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H.Araki*; T.Komab*; Sato, Kazujiro*; Y.Ozaki*; H.Inuzi*; K.Koday*; Y.Shino*
PNC TN941 81-114, 11 Pages, 1981/06
Some studies for confirmation of the usefulness of the measurements of boiling sound and fluctuations of sodium temperature, flowrate and neutron flux for detection of sodium boiling have been curried out in Japan. For the development of acoustic detection system, acoustic transmission decay and velocity change by fuel pins, gas plenum and neutron shield were measured. Acoustic transmission from the reactor core to the detectors which were installed in the upper core structure and the upper flange of reactor vessel were studied theoretically and experimentally using the reactor vessel mockup. Sodium boiling acoustic spectra which were dependent of detector positions were obtained in the out-of-pile experimental facility. Acoustic background caused by flow and electric noise were measured in the Experimental Fast Reactor. On the other hand, coolant temperature and flowrate fluctuations caused by the sodium boiling were measured by the Temp/Flow detector which were mounted on the outlet of fuel subassembly. Simulation tests by computer on the correlation method between neutronic and acoustic signals were carried out. Current status and future plans about these studies in Japan are summarized briefly in this paper.
Y.Ozaki*; Haga, K.*; Kikuchi, Y.*; T.Morik*; M.hori*
PNC TN941 78-140, 9 Pages, 1978/10
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.
