Nuclear Engineering and Technology

Korean Nuclear Society (한국원자력학회)
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Evaluation on the buffer temperature by thermal conductivity of gap-filling material in a high-level radioactive waste repository

  • Seok Yoon (Disposal Safety Evaluation Research Division, Korea Atomic Energy Research Institute (KAERI)) ;
  • Min-Jun Kim (Geology Division, Korea Institute of Geoscience and Mineral Resources (KIGAM)) ;
  • Seeun Chang (Radioactive Waste Disposal Team, Korea Atomic Energy Research Institute (KAERI)) ;
  • Gi-Jun Lee (Disposal Safety Evaluation Research Division, Korea Atomic Energy Research Institute (KAERI))
  • Received : 2022.02.06
  • Accepted : 2022.06.07
  • Published : 2022.11.25
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Abstract

As high-level radioactive waste (HLW) generated from nuclear power plants is harmful to the human body, it must be safely disposed of by an engineered barrier system consisting of disposal canisters and buffer and backfill materials. A gap exists between the canister and buffer material in a HLW repository and between the buffer material and natural rock-this gap may reduce the water-blocking ability and heat transfer efficiency of the engineered barrier materials. Herein, the basic characteristics and thermal properties of granular bentonite, a candidate gap-filling material, were investigated, and their effects on the temperature change of the buffer material were analyzed numerically. Heat transfer by air conduction and convection in the gap were considered simultaneously. Moreover, by applying the Korean reference disposal system, changes in the properties of the buffer material were derived, and the basic design of the engineered barrier system was presented according to the gap filling material (GFM). The findings showed that a GFM with high initial thermal conductivity must be filled in the space between the buffer material and rock. Moreover, the target dry density of the buffer material varied according to the initial wet density, specific gravity, and water content values of the GFM.

Keywords

Acknowledgement

This research was funded by the Basic Research Project (2020R1F1A1072379) and Nuclear Research and Development Program (2021M2E3A2041351) by the National Research Foundation of Korea.

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