Benedict Kazirskis - Barto PA Edward L. Wrobel - Pottstown PA
Assignee:
General Electric Company - San Jose CA
International Classification:
G21C 1920
US Classification:
376260
Abstract:
A low-headroom tower is pivotably mounted to a trunnion cart that runs on rails in a slot in a work platform located in the sub-pile room of a reactor containment. An elevator in the tower raises an extension piece into contact with the bottom of a control rod drive. A detorquing guide is rotationally positioned to coincide with bolts holding the control rod drive in place. The elevator places an upward force on the control rod drive during detorquing of the bolts. This provides reaction torque to aid in bolt loosening and prevents leakage of contaminated effluent past the seal. A detorquing tool is fitted into the detorquing guide and is spring loaded to engage a selected bolt securing the control rod drive. An indexing device provides alignment for the detorquing tool with each succeeding bolt. The elevator is lowered until the bottom end of the control rod drive enters the tower.
An apparatus and method for removing and installing a control rod drive includes a first chain and a second chain. Each chain has a plurality of links, which have a pivotable portion and a rigid portion, for allowing the first chain to bend in a single direction and the second chain to bend in a single direction. The rigid portion of the second chain is positioned adjacent to and contacts the rigid portion of the first chain for providing a rigid column. An end block retains the first ends of the first and second chains and a drive mechanism draws the first and second chains through the drive mechanism, for moving the control rod drive. The control rod drive handling equipment may also include at least one first, at least one second, and at least one third chain guide for supporting the first and second chains, at least one wheel attached to the second chain guide, and a plurality of pins positioned through apertures of adjacently positioned links of the first and the second chains. The method may include introducing the first and the second chains through an access hole in the vessel support structure of a boiling water reactor and moving the control rod drive handling equipment along a track positioned in an undervessel area of the reactor for aligning the control rod drive handling equipment with a control rod drive.
A method for moving equipment wherein a first chain which is free to bend in only one direction and a second chain which is free to bend in only one direction are positioned adjacent each other so that the two bend directions are opposed one another to form a rigid column. The equipment, which may include control rod drive handling equipment for a boiling water reactor, is attached to the rigid column. The equipment may be moved by moving the rigid column through a drive mechanism.