Acoustic frequency analysis of the vibrational resonant frequencies of Special Nuclear Material containment

The increase of the resonant frequencies of a Magnox containment package that have been detected by an electromagnetic acoustic transducer and a microphone, are the result of an increase in internal pressure of the package. Therefore, it is possible to infer an internal pressure measurement of the Magnox package by measuring the shift of different resonant frequencies. A model of the Magnox package has been constructed to predict the acoustic vibrational resonant frequencies of the package wall and the corresponding mode shapes. Laser Doppler vibrometer measurements of the Magnox package wall have confirmed the presence of the predicted mode shapes and the resonant frequencies at which they occur have been reasonably estimated by the model.