Acoustic Noises with Loss-of-Flow Sodium Boiling Experiment in a 19-Pin Bundle

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Y.Ozaki*; Haga, K.*; Kikuchi, Y.*; T.Morik*; M.hori*

Y.Ozaki*; Haga, K.*; Kikuchi, Y.*; T.Morik*; M.hori*

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This paper deals with the measurement of acoustic noises with sodium boiling in an electrically heated 19-pin bundle which simulated an LMFBR fuel subassembly. The intensity of boiling acoustic noises measured with the waveguide method was much higher than the background noises such as mechanical and flow noises. A distinct peak, which was observed at approximately 10 kHz, may be attributed to the peculiarity of sodium boiling phenomena because this peak could easily be distinguished from the resonance peaks of the experimental system. The waveform of the boiling acoustic noises was similar to the burst type acoustic emission (AE). The propagation speed of acoustic noises agreed well with a prediction by the theory based on the assumption that the measured acoustic signals were transmitted on the pipe as surface waves (Rayleich waves) or Lamb waves.