Patent Number: 042696615
Section: abstract

A top nozzle for a nuclear reactor fuel assembly which includes an orifice plate designed to receive control rod guide tubes extending upwardly from the top of the fuel assembly. Nozzle pin extensions connected to the orifice plate are axially coextensive with the guide tubes and project upwardly through a top nozzle hold-down plate, and through openings in the upper core plate in the reactor. The hold-down plate is spring biased into an upper core plate engaging position and since the pin extensions are adapted to move in the core plate and against the action of the springs, the top nozzle thus becomes effective in accommodating upwardly acting hydraulic forces which tend to lift the fuel assembly, and to accommodate differential expansion of parts in the fuel assembly as compared to the core barrel in which the assembly is located. The number of pins disposed in the hold-down plate move in slots formed in each of the guide tube extensions and the uppermost position of the fuel assembly is determined when the pin is in the bottom of its slot in each of the guide tubes.