[3F11-16] Improving Resilience of Nuclear Structure

[3F13] Development of failure mitigation technologies for improving resilience of nuclear structures

(17) Study on mitigation of post-buckling damage of fast reactor vessel during excessive earthquakes

*YIJI YE¹, Sho Hasegawa¹, Masakazu Ichimiya¹, Naoto Kasahara¹ (1. UTokyo)

Keywords:Beyond design basis earthquakes, Fast reactor vessel, Buckling and post buckling, SDOF, FEM

The main vessels of fast reactors are thin-walled large-diameter cylindrical structures, of which buckling is considered as one of the critical failure modes under excessive seismic load. Post-buckling stability is also an essential issue to maintain coolant level against beyond design basis earthquakes. This study aims to clarify the buckling and post-buckling characteristics of thin-walled cylinders under severe vibration by combined analyses of Single Degree Of Freedom (SDOF) model and FEM. A nonlinear SDOF model is able to capture the global response of the structure and verified by FEM results, while FEM enables efficient evaluation of local behavior. In addition, the occurrence conditions of fatigue damage after buckling represented by input energy and input frequency ratio are analyzed based on the analytical data. A stabilization diagram against post-buckling damage is obtained, which can be applied to fast reactor vessel under beyond design basis earthquakes.