Conceptual Modeling Coupled Thermal-Hydrological-Chemical Processes in Bentonite Buffer for High-Level Nuclear Waste Repository

고준위 방사성폐기물 처분장에서 벤토나이트 완충제에 대한 열-수리-화학 작용 개념 모델링

  • Received : 2015.10.28
  • Accepted : 2015.12.10
  • Published : 2016.03.30


In this study, thermal-hydrological-chemical modeling for the alteration of a bentonite buffer is carried out using a simulation code TOUGHREACT. The modeling results show that the water saturation of bentonite steadily increases and finally the bentonite is fully saturated after 10 years. In addition, the temperature rapidly increases and stabilizes after 0.5 year, exhibiting a constant thermal gradient as a function of distance from the copper tube. The change of thermal-hydrological conditions mainly results in the alteration of anhydrite and calcite. Anhydrite and calcite are dissolved along with the inflow of groundwater. They then tend to precipitate in the vicinity of the copper tube due to its high temperature. This behavior induces a slight decrease in porosity and permeability of bentonite near the copper tube. Furthermore, this study finds that the diffusion coefficient can significantly affect the alteration of anhydrite and calcite, which causes changes in the hydrological properties of bentonite such as porosity and permeability. This study may facilitate the safety assessment of high-level radioactive waste repositories.


Grant : 지중 주입된 이산화탄소 거동 및 누출 모니터링 현장 적용 기술개발

Supported by : 한국지질자원연구원


  1. D. Arcos, J. Bruno, and O. Karnland, "Geochemical model of the granite-bentonite-groundwater interaction at Aspo HRL (LOT experiment)", Applied Clay Science, 23(1-4), 219-228 (2003).
  2. O. Karnland, S. Olsson, and U. Nilsson. Mineralogy and sealing properties of varioius bentonites and smectite- rich caly materials, Svensk karnbranslehantering AB, Technical Report TR-06-30 (2006).
  3. J. Salas, C. Sena, and D. Arcos, "Hydrogeochemical evolution of the bentonite buffer in a KBS-3 repository for radioactive waste. Reactive transport modelling of the LOT A2 experiment", Applied Caly Science, 101, 521-532 (2014).
  4. A. Itala, M. Olin, and J. Lehikoinen, "Lot A2 test, THC modelling of the bentonite buffer", Physics and Chemistry of the Earth, 36(17-18), 1830-1837 (2011).
  5. H.G. Montes, N. Marty, B. Fritz, A. Clement, and N. Michau, "Modelling of long-term diffusion-reaction in a bentonite barrier for radioactive waste confinement", Applied Clay Science, 30(3-4), 181-198 (2005).
  6. P. Wersin, "Geochemical modelling of bentonite porewater in high-level waste repositories", J. of Contaminant Hydrology, 61(1-4), 405-422 (2003).
  7. T. Xu, E. Sonnenthal, N. Spycher, and K. Pruess. TOUGHREACT User's Guide: A Simulation Program for Non-isothermal Multiphase Reactive Geochemical Transport in Variably Saturated Geologic Media, Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (2004).
  8. M.TH. van Genuchten, "A closed-from equation fro predicting the hydraulic conductivity of unsaturated soils", Soil Science Society of America Journal, 44(5), 892-898 (1980).
  9. P.C. Carman, Flow of Gases Through Porous Media, Academic Press, New York City (1956).
  10. O. Karnland, Chemical and mineralogical characterization of the bentonite buffer for the acceptance control procedure in a KBS-3 repositoty, Svensk karnbranslehantering AB, Technical Report TR-10-60 (2010).
  11. B.Y. Choi, G.Y. Kim, Y.K. Koh, S.H. Shin, S.W. Yoo, and D.H. Kim, "Geochemcial characteristics of a LILW repository I. Groundwater", J. of the Korean Radioactive Waste Society, 6(4), 297-306 (2008).
  12. A.C. Lasaga, Kinetic theory in the earth science, Princeton University Press, Princeton, New Jersey (1998).
  13. J.L. Palandi and Y.K. Kharaka, A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modeling, U.S. Geological Survey, Open File Report 2004-1068 (2004).
  14. C. Sena, J. Salas, and D. Arcos, Thermo-hydro-geochemical modelling of the bentonite buffer LOT A2 experiment, Svensk karnbranslehantering AB, Technical Report TR-10-65 (2010).
  15. T.J. Wolery, C.F. Jove-Colon, and R.L. Jareck, Qualification of thermodynamic data for geochemical modeling of mineral-water interactions in dilute systems. ANL-WIS-GS-000003 REV 01, Las Vegas, Nevada (2007).