the most, was linearly correlated with the square root of leaching time for all waste forms, and L-i increased as the size of the waste form increased. The CFL was also correlated with elapsed time in the 90 d leaching test. The correlations among CFL, time, and volume-to-surface area ratio of waste forms used to estimate the L(i )of Cs of a 200-L sized geopolymer with 15 wt% IER showed the L-i values as 14.73 (5 d) and 17.71 (90 d), respectively, indicating that the large-sized geopolymer waste form met the WAC.(c) 2023 Korean Nuclear Society, Published by Elsevier Korea LLC. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).