Experience with development, designing and use of diagnostic system during nuclear power plant start-up and operation

The application of noise diagnostics for the units of the Bruno Leuschner nuclear power plant (GDR) showed that noise analyses can disclose anomalies in the behaviour of the installation or defects which are otherwise impossible to locate or which would be only found much later if standard instrumentation were used. The noise analysis yields characteristic functions representing the rate of stress upon impacts of metal bodies. Changes in the installation manifest in the static characteristic variables of dynamic signals or in process parameters derived therefrom can originate as early as in the stage of defect formation, so that with sufficient knowledge of the relationships between the process and the defect, defects can be predicted. Experience is reported with checking control assembly vibrations, reactor body and pipe vibrations, with monitoring loose parts, and with the acoustic detection of the loss of coolant. (J.B.)