The diagnostics of a nuclear reactor by the analysis of boiling sound

This paper is described on the basic research concerning the method of detecting abnormality by analyzing boiling sound when the heat transfer to coolant became locally abnormal in a pressurized nuclear reactor. In this study, the power spectra of sound were grasped as a sort of pattern, and it was aimed at to diagnose exactly the state in a reactor by analyzing the change with an electronic computer. As the calculating method, the theory of linear distinction function was applied. The subcritical experimental apparatus was used as a simulated reactor core vessel, and boiling sound was received with a hydrophone, amplified, digitalized and processed with a computer. The power spectra of boiling sound were displayed on an oscilloscope, and the digital values were stored in a micro-computer. The method of calculating treatment of the power spectra stored as the data in the microcomputer is explained. The magnitude of the power spectra was large in low frequency region, and decreased as the frequency became higher. The experimental conditions and the results are described. According to the results, considerably good distinction capability was obtained. By utilizing the power spectra in relatively low frequency region, the detection of boiling sound can be made with considerably high accuracy. (Kako, I.)