Advancements in Long-term Safety Evaluation Technology for Engineered Barrier System (EBS): A Comprehensive Review of Korea’s High-Level Waste Disposal R&D Program

Korea has officially initiated the development of an underground research laboratory (URL) at a depth of 500 m to facilitate a full-scale demonstration of high-level radioactive waste disposal technology. With the establishment of the URL, validating the long-term performance of the engineered barrier system (EBS) under deep geological conditions has become a critical priority. This paper presents Korea’s research plans and technological advancements in the long-term safety evaluations of EBS, a key component of a recently launched multi-ministerial R&D project for spent nuclear fuel management. The primary objective of this project is to assess the long-term integrity of EBS by analyzing coupled interactions with the disposal system as the real disposal environment evolves. The research is divided into four key areas: (1) establishing performance criteria for engineered barrier materials, (2) characterizing interactions among EBS components, (3) investigating coupled Thermo-Hydro-Mechanical-Chemical (THMC) behaviors, and (4) developing core technologies for in situ validation of EBS performance and coupled interactions. This nine-year project (2021–2029) is currently in its second phase(2024–2026), focusing on engineering-scale experiments, numerical model development, and preparation for large-scale field demonstration in the third phase. The outcomes of this study are expected to enhance the scientific basis for safety assessments and licensing in a disposal repository, as well as serve as a bridge for full-scale research at actual disposal depths utilizing URLs.