Nuclear Engineering and Technology

  • 제53권5호
  • /
  • Pages.1511-1518
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  • 2021
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  • 1738-5733(pISSN)
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  • 2234-358X(eISSN)
한국원자력학회 (Korean Nuclear Society)
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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
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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.

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