General Electric Company

Peter A Peterson

Russell Patrick Higgins

Bob Y Okashima

Gary I Borchardt

A method and an apparatus for locking the tie rods to block rotation relative to either the upper or lower tie plates utilizing the required fuel bundle channel. A conventional lock nut is provided for threading to the upper threaded end of the tie rods. This lock nut has attached extending wings, these wings when rotated interfering with a placed fuel bundle channel. In installation to the fuel bundle, and assuming that the tie rod has been fully threaded to the lower tie plate, the winged lock nut is rotated overlying the upper tie plate to cause full engagement of the upper tie plate to the tie rods. In such fastening, the winged lock nuts are rotated to an angle that provides no interference with the subsequently placed channel. Thereafter, and when the channel is placed, the channel interference with the rotational path of the wings of the lock nut and thus prevents relative rotation between the tie rod and winged lock nut. The fastening of the wings to the lock nut leaves portions of the hex surface of the lock nut exposed. Thus when bundle disassembly is required, only removal of the channel followed by conventional counter or unthreading rotation of the winged lock nut with sufficient force to overcome the locking characteristic of the nut is required. Consequently, disassembly for inspection of an irradiated fuel bundle assembly is facilitated.

Self locking nut for fuel assembly tie rods

A part length fuel rod tip and group of tip grasping tools is set forth for the removal, inspection and replacement of part length fuel rods from a fuel bundle having a part length rods interspersed with a majority of conventional full length rods. The part length fuel rod tip includes a longitudinal keyway allowing torque to be exerted on the fuel rod and a horizontal slot enabling grasping of the fuel rod for vertical withdrawal and replacement movement of the fuel rod. The tools include a torque socket for applying high torque forces to the part length rod for unscrewing the rod when the rod becomes stuck at its threaded connection to the lower tie plate, a tip grasping tool for permitting normal unscrewing torque and grasping for vertical withdrawal and replacement, and finally a tool having both high torque and grasping characteristics. In each case, the diameter of the tools is restricted to enable access to the part length fuel rods through the spacers overlying the upwardly exposed ends of the part length fuel rods.

Growing community of inventors

San Ramon, CA, United States of America

Peter A Peterson