Korea has offi cially 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 fi eld demonstration

in the third phase. The outcomes of this study are expected to enhance the scientifi c 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.