Evaluation of ultrasonic attenuation and estimation of ultrasonic grain noise in copper

This paper presents a method for evaluating ultrasonic attenuation and estimating ultrasonic grain noise in solids. The method is aimed at evaluation of various grades of copper used during manufacturing canisters for spent nuclear fuel. The spectral shift method has been employed for the evaluation of attenuation, and the independent scattering model (ISM), proposed by Margetan er at ((1)), has been used for the estimation of ultrasonic backscattering in immersion test. The attenuation coefficients evaluated for a number of copper specimens covering a certain range of grain sizes and having large attenuation have shown a clear correlation between the grain size in specimens and the attenuation. The comparison of the root-mean-square (RMS) of grain noise signals from the specimens determined from the measurements with those predicted by the ISM has shown that the ISM is a good estimator of the grain noise signals, especially in the shallow regions of the specimens.