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Thermal behavior of groundwater-saturated Korean buffer under the elevated temperature conditions: In-situ synchrotron X-ray powder diffraction study for the montmorillonite in Korean bentonite

  • Park, Tae-Jin (Radwaste Disposal Research Division, Korea Atomic Energy Research Institute (KAERI)) ;
  • Seoung, Donghoon (Department of Earth Systems and Environmental Sciences, Chonnam National University)
  • 투고 : 2020.07.09
  • 심사 : 2020.10.14
  • 발행 : 2021.05.25

초록

In most countries, the thermal criteria for the engineered barrier system (EBS) is set to below 100 ℃ due to the possible illitization in the buffer, which will likely be detrimental to the performance and safety of the repository. On the other hand, if the thermal criteria for the EBS increases, the disposal density and the cost-effectiveness for the high-level radioactive wastes will dramatically increase. Thus, fundamentals on the thermal behavior of the buffer under the elevated temperatures is of crucial importance. Yet, the behaviors at the elevated temperatures of the bentonite under groundwater-saturated conditions have not been reported to-date. Here, we have developed an in-situ synchrotron-based method for the thermal behavior study of the buffer under the elevated temperatures (25-250 ℃), investigated dspacings of the montmorillonite in the Korean bentonite (i.e., Ca-type) at dry and KURT (KAERI Underground Research Tunnel) groundwater-saturated conditions (KJ-ii-dry and KJ-ii-wet), and compared the behaviors with that of MX-80 (i.e., Na-type, MX-80-wet). The hydration states analyzed show tri-, bi-, and mono-hydrated at 25, 120, and 250 ℃, respectively for KJ-ii-wet, whereas tri-, mono-, and de-hydrated at 25, 150, and 250 ℃, respectively for MX-80-wet. The Korean bentonite starts losing the interlayered water at lower temperatures; however, holds them better at higher temperatures as compared with MX-80.

키워드

과제정보

TJP acknowledges the Korean government, Ministry of Science and ICT, for support (No. 2017M2A8A5014859). DS acknowledges the Korean government, Ministry of Science and ICT, for support (NRF-2017R1D1A1B03035418, NRF-2019K1A3A7A09101574, and NRF-2019R1F1A106258). Experiments using synchrotron radiation were supported by Pohang Light Source (PLS-II) at Pohang Accelerator Laboratory (PAL). We thank T. Jeon for the support at beamline 3D at PAL. We thank PK and SS (CNU) for help with XRD measurements. SYL, JHR and JKL (KAERI) are acknowledged for their thoughtful discussions.

