Background:Core shroud is an important assembly

which forms the lateral periphery of the core inside the core barrel.Purpose:To carry out a dynamic property test on a core shroud mockup(1:1) at the damping

natural frequency and the corresponding vibration mode of AP1000 reactor internal core shroud assembly in air.Methods: The multi-input multi-output(MIMO) test method was used in this modal test.Results:By such test

the first six mode natural frequencies

damping and vibration modes of the core shroud assembly were obtained.Conclusions: The test results would be used to offer natural parameters of the core shroud assembly for AP 1000 reactor equipment system model and flow-induce vibration analysis of the core shroud assembly.