METHOD OF MANUFACTURING FUEL ASSEMBLY SUPPORT GRID

摘要

PURPOSE: To improve the corrosion resistance of a weld part so as to sufficiently withstand high efficiency operation. CONSTITUTION: A support grid is formed by assembling a plurality of straps in grid shape. The intersecting parts of the respective straps are welded and then subjected to recrystallization annealing. The recrystallization annealing is performed in a heat treating furnace in a vacuum or inert gas atmosphere, and as the recrystallization annealing condition, the heating temperature is set to 430-750°C and held for 0.5-24 hours. In the strap of a zircaloy, the crystal of a β-phase which is a high temperature metal phase is changed into a prior β-phase of quenched texture by quenching after welding, to lower corrosion resistance, but the prior β-phase of the quenched texture of the weld part is adjusted by recrystallization annealing afterwards to precipitate intermetallic compounds Fe, Cr in the supersaturated state, thus improving the corrosion resistance of the weld part.