A Simplified Dynamic Model for the Vibration Frequencies and Critical Coolant Flow Velocities for Reactor Parallel Plate Fuel Assemblies

The response of flat, thin, parallel, metal fuel elements to the loads imposed by the flow of coolant through reactor core passages is examined for the existence of plate divergence at velocities above a critical'' value. lt is shown that small modifications of the simplifying assumptions used in the analysis produce a great difference in the conclusions regarding the possibility of divergence and the interpretation of the critical'' coolant velocity. Fluid inertia effects are included in the analysis of the periodically supported plates. Although agreement exists between the results of the dynamic model and that of neutral equiliotium,'' the additional consideration of fluid inertia leads to a different interpretation of critical' velocity for the periodically supported plates. (auth)