Experimental and numerical research on flow-induced vibration characteristics of Hydraulic Suspended Passive Shutdown Subassembly in SFR

Hydraulic Suspended Passive Shutdown Subassembly (HS-PSS) is a passive nuclear safety technology employed in Sodium-Cooled Fast Reactors (SFR). During Sodium Fast Reactors (SFR) operation, this component is often subjected to stress cycles caused by flow-induced vibration (FIV), which may lead to material failure and potentially threaten the reactor's safety. Therefore, it is necessary to investigate and evaluate the FIV behavior of the HS-PSS in fast reactors. Different from the conventional used before, HS-PSS is a new type of control rod assembly with no existing studies on FIV. In this study, we established a full-scale experiment for FIV of the HS-PSS in different flow conditions and with various movable component positions (600 mm, 800 mm, 1200 mm). Modal experiments were conducted to determine the natural frequencies. FIV test results show that the highest amplitude occurs when the movable component is 800 mm, with a noticeable acceleration response near the first natural frequency. To explain the experimental observations, numerical simulations have been conducted to analyze the HS-PSS flow field characteristics. The simulations have considered different positions of the movable component at a fixed flow rate of 16.281 m3/h and different flow rates with the movable component positioned at 800 mm. The results indicate significant changes in the flow distribution within the HS-PSS and the hydraulic forces applied to the inlet surface of the movable component when the movable component is set at 800 mm. The experimental and numerical analysis results of this study have provided valuable insights for analyzing and assessing the FIV behavior of the HS-PSS in Sodium-Cooled Fast Reactors. •A test bench was constructed to study the flow-induced vibration of a Hydraulic Suspended Passive Shutdown Subassembly.•Experiments have discovered the location of special movable parts that respond significantly to vibrations.•The flow field simulation results are consistent with the experimental phenomena, explaining the cause of the vibration response.