Supports – Brackets – Specially mounted or attached
Reexamination Certificate
1999-04-07
2001-02-06
King, Anita M. (Department: 3632)
Supports
Brackets
Specially mounted or attached
C376S249000, C248S647000
Reexamination Certificate
active
06182932
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to an apparatus for use in performing inspections of a nuclear power plant steam generator. More particularly, the invention relates to a moveable apparatus that supports an anchored leg and a robot arm for inspecting a nuclear power plant steam generator, wherein the device automatically or manually repositions the manipulator arm.
BACKGROUND OF THE INVENTION
Steam generator (S/G) inspections and repairs are a major component of the aging commercial pressure water reactor (PWR) nuclear industry refueling outage duration. As power producers enter the deregulated market, the need to shorten outage duration, dose and cost is more important than ever. Steam generator inspections are a high-end technology, which is constantly changing, and are a major portion of each unit's outage cost. The work occurs in the primary system, which is one of the highest radiation areas in the plant. The speed at which a S/G inspection is conducted is critical to decreasing the outage duration, dose and cost. These metrics are used by the nuclear industry to measure efficiency, planning, compliance and control during outages.
Existing S/G inspection systems include a leg anchored to a tube sheet. The leg provides vertical motion for a three-axis arm to facilitate the required inspections and repairs. During S/G inspections, the manipulator arm must be repositioned relative to the S/G plenum to access the entire surface of the tube. This repositioning of the manipulator arm adds time, dose and significant preplanning to minimize the number of moves required during the inspection/repair campaign.
Generally, two platform workers located outside the S/G reposition the manipulator arm using a block and tackle and long poles. Whenever the manipulator is repositioned, the potential for robot damage is significantly increased due to the fact that the manipulator arm must be removed from the S/G plenum prior to repositioning and re-installed after repositioning is complete. Additionally, during an inspection, it is vital to maintain the arm parallel with the tube sheet for proper operation of various tooling. Frequently, platform workers are required to straighten the leg during repair activities to keep the arm straight.
Consequently, there is a need for a S/G inspection system that permits repositioning of a S/G manipulator arm without having to remove the arm from the anchored leg. Additionally, there is a need for a S/G inspection system that facilitates repositioning both the anchored leg and manipulator arm relative to the S/G.
SUMMARY OF THE INVENTION
In overcoming the shortcomings of the prior art systems, a main object of the invention is to provide a flexi-rail assembly that includes a housing; at least one lock assembly carried by the housing for coupling the housing to a support structure; and a carriage assembly movably supported by the housing for supporting and positioning inspection tools such as a robot manipulator arm and leg assembly.
The housing is generally mounted on a stay cylinder, and thus the surfaces forming the housing have a slight curvature to permit the housing to rest substantially flush with the stay cylinder; however, a small gap between housing and the stay cylinder is not detrimental to the operation of the flexi-rail assembly. The housing includes a hollow rear portion for receiving at least one cylinder supporting a movable surface, wherein the cylinder is coupled to a source of pressurized fluid. The housing also supports at least one recessed surface for receiving the lock assembly.
The lock assembly includes the cylinder (discussed above) and at least one tubular member. The tubular member includes an open center and at least two openings in the surface tubular structure. The lock assembly also includes a shaft received in the open center, the shaft defining at least two recessed surfaces. Each recessed surface supports at least one ball sized to be received in the openings defined by the tubular member, wherein a portion of each ball contacts a portion of the shaft and an adjacent external surface when received in the openings. This arrangement couples the housing to the external surface when the balls are forced off the recessed surfaces and into the openings defined by the tubular member. This action wedges the balls between the shaft and the external surface.
The carriage assembly includes a first surface supporting a plurality of outwardly projecting cylindrical members for coupling the carriage assembly to the housing; a second surface carried by the first surface, the second surface supporting a plurality of cylindrical members for coupling the carriage assembly to the housing; and a third surface movable relative to the second surface, the third surface supporting a locking assembly for securing the third surface to the housing.
Specifically, the flexi-rail assembly includes an apparatus for supporting and positioning tools for inspecting a nuclear power plant steam generator. The apparatus includes a housing; at least one tube lock assembly carried by the housing for coupling the housing to a tube sheet, and a carriage assembly.
The housing includes front, rear, top, bottom, and side wall surfaces. The housing has a slightly curved surface, and supports a cylinder (discussed below) which forms part of the lock assembly.
The tube lock assembly includes the cylinder (discussed above) and three locking members. The cylinder supports a movable surface, and is coupled to a source of pressurized fluid using known techniques. As the pressurized fluid enters the cylinder, the movable surface extends. A link, an elongated member, couples the movable surface to the tube locking members.
Each tube locking member is a tubular structure having an open center and at least two openings formed in the surface of the tubular member. A shaft is received in the open center of the tubular structure. The shaft defines at least two recessed surfaces, each recessed surface supporting at least one ball sized to be received in the openings defined by the tubular member. The balls rest in the openings such that a portion of each ball contacts a portion of the shaft and an adjacent surface of the tube sheet when received in the openings. This arrangement couples the housing to the tube sheet when the balls are forced off the recessed surfaces and into the openings defined by the tubular member, wherein each ball is wedged between the shaft and the adjacent surface of the tube sheet surface.
The engagement between the shaft, balls and the tube sheet is reinforced by a spring pressure. The shaft is coupled to a spring for inducing a downward load on the shaft, forcing the balls to remain in the openings and wedged against the shaft and the external surface.
The apparatus also includes a carriage assembly movably supported by the housing for supporting and positioning inspection tools. The carriage assembly includes a first surface supporting a plurality of outwardly projecting cylindrical members for movably coupling the carriage assembly to the housing; a second surface carried by the first surface, the second surface supporting a plurality of cylindrical members for movably coupling the carriage assembly to the housing; and a third surface movable relative to the second surface, the third surface supporting a block locking assembly for securing the third surface to the housing.
The block locking assembly includes a plurality of tubular members retained in a block housing, the tubular members being coupled to a source of pressurized fluid; and a ball-detent system retained by each tubular member. The ball-detent system is identical to that previously described, and thus includes a tubular member having an open center and at least two openings in the surface of the tubular member; and a shaft received in the open center. The shaft has at least two recessed surfaces formed in opposite faces. Each recessed surface supports at least one ball sized to be received in the openings defined by the tubular member. A portion of each ball
CE Nuclear Power LLC
Crenshaw Henry T.
DeLuca Jerome
Kananen Ronald P.
King Anita M.
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