Material characterization for Zircaloy claddings in elevated temperatures using a laser ultrasound technique

Material properties of Zircaloy cladding can degrade substantially and threaten the fuel integrity while in nuclear reactor service at elevated temperature. Other than radiation exposure, precipitated hydrides are also shown to be responsible for hydrogen embrittlement of the claddings. A procedure corporate with an experimental technique is used to investigate the effects of high temperature on the dispersion spectra of guided waves. A laser ultrasound technique (LUT) is used to measure the dispersions of guided waves propagating along the axial direction of the cladding tubes at different temperature environment. It is shown that the LUT is able to measure the dispersion curve of Zircaloy in the elevated temperature environment. The dispersion spectra shift towards the direction of lower frequency and lower velocity while the temperature increase. With the inversion procedure, material properties such as elastic modulus is successfully characterized in various elevated temperature. The Young´s modulus is found to decrease linearly as the temperature increasing. This research is focuses on the characterization of material properties, elastic moduli in particular, at elevated temperatures for Zircaloy cladding tubes of various hydrogen concentrations (H.C.).