英文摘要 |
In order to highlight the vulnerability of Residual Heat Removal(RHR) piping systems for fragility analysis, a segment of the RHR piping that includes a heavy motor operated valve(MOV), a flanged joint, and reducer was numerically modelled to simulate the dynamic behavior during strong earthquakes. Three kinds of tests were completed in this study to verify the accuracy of the numerical model. First, pure bending tests with four-point cyclic loading were adopted for the flanged joint to investigate the nonlinear behaviors and establish reliable component models using finite element analysis software. Second, quasi-static tests for the chosen segments of piping were executed to carefully observe the response of the piping under cyclic loading. Finally, shaking table tests were completed to investigate its dynamic characteristics and to verify the results of the numerical analysis. According to the test results, the seismic performance of the RHR piping system in the sample NPP is better than the assessment results in the FSAR. However, it’s noted that an unexpected failure mode of the flanged joint occurred during the pure bending test and caused the leakage of the tested specimen. |