Effects of displacement amplitude and normal force on fretting wear behavior of zirconium alloy tube in simulated primary water of PWR

Abstract

Grid-to-rod (GTR) fretting wear was identified as the primary cause of fuel assembly failure. A high temperature pressurized water fretting wear system was designed and fabricated to study the fretting wear behavior between the actual cladding tube and grid dimple. Test parameter combinations of displacement amplitude (±10 ∼ ±50 μm) and normal force (10 ∼ 40 N) were selected by previous fretting map. The findings of the study revealed that the extent of fretting damage on Zr alloy tubes, under the gross slip regime (GSR), was primarily influenced by the displacement amplitude rather than the normal force. It was also noted that the mixed fretting regime could potentially be more hazardous than GSR due to the initiation and propagation of fatigue cracks. In addition, a fretting damage prediction model was successfully developed based on the previous fretting map.