Patent Number: 05999584&
Section: summary

BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention relates generally to rigging components used for lifting heavy objects and, more particularly, to a system for rigging components for the heads of nuclear reactor vessels. (2) Description of the Prior Art Nuclear reactor vessel heads must be lifted and removed periodically to perform scheduled or corrective maintenance. Also, the reactor internals may need to be lifted at the same time for similar reasons. Currently, lifting either of these components requires up to four rigging changes during a typical reactor outage. These changes are required because some reactor components must be lifted using a combination of turnbuckle pendants, solid rod lifting pendants, and/or bridge strands, while others must be lifted using latchbox pendants, solid rod lifting pendants, and/or bridge strands. The changeover between these rigging components requires a large amount of time and manpower. It should be understood that the components being lifted are quite heavy, in some cases over 20 tons. Thus the rigging components are massive in size and require a great deal of time to change out. The time factor is important because increasing the time required to remove components increases personnel radiation exposure and the total time that a reactor must be out of service for maintenance/repair. Because the above-mentioned components are difficult to maneuver, each requirement for a rigging change increases the chance of personnel injury. Considerable cost-savings can be achieved and the chances for personnel injury may be reduced by reducing the number of rigging changes required for each lift. However, because of the capital expenditures restraints all utilities must live with, the cost of the rigging conversion must be relatively low. Thus, there remains a need for a new and improved rigging system for nuclear reactor components that reduces the number of rigging changes required during a reactor outage while, at the same time, is easy to add to the existing rigging system. SUMMARY OF THE INVENTION The present invention is directed to a rigging system for reactor closure head and reactor internals lifts. The system includes a plurality of latchbox pendants attached to the lifting structure of an overhead crane. A first set of a plurality of lifting lugs is attached to the reactor internals, each of the lifting lugs corresponding to one of the plurality of latchboxes. A second set of a plurality of substantially identical lifting lugs, each of the lifting lugs corresponding to one of the plurality of latchboxes, is attached to a plurality of solid rod lifting pendants attached at one end to the reactor closure head. In the preferred embodiment, adjustable turnbuckles are attached between each of the substantially identical lifting lugs and the plurality of solid rod lifting pendants attached to the reactor closure head. In operation, the latchbox pendants may be rigged once to the overhead crane for handling reactor internals and left in place throughout the entire rigging sequence without changing to turnbuckle pendants for reactor closure head handling. Accordingly, one aspect of the present invention is to provide a rigging system for reactor closure head and reactor internals lifts. The system includes: (a) a plurality of latchbox pendants attached to the lifting structure of an overhead crane; (b) a first set of a plurality of lifting lugs attached to the reactor internals, each of the lifting lugs corresponding to one of the plurality of latchboxes; and (c) a second set of a plurality of substantially identical lifting lugs attached to the reactor closure head, each of the lifting lugs corresponding to one of the plurality of latchboxes; whereby the latchbox pendants may be rigged once to the overhead crane for handling reactor internals and left in place throughout the entire rigging sequence without changing to turnbuckle pendants for reactor closure head handling. Another aspect of the present invention is to provide a conversion kit for an existing rigging system for reactor closure head and reactor internals lifts, the existing rigging system including a plurality of latchbox pendants attached to the lifting structure of an overhead crane and a first set of a plurality of lifting lugs attached to the reactor internals, each of the lifting lugs corresponding to one of the plurality of latchboxes. The conversion kit includes: (a) a second set of a plurality of substantially identical lifting lugs attached to the reactor closure head, each of the lifting lugs corresponding to one of the plurality of latchboxes; and (b) a plurality of adjusting means attached between each of the substantially identical lifting lugs and the reactor closure head, whereby the latchbox pendants may be rigged once to the overhead crane for handling reactor internals and left in place throughout the entire rigging sequence without changing to turnbuckle pendants for reactor closure head handling. Still another aspect of the present invention is to provide a rigging system for reactor closure head and reactor internals lifts. The system includes: (a) a plurality of latchbox pendants attached to the lifting structure of an overhead crane; (b) a first set of a plurality of lifting lugs attached to the reactor internals, each of the lifting lugs corresponding to one of the plurality of latchboxes; and (c) a second set of a plurality of substantially identical lifting lugs attached to the reactor closure head, each of the lifting lugs corresponding to one of the plurality of latchboxes; (d) a plurality of solid rod lifting pendants attached at one end to the reactor closure head; and (e) a plurality of adjusting means attached between each of the substantially identical lifting lugs and the plurality of solid rod lifting pendants attached to the reactor closure head, whereby the latchbox pendants may be rigged once to the overhead crane for handling reactor internals and left in place throughout the entire rigging sequence without changing to turnbuckle pendants for reactor closure head handling. These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.