Assessment of the Performance of a Conceptual Acoustic Surveillance System for Anomalous Events in LMFBRS

摘要

A method is developed for calculating the detectability of anomalous acoustic events. The example used is the sodium vapor bubble collapse in the subcooled regions of a Liquid Metal Fast Breeder Reactor (LMFBR). This method provides a range of estimates for detection and false alarm probabilities in acoustic surveillance systems for sodium boiling and voiding detection, as well as any other impulsive events such as loose-parts monitoring. The signal excess at the receiver array from an impulsive source is computed by an extension of methods introduced by W. Carey. Assuming an exponential pulse form for the signal (or its envelope) the equivalent source level is determined from the energy flux spectral density for inclusion in the sonar equation. The signal excess (SE) is then given by the source level (SL) minus the noise level (NL) minus the transmission loss (TL) minus the detection threshold (DT) plus the receiving array gain. (ERA citation 03:014715)