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.

1. Introduction
2. Performance Test Facility for DisposalCover
    2.1 Disposal Cover of the Performance TestFacility
    2.2 Monitoring Room
    2.3 Specifications of Soil Materials Used inActual Construction
3. Numerical Simulation of Disposal Coverin Performance Test Facility
    3.1 Governing Equations
    3.2 Conceptual Model of NumericalSimulation
    3.3 Boundary Conditions and InputParameters
    3.4 Mesh of Numerical Model
4. Results of Numerical Simulation
    4.1 Distribution of Saturation
    4.2 Flux of Water Infiltration
5. Conclusion
Conflict of Interest
Acknowledgements
REFERENCES

• Mijin Kwon(Korea Radioactive Waste Agency, 174, Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea)
• Seho Choi(Korea Radioactive Waste Agency, 174, Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea)
• Chunhyung Cho(Korea Radioactive Waste Agency, 174, Gajeong-ro, Yuseong-gu, Daejeon 34129, Republic of Korea) Corresponding author