Method and installation for welding a spacer grid of a nuclear reactor fuel assembly and apparatus for welding from the grid interior

摘要

Metal strips arranged on edge and in criss-cross fashion to form a grid defining an array of cells are welded together using an assembly of at least four laser welding heads which are moved simultaneously into and at least part way along the axial length of at least four cells to weld the strips together along the cell corners. Also claimed is a welding assembly comprising a tubular body able to move along a cell and enclosing optics to direct a radiation beam from a window at the lower end.