Method and apparatus for welding criss-crossed strips of a fuel assembly spacer grid from the exterior of said grid

摘要

Metal strips arranged on edge and in criss-cross fashion to form a grid (20) defining an array of open-ended cells are welded together by laser beams directed into the cells from the two sides of the grid, at least four cell corners being welded simultaneously in each of a series of welding steps. Between steps the grid is moved in its own plane relative to the welding heads. Also claimed is a welding plant comprising a sealed chamber (22) for enclosing the grid in an inert atmosphere and having two opposed windows (23) through which the laser beams are directed from external welding assemblies which are movable perpendicular to the grid plane to weld the cell corners.