Buffer materials play an important role in preventing the leakage of radionuclides from the residue. The mineralogical properties of these buffer materials are critical in repository design. This study presents the fundamental properties of Na-type MX80 and a novel Ca-type Bentonil- WRK. The CaO to MgO ratio in Bentonil-WRK was approximately 1:1, and the CaO to Na2O ratio was approximately 2.8:1. These results suggest that Bentonil-WRK demonstrates a lower swelling index compared to Gyeongju bentonite due to its CaO-to-MgO ratio’s proximity to 1:1, despite having a higher montmorillonite content than Gyeongju bentonite. The results of this research can provide useful foundational data for the evaluation of the thermal-hydraulic-mechanical-chemical behavior of buffer materials.

• Mihye Kong(Korea Atomic Energy Research Institute (KAERI)) Corresponding author
• Gha-Young Kim(Korea Atomic Energy Research Institute (KAERI))
• Minsoo Lee(Korea Atomic Energy Research Institute (KAERI))
• Junhyuk Jang(Korea Atomic Energy Research Institute (KAERI))
• Jin-Seop Kim(Korea Atomic Energy Research Institute (KAERI))