WELDING TECHNIQUE FOR SPACER GRIDS OF NUCLEAR- REACTOR FUEL ASSEMBLIES

摘要

nuclear reactors. SUBSTANCE: highly productive universal welding process aimed at improving performance characteristics of spacer grids in the course of long-time service includes additional compression of cellular field of grid and keeping it so throughout entire welding time; in the course of displacement of electrodes the latter are checked for their unwanted contact with cells being welded; if this is the case, electrode position is corrected and mentioned check repeated until contact is eliminated; distance between side surface of electrode and boss holding fuel element in position is always shorter than that between edge of electrode effective surface and face adjacent to that being welded. Welding is effected in row-by-row manner while skipping over cells located in vicinity of guide channels; surfaces to be welded are pre-deformed due to heating pulse without forming metal bond between them; when effective surfaces of electrodes need cleaning, this procedure is made automatically without removing them from welding gun. EFFECT: improved welding rate and quality of grid. 7 dwg