Acceleration signal characteristics of a steel plate, impacted by steel balls, were studied in an attempt to apply the experimental results to the impact location and mass estimation of metallic loose parts in the cooling system of nuclear power plants.
Experimental results show that the variation of maximum acceleration amplitude and impact contact time due to the change of ball mass and impact velocity can be well explained by the Hertz impact theory. The frequency spectral pattern shifted slightly in spite of the increase of impact velocity and impact location. Ball mass, however, strongly affected the frequency spectral pattern. Hence the frequency spectrum can be used for estimation of the mass of unknown loose parts in the cooling system.
Experiments for estimate of the mass and location, using steel loose parts of a sphere, cube, cylinder and plate type, were also performed to verify the derived signal characteristics. The results of mass estimation show that uncertainty range for steel ball is 0.5 to 0.7 decade and for other loose parts 0.8 to 1.0 decade. Impact location was well estimated with an accuracy of 93 percent.
