Disposal cover as an engineered barrier of a near-surface disposal facility for low and very low-level radioactive waste is composed of a multi-layer to isolate radioactive waste from environmental influences for the long term. To acquire a realistic forecast for the post-closure period of the disposal facility, it is essential to carry out long-term experimental research in a similar condition to the actual disposal environment. Hence, a performance test facility of the disposal cover was constructed in Gyeongju low and intermediate level radioactive waste disposal center in 2022. The constructed performance test facility has differences from the material properties presented in the design. These differences are factors that affect the prevent rainfall infiltration, which is one of the important roles of the disposal cover. Therefore, in this study, a numerical simulation of rainfall infiltration into the performance test facility was performed for the designed case and the actual constructed case. To simulate the behavior of water infiltration, the FEFLOW software based on the finite element method is used. Through the analysis of numerical simulation results, it is confirmed that the hydraulic conductivity of the material constituting the multi-layer of the disposal cover greatly influences the amount of water infiltration.

Radioactive waste disposal facility in Korea, radioactive waste packaged in 200 L drums is placed in a concrete disposal container and disposed of at an underground silo type (cave) disposal facility. At this time, the disposal container cover is seated on the top of the disposal container, and if the disposal container and the cover are not completely combined, the container cover is raised up from the top of the disposal container, so safety problems may occur when stacking the disposal container. Therefore, various methods exist to secure a margin for the pure height inside the disposal container. The disposal container cover only covers the upper surface of the container to shield radiation, and structural performance is not required. Therefore, the method of processing the cover, such as a method of making the cover of the disposal container thin, is the easiest method to apply. In this study, a method to reduce the thickness of the cover of a concrete disposal container was devised, and structural performance under usability conditions such as lifting and seating was analyzed. In addition, the disposal container cover has a reinforced concrete form in which dissimilar materials (concrete and steel) are combined, an integrated analysis was performed to secure the reliability of the analysis results for this, and the analysis results were described. It was found that the proposed disposal container cover structure can improve usability by reducing the stress concentration phenomenon.

중저준위 방사성폐기물 천층처분시설의 처분덮개설계 및 성능평가를 위해 국내 역사시대 고분연구를 수행하였다. 처분덮개 성능과 관련된 국내외 연구현황을 조사하고 삼국시대 고분을 중심으로 봉분의 층상특성을 정리하였다. 국내 고분에 대한 봉토의 시료채취와 시료에 대한 수리전도도 측정 및 분석을 실시하였다. 고분에 대한 자연유사 연구에서 발굴조사보고서 상에 제시된 봉토의 유사판축기법의 적용, 모세관 방벽현상과 배수로를 이용한 봉분 내 습도조절 여부를 천층처분 시설설계에 활용할 수 있을 것으로 판단된다. 향후 국내 고분발굴현장이 있을 때 현장을 방문하여 필요한 자료수집과 더불어 원자력분야의 관심사와 필요사항에 대하여 국내 고고학계와의 정보교환이 이루어져야 할 것으로 판단된다.