Thermodynamics, kinetics, and mechanics of cesium sorption in cement paste: A multiscale assessment
Name
PhysRevMaterials.2.053608.pdf
Size
1.59 MB
Format
Adobe PDF
Checksum (MD5)
495e1cf0790ff4bd255c4fe726d9b112
Author(s)
Arayro, Jack
Béland, Laurent Karim
Dufresne, Alice
Zhou, Tingtao
Ioannidou, Aikaterini
Ulm, Josef-Franz
Pellenq, Roland Jm
Date Issued
May 2018
Journal
Physical Review Materials
Publisher
American Physical Society
Citation
Arayro, Jack et al. "Thermodynamics, kinetics, and mechanics of cesium sorption in cement paste: A multiscale assessment." Physical Review Materials 2, 5 (May 2018): 053608 © 2018 American Physical Society
Version
Final published version
Abstract
Cesium-137 is a common radioactive byproduct found in nuclear spent fuel. Given its 30 year half life, its interactions with potential storage materials—such as cement paste—is of crucial importance. In this paper, simulations are used to establish the interaction of calcium silicate hydrates (C-S-H)—the main binding phase of cement paste—with Cs at the nano- and mesoscale. Different C-S-H compositions are explored, including a range of Ca/Si ratios from 1.0 to 2.0. These calculations are based on a set of 150 atomistic models, which qualitatively and quantitatively reproduce a number of experimentally measured features of C-S-H—within limits intrinsic to the approximations imposed by classical molecular dynamics and the steps followed when building the models. A procedure where hydrated Ca[superscript 2+] ions are swapped for Cs[superscript 1+] ions shows that Cs adsorption in the C-S-H interlayer is preferred to Cs adsorption at the nanopore surface when Cs concentrations are lower than 0.19 Mol/kg. Interlayer sorption decreases as the Ca/Si ratio increases. The activation relaxation technique nouveau is used to access timescales out of the reach of traditional molecular dynamics (MD). It indicates that characteristic diffusion time for Cs[superscript 1+] in the C-S-H interlayer is on the order of a few hours. Cs uptake in the interlayer has little impact on the elastic response of C-S-H. It leads to swelling of the C-S-H grains, but mesoscale calculations that access length scales out of the range of MD indicate that this leads to practically negligible expansive pressures for Cs concentrations relevant to nuclear waste repositories.
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
Massachusetts Institute of Technology. Department of Physics
MIT Energy Initiative
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DOI of Published Version
https://doi.org/10.1103/PhysRevMaterials.2.053608
