Abstract
Deep, underground repositories are needed to isolate radioactive waste from the biosphere. Because bentonite is an integral component of many multibarrier repository systems, information on the hydraulic behavior of bentonite is crucial for modeling the long-term viability of such systems. In this paper the hydraulic behavior of bentonite samples was analyzed as a function of aggregate size, and samples were subjected to hydrothermal treatments involving contact with NaCl, KCl, and deionized water. Neutron and X-ray imaging were used to quantify water sorption into packed bentonite samples and bentonite swelling into the water column. The distance between the original clay-water interface and the wetting front was determined as a function of time. Average water uptake exhibited a square-root-of-time dependence in freshly prepared samples, but more variable rates were observed for samples previously in contact with water. The radiography was supported by small-angle neutron scattering analysis and ultra-small-angle neutron scattering analysis of aggregate size distributions and by inelastic neutron scattering to understand the physicochemical environment of the sorbed water. Results showed that hydrothermal treatment with KCl had the greatest effect of increased water transport in the bentonite, possibly as a result of the interaction of K+ with smectite layers in the clay.
| Original language | English |
|---|---|
| Pages (from-to) | 1237-1256 |
| Number of pages | 20 |
| Journal | Nuclear Technology |
| Volume | 207 |
| Issue number | 8 |
| DOIs | |
| State | Published - 2021 |
Funding
Work done by L. M. A., M. C. C., and V. H. D. was supported by the DOE, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. A portion of this research used resources at the HFIR and SNS, DOE Office of Science User Facilities operated by ORNL. Access to the USANS and NG-B 30m SANS was provided by the Center for High Resolution Neutron Scattering, a partnership between the NIST and the National Science Foundation under Agreement No. DMR-1508249. Work done by J. M. L., D. S. H., and D. L. J. was supported by the NIST and the NIST Physical Measurement Laboratory. E. Perfect acknowledges support from the Tom Cronin and Helen Sestak Faculty Achievement award. C. Gagnon and G. Jensen at NCNR assisted with the USANS data analysis. A. D. Vial assisted with some of the preliminary analyses of the neutron radiographic data. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the DOE. The U.S. government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). Work done by L. M. A., M. C. C., and V. H. D. was supported by the DOE, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division. A portion of this research used resources at the HFIR and SNS, DOE Office of Science User Facilities operated by ORNL. Access to the USANS and NG-B 30m SANS was provided by the Center for High Resolution Neutron Scattering, a partnership between the NIST and the National Science Foundation under Agreement No. DMR-1508249. Work done by J. M. L., D. S. H., and D. L. J. was supported by the NIST and the NIST Physical Measurement Laboratory. E. Perfect acknowledges support from the Tom Cronin and Helen Sestak Faculty Achievement award. C. Gagnon and G. Jensen at NCNR assisted with the USANS data analysis. A. D. Vial assisted with some of the preliminary analyses of the neutron radiographic data. This manuscript has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the DOE. The U.S. government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).
| Funders | Funder number |
|---|---|
| DOE Public Access Plan | |
| Office of Basic Energy Sciences | |
| Tom Cronin and Helen Sestak Faculty Achievement | |
| U.S. Government | |
| National Science Foundation | DMR-1508249 |
| U.S. Department of Energy | |
| National Institute of Standards and Technology | |
| Office of Science | |
| Basic Energy Sciences | |
| Oak Ridge National Laboratory | |
| NIST Center for Neutron Research | DE-AC05-00OR22725 |
| Physical Measurement Laboratory | |
| Chemical Sciences, Geosciences, and Biosciences Division |
Keywords
- Water uptake into bentonite
- bentonite swelling
- engineered clay barriers for nuclear fuel disposal
- interfacial energy of water in porous bentonite
- neutron radiography
