Physical model study of impact feature of loose parts in NPP

According to the features of elastic wave in metal and the physical properties of loose part impact in primary circuit in NPP, the physical model is established in frequency domain to describe the impact characters of loose parts. The mathematical representation about contacted force existed while loose part impacts the reactor vessel is assumed to be the square of the half-sine function, which is different from the half-sine function found in other publications. The mass of the loose part may be calculated basing on Hertz theory and the model. The loose part impact experiments show that this physical model can be used to describe the impact characters of loose parts in NPP, and the estimated masses of loose parts by the model tally with the measured masses very well. The establishment of the model supplies an effective mean for the anomalous diagnosis of loose parts in NPP