METHOD FOR MANUFACTURING FUEL ELEMENTS AND ARRANGING THEM IN FUEL ASSEMBLIES Russian patent published in 1999 - IPC

FIELD: nuclear power engineering; water-moderated power reactors. SUBSTANCE: prior to launching tubes in production, they are subjected to ultrasonic inspection by rotating piezoelectric transducers about them. Outer and inner parts of tube wall at its one end are blunted and two cones are made at its second end upon its trimming to fit can size. Butt end of double-cone can is calibrated for seating surface of plug. Can is degreased by solvents which do not impair quality of fuel elements. First plug is press-fitted into first calibrated end of can with interference fit. Removable taper bush having ground inner surface is placed between collet chuck and welding chamber of resistance butt- welding machine. Gas is evacuated from welding chamber beyond seating surface of collet chuck. Removable insert having resistance of 300-1500 mcOhm is inserted in collet chuck to supply current through it and to transfer heat in the course of welding. Film coating is formed on each fuel element, lubricating oil is applied to it during press-fitting, and end pieces are put on. Fuel elements are assembled in cells of spacer grids. Lubricant and varnish film are removed from assemblies. The latter are dried out and subjected to air-tightness tests. EFFECT: improved quality of fuel elements and assemblies; improved yield. 13 cl, 11 dwg