Active health monitoring of TN32 dry cask using a scaled down model

TN32 casks are multi-layer cylindrical structures used for storage of nuclear spent fuel. The National Center for Physical Acoustics at the University of Mississippi has manufactured a scaled down model of the TN32 cask. To identify the most relevant nondestructive evaluation parameters, which will be useful while doing experiments on real TN32 casks, a series of experiments have been conducted on TN32 cask model. This paper discusses the data analysis of the experiments conducted on the cask model and the conclusions based on those experiments. Elastodynamic waves are generated in the cask model by pencil lead break and hammer hit excitation and the waves in the cask at certain locations are sensed using piezoelectric wafer active sensors (PWAS). The waveforms and frequency spectrums of waveforms arriving at PWAS are studied. There are two types of joints on the cask model: structures joined using adhesives and structures joined using press fit. The effects of various joints in the structure on elastodynamic wave propagation are also studied. Pitch catch experiments on the cask was also done using in plane excitation using PWAS. The most sensitive frequency for the cask model was identified from the frequency response spectrum obtained from a wide band chirp excitation. The influence of various joints on the frequency response spectrum is also studied. Analytical modeling of cask geometry for a given excitation is done using Normal Mode Expansion (NME) technique. Prediction of wave propagation through the scaled down model is done based on the theoretical expression derived.