SPACER-GRID ELEMENT AND ITS MANUFACTURING PROCESS Russian patent published in 1998 - IPC

FIELD: spacer grids of fuel assemblies. SUBSTANCE: process involves manufacture of internal and external strips of grid element with set of blades and set of springs. Strips are transferred by means of controlled conveyers. For centering the strips, holes are made in piercing die. Then strip is centered in each die and deflecting blades are shaped in blanking die, bent to acquire deflecting shape in bending die, and flexible springs are made in drawing die. After that, external strips are centered in bending die and bent to make each pair of strips into trihedral shape in cross-sectional area. All procedures are computer-aided. Then internal strips are joined together to form rhomboid rod cells receiving fuel rods and blind tubes, and external strips are joined by means of laser welding apparatus to form hexahedron. Structures formed by external and internal strips are joined together by means of laser welding apparatus. Spacer-grid element has two intersecting groups of sets of internal strips placed crosswise inside closed external strip and attached through their ends to external strip to form, when intersecting, set of rod cells to receive respective sets of fuel rods and blind tubes. Spacer-grid element has deflecting means coupled with each rod cell and provided in external and internal strips to deflect component of liquid current at fuel rods. It also has set of springs coupled with fuel rods and built up of members of internal and external strips for engaging respective fuel rod. Spacer-grid element is hexagonal in cross-sectional area. Rod cells are of rhomboid shape. EFFECT: improved reliability of spacer-grid element. 10 cl, 15 dwg