Abstract: A machine for smoothly and controllably winding or unwinding a stiff in-core-instrument tube onto and off of a reel during ythe refueling of a nuclear reactor. The machine includes a frame (33) and a circular reel (32) having a substantially continuous helical groove (44) extending around the circumference of the reel. The groove is adapted to receive the tube (14). A plurality of cam rollers (52) are carried by the frame and closely spaced around the circumference of the reel. The rollers keep the tube in the groove whereby the tube may be more easily wound onto or off of the reel. In the preferred embodiment, the reel carries a disposable cartridge (46) in which the grooves are formed.

Abstract: The invention provides a hold-down device which maintains a net downward force on a fuel assembly in a nuclear reactor under all thermal and hydraulic conditions in the reactor core region. The hold-down device is particularly applicable in reactors having stainless steel support barrels and Zircaloy guide tubes.The hold-down device of the preferred embodiment of the invention is comprised of coil springs coaxially disposed about alignment posts which extend upwardly from the top end plate of each fuel assembly. A hold-down plate is slideably mounted on the alignment posts and the coil springs are interposed, in compression, between the hold-down plate and the top end plate. In use, the coil springs bias the hold-down plate upwardly against a core alignment plate to provide a downward force on the fuel assembly. The hold-down plate may also serve as a lifting surface for the fuel assembly during fuel handling.