NUCLEAR REACTOR FUEL ASSEMBLY Russian patent published in 2004 - IPC

FIELD: nuclear power engineering; nuclear reactor fuel assemblies. SUBSTANCE: fuel assembly of water-cooled power reactor incorporates bundle of fuel elements vertically mounted in frame of spacer grids secured on tubular channels and made in the form of field of shaped subchannels welded together at points fastened outside by means of interconnected composite parts in the form of rim with coolant baffles acting from periphery to center, lower spacer grid, bottom nozzle, and removable top nozzle. Bosses are provided on edges of spacer grid rim inclined to each other through 120 deg, boss height being equal to half the width of clearance between fuel assemblies and reactor core. Adjacent edges of spacer grid rim tilted through 120 deg. to each other are provided with bosses whose height is found from formula Hb2 - S - S1 - Hb1, where Hb2 is variable height of boss; S is fuel assembly pitch in reactor core; S1 is actual key-turn size of spacer grid at pair of edges free from bosses; Hb1 is permanent height of boss; Hb1 = const = 1/2 of clearance δ between fuel assembly and reactor core. Quantity of bosses is sufficient to eliminate curvature of fuel assembly within core and to afford additional intermediate supports taking horizontal thrusts upon full assembly of reactor core. EFFECT: enhanced stiffness, operating reliability, safety, manufacturability, and manufacturing precision of fuel assembly. 2 cl, 3 dwg