METHOD FOR MANUFACTURING FUEL-ASSEMBLY SPACER GRIDS Russian patent published in 2004 - IPC

FIELD: nuclear power engineering. SUBSTANCE: method for manufacturing spacer grids from stainless steel tubes includes thermal treatment or stabilizing annealing. The latter is given to original thin-walled tubes prior to vacuum cutting them into metered billets for subchannels of spacer grids at residual pressure and for time sufficient to raise corrosion resistance of stainless steel. Separate subchannels are formed from billets after cutting the tubes by cold deformation of about 80-90% with yield point and flexibility characteristics simultaneously rising at high plasticity maintained. After resistance spot welding of subchannels to each other and to rim spacer grids are not given thermal treatment. Tubes are annealed at T = 860-890 C for 40-45 minutes at residual pressure P = 0.002 mm Hg. At same pressure they are cooled down to T = 100-120 C followed by air cooling. EFFECT: enhanced quality of space grid manufacture. 2 cl, 2 dwg