Stress Tensor-Based Assessment of Sectional Behavior in Containment Wall Under Increasing Internal Pressure

Ensuring the structural integrity of nuclear containment buildings during severe accidents is critical for preventing the release of radioactive materials. These accidents can lead to internal pressure increases that exceed design conditions, potentially causing cracking in concrete walls and tearing of liner plates. While full-scale crack analysis of the entire containment structure is ideal, it is often computationally prohibitive. This study presents a localized damage assessment method for the APR1400 containment building under elevated internal pressure conditions. A detailed finite element model was developed to simulate pressure loading beyond the design limit. Using the simulation results, a post-processing technique was employed to extract nodal and section forces based on stress tensor data. This allowed the identification of structurally vulnerable wall regions, particularly around large penetrations such as equipment hatches. The proposed method enables the derivation of localized boundary conditions for subsequent crack and leakage analysis, significantly reducing computational cost. It provides an efficient and realistic tool for structural safety evaluations under beyond-design-basis accident scenarios.