Papers by Keyword: Nondestructive Characterization

Abstract: In order to reduce noise disturbance of alternating current field measurement (ACFM) signals in crack defects detection, a new noise cancellation method called empirical mode decomposition (EMD) was proposed. A butt welded plate specimen was inspected and measured by a hand-held ACFM probe and a TSC AMIGO instrument. The original ACFM signal was first decomposed into different intrinsic mode functions (IMFs) and a residue, and some IMFs containing useful information were subsequently reconstructed based on correlation coefficients. The experimental results show that the reconstructed ACFM signals B_x and B_z, and butterfly plot can characterize crack defects more accurately, demonstrating the feasibility and effectiveness of the proposed method.

Abstract: Zirconium alloys are used for many applications in nuclear components, such as the pressure tube material in a pressurized heavy water reactor, nuclear fuel cladding, etc. One of the problems during the operation of a nuclear reactor is the degradation of the zirconium alloys, which is due to an increase of the hydrogen content in the zirconium alloy. Therefore a non-destructive determination of the hydrogen concentration in zirconium alloy is one of the important issues that need to be addressed. The resonant ultrasound spectroscopy (RUS) technique is evaluated for a characterization of the hydrogen concentration in Zr-2.5Nb alloy. Referring to the terminal solid solubility for dissolution (TSSD) of Zr-2.5Nb alloy, the plot of the mechanical damping coefficient (Q-1) versus the temperature or the deviation of the resonant frequency for the temperature (df/dT) versus the temperature was correlated for the hydrogen concentration in Zr-2.5Nb alloy. It was found that the temperature at an abrupt change of the slope can be correlated with the hydrogen concentration of the Zr-2.5Nb alloy.