Development of Nondesttructive Testing Techniques for the Evaluation of Hydrogen Concentration in Zircaloy Claddings---Effetcs of Hydride Orientation(III)

Zircaloy cladding materials suffer a loss of ductility during reactor service due to neutron irradiation and hydrogen uptake from the cladding waterside corrosion reaction. The radiation damage is generally believed to be dominant in the reduction of Zircaloy cladding ductility, however, the hydrogen embrittlement also plays an important role. Hot Lab. techniques such as inert-gas fusion, hot vacuum extraction, mechanical material testing techniques and SEM microscopy are usually used for the characterization of hydrogen embrittlement effects. However, these techniques are expensive and require destructive inspections. Poolside nondestructive evaluation (NDE) techniques are desired for these inspections. For the past two years, we have demonstrated two ultrasound NDE techniques for successful quantitative evaluation of hydrogen concentration (HC) in Zircaloy claddings. These two NDE techniques include an acoustic microscope (AM) technique and a laser ultrasound technique (LUT). However, it is found that the degradation of mechanical properties due to hydrogen is also influenced by the orientation of the hydride. Usually, the hydride is formed in a Zircaloy tube in both radial and circumferential directions. The mechanical properties are influenced by the HC and the ratio of radially orientated hydride and circumferentially orientated hydride. In this project, the combined effects of HC and hydride orientation on the propagation behaviors of guided waves propagating in Zircaloy tubes are proposed to be investigated.

Project ID:PB9402-0094
External Project ID:NSC94-2623-7182-002