Evaluation of Flow-Induced Vibration for Fixed Type Guide Rods of Shroud Head and Steam Dryer in ABWR

For the purpose of shortening outage schedules, fixed type guide rods are expected to be used in the ABWR. Guide rods are the component for a shroud head and a steam dryer installation. However, guide rods are located near the main steam nozzle, therefore flow-induced vibration (FIV) is concern due to the high steam velocity. In the present study, tests of the 1/1.87-scale model and computational fluid dynamics (CFD) analysis for the 1/1.87-scale test and the actual ABWR model were conducted to prove the structural integrity of fixed type guide rods against FIV. As a result of CFD calculation, reduced damping was more than 5 and reduced velocity was approximately 1.44, so resonance did not occur fixed type guide rods. The maximum fluctuating stresses were conservatively evaluated as 8MPa by the turbulence and 2MPa by the Karman vortex shedding. Both values were below allowable limit. As noted above, the structural integrity against FIV was confirmed, so it is feasible to use the fixed type guide rods in the ABWR.