General Electric Company

Carl R Mefford

Eric B Johansson

Robert B Elkins

Thomas G Dunlap

James E Cearley

Michael V Curulla

Jaime A Zuloaga, Jr

Harold L Nelson

William G Jameson, Jr

Jerry T Spell

Leaf-type springs are inserted into slots in an upper tie plate of a nuclear fuel assembly and bear against interior surfaces of the fuel channel to center the upper tie plate within the fuel channel. More robust similarly configured leaf springs are secured in slots in the upper tie plate and are cantilevered for bearing engagement through slots in the fuel assembly channel against the reactor top guide to bias the fuel assemblies toward the control rod. To mount each spring to the upper tie plate, the base of each leaf spring includes a central beam and a pair of outermost beams spaced from the central beam, all beams lying in a common plane. Laterally outwardly directed tabs are provided on the lower ends of the outer beams. Stops are provided intermediate the ends of the outer beams. By inserting the unstressed, unloaded base of the springs into the slots, the outer beams are displaced inwardly into a stressed condition. Once the tabs extend past the lower surface of the tie plate, the beams return to an unloaded, unstressed condition with the tabs and stops locking the springs to the tie plate. The distal ends of the springs bear against the channel or top guide, as applicable, to locate the upper tie plate within the channel and bias the fuel assembly and channel toward the control rod, respectively.

Spring retention of upper tie plate and fuel bundle channel in a nuclear

In a nuclear fuel assembly having a coolant conducting or water tube which also retains the spacers in axial position, the fuel rods experience greater axial growth with exposure than the water tube creating a risk that the water tube might become disengaged from the supporting tie plates. An arrangement for preventing such disengagement is described including lengthened end plug shanks for the water tube, a protective boss surrounding the lower end plug shank to protect it from flow induced vibration, a conical seat for the lower end plug and an arrangement for limiting upward movement of the water tube.

Nuclear fuel assembly with coolant conducting tube

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Los Gatos, CA, United States of America

Carl R Mefford