Improved Flow-Induced Vibration and Work-Rate Measurements of Steam-Generator Tubes
In the past, the excessive fretting-wear of U-bend tubes observed in some nuclear steam generators has led to increased tube inspections, unexpectedly high numbers of plugged tubes and the prospect of degraded performance if left unchecked. In this paper, recent vibration and work-rate experiments that have attempted to address this problem are summarized, including tests of two-span U-tubes in air-water and straight tubes in two-phase Freon. Tube bundles were subjected to two-phase cross-flow over a wide range of flow conditions, measuring tube vibration, flow characteristics in the bundle, and the dynamic interaction (work-rate) between tubes and supports that gives rise to fretting-wear. Developments in vibration and work-rate instrumentation and software analysis tools are also presented. The result is an improved ability to measure dynamic properties and, thus, to better predict the vibration response and fretting-wear performance of steam generators.