NUCLEAR REACTOR FUEL ASSEMBLY Russian patent published in 1997 - IPC

FIELD: nuclear reactors. SUBSTANCE: fuel assembly has bundle of fuel elements vertically installed in frame built up of spacing grids mounted on tubular channels. Inserted in the latter are absorbing robs suspended from yoke with head. Bundle of fuel elements has top and bottom shanks and removable head. The latter has bottom supporting plate and top carrying plate, both having holes and mounted on guide bushes easily passed through mentioned holes with radial clearance. Guide bushes are provided with collet grips at bottom part embracing bosses on tubular channels by their drillings and installed through their inner steps on ends of tubular channels. Assembly head has springs mounted coaxially to guide bushes between top carrying plate and supporting disks resting on external projections of guide bushes, central spring partially compressed between bottom supporting plate and top carrying plate. Guide braces secured in bottom supporting plate pass with radial clearance through hole in top carrying plate. Bosses on top ends of guide bushes limit upward displacement of top carrying plate. Stop plate is rigidly coupled through conical shell to bottom supporting plate with holes embracing collet guides in the vicinity of drillings. Cylindrical shell with keys is joined with top carrying plate. Thrust bush mounted on bottom supporting plate along fuel assembly axis has internal step arranged with axial clearance above top end of central tubular channel. EFFECT: improved design. 5 cl, 12 dwg