Laser Welding of Ta Sheath for a Thermocouple Wire for an Instrumented Fuel Irradiation Test

This work was carried out to obtain sound welds and to select the most suitable binary metal joint among three different dissimilar binary metal combinations such as Zr-4/Ta, Mo/Ta and Ti/Ta(seal tube/sensor sheath) joints for an instrumented nuclear fuel irradiation test. To do this, the Taguchi experimental method was employed to optimize the experimental data. In addition, metallography, a micro-focus x-ray radiography and a hardness test were conducted to examine the welds. From the weld bead appearance, penetration depth and bead width as well as weld defects standpoint, the Zr-4/Ta joint is suggested for a circumferential joining between a seal tube and a sensor sheath. The optimized welding parameters based on the Zr-4/Ta joint are suggested as well.