관통부를 포함한 원자로 압력용기의 상세 중대사고 해석을 위한 Alloy 600/82의 재료 모델 개발 = Development of Alloy 600/82 Material Models for Detailed Severe Accident Analysis of Reactor Pressure Vessel Including Penetration

다국어 초록 (Multilingual Abstract)

In this work, material deformation and fracture models for Alloy 600 (nozzle material) and Alloy 82 (weld material) of reactor pressure vessel (RPV) penetrations are presented to accurately evaluate structural integrity under severe accident conditions. For Alloy 600, an integrated model was established to cover a wide range of temperatures (20–1,100 °C) and strain rates (0.001–1%/s). A plasticity model was formulated to improve the prediction accuracy of deformation behavior beyond the ultimate tensile strength (UTS)—a limitation of existing constitutive equations—and was coupled with a creep model based on creep rupture test data. In addition, a temperature-dependent failure model incorporating physical phenomena such as ductility minimum and recrystallization was developed. For Alloy 82 weld material, the plasticity model was adopted by benchmarking the mechanical properties against the nozzle material, while creep and failure behaviors were modeled based on separate experimental data. The reliable material models developed in this study are expected to provide an essential foundation for enhancing the accuracy of detailed RPV penetration analyses and severe accident scenario assessment.