An automatic diagnosis method for loose parts monitoring system

Generally, it is known that loose parts in the reactor coolant systems (RCS) bring serious damage into the system components and impede the normal function of the system. So, it is necessary to rapidly respond when the impact event has occurred. This paper presents a realization of automatic diagnosis algorithm for LPMS (loose parts monitoring system) and application results to the impact test data at YGN 3. The developed algorithm is composed of three parts; prefiltering, impact location and mass estimation. The prefiltering is needed to reject low frequency background noises. To estimate the impact location, the starting points of impact are detected from the filtered signals and compared to produce the time differences, and then the triangulation is applied. To estimate the mass and energy of a loose part, we first compute the maximum amplitude and the initial half period. And a modified impact theory considering amplitude and energy attenuation effects is applied.