Development of a LASER Welding Apparatus and a Method for an Inner-Strap Welding of a Spacer Grid Assembly for a PWR Fuel Assembly

Abstract

A spacer grid assembly, which is an interconnected array of slotted grid straps welded at the intersections to form an egg crate structure, is one of the core structural components for the nuclear fuel assemblies of a Pressurized light Water Reactor (PWR). The commercial spacer grid assembly is spot-welded at the crossing points of the intersections by a TIG welding, LASER beam welding or Electron beam welding method. In this study, a LASER beam welding apparatus and a method for an inner strap welding has been proposed to obtain a longer and finer weld line and a smaller weld bead size for a spacer grid assembly for a PWR fuel assembly. Also a rapid welding and excellent weld quality have been achieved by the proposed welding apparatus and method.