B211 THE EXPERIMENT OF FLOW INDUCED VIBRATION IN PWR RCCAs(Nuclear power-3)

概要

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The Rod Cluster Control Assemblies(RCCAs) of Pressurized Water Reactor(PWR) plant are used for the power control and reactor shutdown by inserting them into or withdrawing them from the core. On normal operation, the shutdown rods are all out from the core and locate in the upper guide tube. Recently, very severe wear on the shutdown rod cladding of Ulchin Nuclear Power Plant #1, #2 was observed by the eddy current test(E.C.T). In particular, the wear at the sixth card location was up to 75%. The test results indicated that the fretting wear is caused by the flow induced vibration(F.I.V.) contact between RCCAs and their spacing cards(guide plates) arranged in guide tube. To identify the governing mechanism of RCCA vibrations, an experimental work was performed in experimental rig designed and manufactured to satisfy the governing non-dimensional numbers which were Reynolds number and damping parameter. The vibration amplitude measurement by the non-contact laser displacement sensor showed a good agreement of the maximum wearing(vibration) distribution with Ulchin E.C.T. results and Framatome report, respectively. Comparing the rod behavior with the idealized response of a cylinder in vibration, it was found that the dominant mechanism of vibration was periodic shedding at the mass flow, 100 l/min.
一般社団法人日本機械学会の論文
2000-10-01