On the reproducibility of the parallel-flow induced vibration of fuel pins

Abstract The influence of the test loop on parallel-flow-induced vibration of fuel pins of the Na 1 fast reactor design was investigated. The experiments were performed with the same subassembly mock-up, mounted in the test section of four different flow loops with several modification. In spite of a broad variation of the level (1:10) and the structure of pressure fluctuations at the water inlet into the subassembly, only moderate scatter (± 50%) of the level and a slight variation of the structure of the vibrating response of the pins were observed. Experimental results are presented in the form of diagrams of normalized rms-values of pressure fluctuations and vibration strains plotted over the Reynolds number. The structure of pressure fluctuations and vibration strains is illustrated by several typical spectral density plots.