The acoustic background noise of an operating liquid metal fast breeder reactor, EBR-II

The Upper Plenum Acoustic Experiment (UPAE) at the Experimental Breeder Reactor-II (EBR-II) has obtained acoustic data pertinent to the understanding of the reactor ambient noise background. The primary purpose of these measurements was to characterize the noise background as a function of reactor operating state. These data provide a basis for the system design and normality criteria for an acoustic surveillance system. The experiment was composed of an acoustic probe with three high temperature lithium niobate microphones and one waveguide in the upper plenum, one microphone and waveguide in the outer pool of sodium and accelerometers on the primary pumps and key structural members. Data has been obtained and analyzed as a function of reactor flow. An empirical correlation with total volumetric flow is presented. The background noise spectra, and probability density are presented and the significant features of these data are discussed in terms of flow induced vibrations, pump noise and reactor internal transmission properties.