참고문헌

  1. R.C. Ewing, Long-term storage of spent nuclear fuel, Nat. Mater. 14 (3) (2015) 252-257. https://doi.org/10.1038/nmat4226
  2. W.-L. Huang, J.M. Longo, D.R. Pevear, An experimentally derived kinetic model for a smectite-to-illite conversion and its use as a geothermometer, Clay Clay Miner. 41 (1993) 162-177. https://doi.org/10.1346/CCMN.1993.0410205
  3. J. Cuadros, J. Linares, Experimental kinetic study of the smectite-to-illite transformation, Geochem. Cosmochim. Acta 60 (1996) 439-453. https://doi.org/10.1016/0016-7037(95)00407-6
  4. R. Mosser-Ruck, M. Cathelineau, A. Baronnet, A. Trouiller, "Hydrothermal reactivity of K-smectite at 300 ℃ and 100 bar: dissolution-crystallisation process and non-expandable dehydrated smectite formation, Clay Miner. 34 (1999) 275-290. https://doi.org/10.1180/000985599546235
  5. K. Ikonen, "Thermal Condition of Open KBS-3H Tunnel," POSIVA 2005-04, Posiva Oy, 2005.
  6. SKB, Design Premises for a KBS-3V Repository Based on Results from the Safety Assessment SR-Can and Some Subsequent Analyses, SKB TR-09-22, SKB, 2009.
  7. JNC, H12 Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan (Supporting Report 2) Repository Design and Engineering Technology, JNC TN1410 2000-003, Japan Nuclear Cycle Development Institute, Tokai, Japan, 1999.
  8. G.R. Simmons, P. Baumgartner, "The Disposal of Canada's Nuclear Fuel Waste: Engineering for a Disposal Facility, AECL-10715, Atomic Energy of Canada Limited, 1994.
  9. P. Wersin, L.H. Johnson, I.G. McKinley, Performance of the bentonite barrier at temperatures beyond 100 ℃: a critical review, Phys. Chem. Earth 32 (2007) 780-788. https://doi.org/10.1016/j.pce.2006.02.051
  10. W.-J. Cho, G.Y. Kim, Reconsideration of thermal criteria for Korean spent fuel repository, Ann. Nucl. Energy 88 (2016) 73-82. https://doi.org/10.1016/j.anucene.2015.09.012
  11. L. Zheng, J. Rutqvist, Jens T. Birkholzer, H.-H. Liu, On the impact of temperatures up to 200 ℃ in clay repositories with bentonite engineer barrier systems: a study with coupled thermal, hydrological, chemical, and mechanical modeling, Eng. Geol. 197 (2015) 278-295. https://doi.org/10.1016/j.enggeo.2015.08.026
  12. P. Sellin, O.S. Leupin, "The use of clay as an engineered barrier in radioactive-waste management - a Review, Clay Clay Miner. 61 (6) (2013) 477-498. https://doi.org/10.1346/CCMN.2013.0610601
  13. R. Pusch, F.T. Madsen, Aspects on the illitization of the kinnekulle bentonites, Clay Clay Miner. 43 (3) (1995) 261-270. https://doi.org/10.1346/CCMN.1995.0430301
  14. R. Pusch, O. Karnland, Geological Evidence of Smectite Longevity: the Sardinia and Gotland Cases, Technical Report TR 88-26, Swedish Nuclear fuel and Waste Management Co. SKB, 1988.
  15. G. Kamei, M.S. Mitsui, K. Futakuchi, S. Hashimoto, Y. Sakuramoto, "Kinetics of long-term illitization of montmorillonite - a natural analogue of thermal alteration of bentonite in the radioactive waste disposal system, J. Phys. Chem. Solid. 66 (2005) 612-614. https://doi.org/10.1016/j.jpcs.2004.06.067
  16. E. Casciello, J.W. Cosgrove, M. Cesarano, E. Romero, I. Queralt, J. Verges, Illite-smectite patterns in sheared pleistocene mudstones of the southern apennines and their implications regarding the process of illitization: a multiscale analysis, J. Struct. Geol. 33 (2011) 1699-1711. https://doi.org/10.1016/j.jsg.2011.08.002
  17. GTS Phase VI, HotBENT. grimsel.com/gts-phase-vi/hotbent-high-temperature-effects-on-bentonite-buffers/hotbent-introduction.
  18. G. Gadikota, F. Zhang, A.J. Allen, Towards understanding the microstructural and structural changes in natural hierarchical materials for energy recovery: in-operando multi-scale X-ray scattering characterization of Na- and Camontmorillonite on heating to 1150 ℃, Fuel 196 (2017) 195-209. https://doi.org/10.1016/j.fuel.2017.01.092
  19. M.-G.-B.-G.-B.-N.-L. Yoo, H.-J. Choi, M.-S. Lee, S.Y. Lee, Chemical and Mineralogical Characterization of Domestic Bentonite for a Buffer of an HLW Reporitory, KAERI/TR-6182/2015, KAERI, South Korea, 2015.
  20. L. Carlson, "Bentonite Mineralogy; Part 1: Methods of Investigation - a Literature Review, Part 2: Mineralogical Research of Selected Bentonites, Posiva Working Report 2004-02, Posiva Oy, Finland, 2004.
  21. H.J. Bray, S.A.T. Redfern, S.M. Clark, The kinetics of dehydration in Camontmorillonite: an in situ X-ray diffraction study, Mineral. Mag. 62 (5) (1998) 647-656. https://doi.org/10.1180/002646198548034
  22. P. Bala, B.K. Samantaray, S.K. Srivastava, H. Haeuseler, Microstructural parameters and layer disorder accompanying dehydration transformation in Na-montmorillonite, Z. fur Kristallogr. - Cryst. Mater. 215 (2000) 235-239. https://doi.org/10.1524/zkri.2000.215.4.235
  23. E. Ferrage, Investigation of the interlayer organization of water and ions in smectite from the combined use of diffraction experiments and molecular simulations. A review of methodology, applications, and perspectives, Clay Clay Miner. 64 (4) (2016) 346-371. https://doi.org/10.1346/CCMN.2016.0640401