Localization of In-Core Disturbances with Ex-Core Detectors

A method, for locating disturbances taking place inside an operating reactor by analyzing radiation emitted from the core, uses two gamma-ray collimator-detectors to selectively monitor information from specific regions of the core. An analog computer was programmed to perform a cross-power spectral density analysis of the information and to eliminate information not common to both channels. A periodic disturbance worth ∼ 50 millicents was used for the investigation. Disturbances located ∼ 4 in. inside the core were detectable with the present system. With moderate improvement in equipment, it is expected that perturbations located 1 ft inside cores of similar composition could be located.