Fundamental Study of Zircaloy-4 Tube Welding Using a Fiber Laser

The irradiation test of Zircaloy-4 tube specimens using a LVDT(Linear Variable Differential Transformer) for the pressure and elongation was planned for the evaluation of a nuclear fuels performance. To establish the fabrication process, and for satisfying the requirements of the irradiation test, an LBW(Laser Beam welding) machine using a fiber laser source was developed, and the preliminary welding experiments for optimizing the process conditions of the specimens of Zircaloy-4 cladding tube to LVDT housing part were performed. Small tubes with a 12.12mm diameter and a 0.6mm wall thickness have been used and the optimum conditions of the circumferential welding have also been selected. This paper describes the experimental results of the LB welds of the specimens of Zircaloy-4 small tube and the metallographic examinations of the LB welded specimens for various welding conditions for the fuel irradiation test. These investigations satisfied the requirements of the fuel irradiation test using a radiation-resistant LVDT for the pressure and elongation and the LB welds for the specimens of the small tube at the HANARO research reactor