Effect of applied current on the formation of defect in PWR nuclear fuel rods in resistance pressure welding process

Abstract

The welding of zirconium alloy components is one of the most critical processes in the fabrication of nuclear fuel rods used in pressurized water reactors. For this, various welding processes, such as gas tungsten arc welding, electron beam welding, laser beam welding, and resistance pressure welding (RPW), are used around the world. In Korea, the RPW process is being used to fabricate nuclear fuel assembly fuel rods. This study investigated changes in the weldment shape owing to welding conditions such as welding current, welding force, and overlapping. The welding soundness of the weldment was evaluated by hydraulic burst test. The welding temperature of the weld zone was measured using a thermal infrared method. Discontinuous black spots in the weld line, regarded as a non-bonding defect, were confirmed as spots caused by the carbide precipitation of zirconium during welding.

Analysis of Foreign Substance Flow within the Weld Joint through Simulation in Pressurized Water Reactor Nuclear Fuel Rods

“…In general, the integrity of the resistance welds is verified through the burst test and macrograph test, which are the destruction tests, before and after the fuel rods are produced. When testing for integrity, there have been cases where carbide-based ceramic material with a higher melting temperature than the base metal has been found in the weld joint, and such material may affect the quality of the weld [8]. The purpose of this study is to find the optimal welding conditions for moving these foreign substances to the outer part of the tube.…”