Progress in Loose Parts Monitoring

Abstract

Acoustical systems for detection of loose parts in critical components like the primary circuit of a nuclear power plant are installed to increase safety and to prevent costly damages due to loose part impacts. Recently, Framatome improved its system by enhancing the data evaluation methods using suitable mathematical models, and by optimizing the system technology combining loose parts and vibration monitoring functionality.Numerical simulation of an impact and the following wave propagation in realistically shaped structures offer evaluation accuracies which are not achievable using common analytical methods based on idealized infinite plates or infinite cylindrical structures. The numerical simulation allows a substantially better localization than common methods, the determination of the excitation side (inside or outside of the component), the estimation of the mass of the lose part, and a more reliable distinction between acoustic events which are normal for the plant operation and actual loose parts. All this avoids false alarms of the system which is an important quality criterion for such systems in practice.