Control rod absorber section fabrication by square tube configuration and dual laser welding process

This patent describes a process for the assembly of a planar section of a cruciform shaped control rod from tubes. It comprises: providing tubes, the tubes having cylindrical interior volumes for the containment of neutron absorbing poisons and having square external sections for being joined by welding in side-by-side relation; filling the cylindrical interior volumes with neutron absorbing poisons; plugging the tubes to seal the neutron absorbing poisons within the tubes: providing a jig for maintaining the tubes in side-by-side relation to form a planar section of the control rod, the jig having a leading end for holding the ends of the tubes in side-by-side relation and having a trailing end for holding the tubes in side-by-side relation