|About this Abstract
||Materials Science & Technology 2019
||Materials Issues in Nuclear Waste Management
||Modeling of Carbonation Effects in a Cementitious Waste Form under Dry Environmental Conditions
||Peng Zhang, Zhiliang Chen, Andrew C. Garrabrants, Kevin G. Brown, J.C.L. Meeussen, Hans van der Sloot, David S. Kosson
|On-Site Speaker (Planned)
Cast Stone is a cementitious wasteform for low-activity waste that is an option for near-surface disposal in an arid environment. Under aging conditions, gaseous CO2 can react with the material and alter its chemical/physical properties, thus altering the leaching characteristics of radionuclides and other constituents. Arid environment also can draw moisture during aging. The drying process affects the penetration rate of CO2 and the extent of reactions in the wasteform. However, this effect has not been considered in modeling long-term wasteform performance.
A carbonation model is developed for the Cast Stone under dry environmental conditions. The LeachXS™/ORCHESTRA geochemical/reactive transport model is used to model the moisture transport, CO2 diffusion, and the resulting reactions. The carbonation rate as functions of environmental humidity and aging time are predicted and compared with experimental results. The simulation reveals correlation between drying and carbonation and provides a foundation for improved performance assessment of the wasteform.