Thermo-mechanical Analysis of a High-level Radioactive Waste Repository Considering the Excavation-damaged Zone (EDZ) Length

This study evaluated the influence of the length of the excavation-damaged zone (EDZ) on the thermomechanical response and stability around deposition tunnels in a KRS+-based deep geological repository using three-dimensional finite element analysis.Time-dependent thermal analysis was performed by applying decay heat after the cooling period as a volumetric heat source, and the resulting temperature field was coupled to a quasi-static mechanical analysis in a one-way manner.The EDZ is represented as a damaged zone with reduced thermal transport properties and degraded mechanical parameters relative to intact rock.Failure proximity was quantified using the Mohr-Coulomb stress ratio.The EDZ length affected both the temperature distribution and stress redistribution patterns with pronounced, location-dependent sensitivity, particularly near the bufferbackfill interface and corner regions.These findings suggest that the extent of the EDZ should be treated as a design variable and explicitly considered in long-term safety assessments.