Nozzle dam remote installation system and technique

• US 5,042,861 A
• Filed: 04/19/1990
• Issued: 08/27/1991
• Est. Priority Date: 06/13/1989
• Status: Expired due to Fees

• Current Assignee: Tennessee Valley Authority (Government of the United States of America)
• Original Assignee: Tennessee Valley Authority (Government of the United States of America)
• Inventors: Jones, William C., Trundle, Mark H.
• Primary Examiner(s): Wasil, Daniel D.
• Application Number:
  US07/511,120
• Time in Patent Office: 495 Days
• Field of Search: 376/260, 269/1, 269/2, 269/3, 269/6, 269/289 R, 7/167, 29/723, 29/726, 414/741, 414/738, 294/19.1
• US Class Current: 294/164
• CPC Class Codes: F22B 37/003 Maintenance, repairing or inspecting equipment positioned in or via the headers
• CPC Class Codes: F22B 37/222 Nozzle dams introduced through a smaller manway, e.g. foldable
• CPC Class Codes: G21C 13/067 for tubes, e.g. standpipes; Locking devices for plugs
• CPC Class Codes: Y02E 30/30 Nuclear fission reactors

Abstract

The present invention relates to a system, teaches a technique, and provides apparatus eminently useful for the installation/removal, from a remote and protected location, of nozzle dams onto and from nozzle holddown rings within the channel heads of certain steam generators, including the types typically used in conjunction with the operation of pressurized hot-water nuclear power plants. The technique or method of the instant invention involves methodology for remotely introducing usually with the aid of tackle insertion tool means, through an open channel head manway requisite tubesheet tackle means, or tackle means, as well as strapping means and the securing of same therein; inserting through said open manway, usually with the aid of lifting means, folded nozzle dam means; opening said dam means and properly orientating same relative to said nozzle holddown ring; inserting, orientating, and securing the center portion of said nozzle dam means, torquing bolting means to predetermined limits; and removing from said channel head all said attendant tubesheet means. The effecting of the instant technique requires only a minimal amount of relatively inexpensive, but specifically designed equipment and is simply, quickly, and easily placed into practice by, for example, manipulation of same by one or more human operators who are physically located outside said channel head(s) and adjacent said open manway thereby substantially reducing the effective radiation dose heretofore normally associated with such nozzle dam installation and removal.

Claims

1. A device for remote operative association with a tube gripper, said tube gripper predisposed for cooperatively engaging a plurality of tubes of substantially equal inner diameters and including plate means and sleeve attachment means, said device comprising:

(a) shaft means having a first end and a second end;

(b) connecting means traversing said shaft means substantially from said first end to said second end;

(c) actuating means disposed near said first end of said shaft means and operatively associated with said connecting means;

(d) first engaging means disposed near said second end of said shaft means and generally comprising a U-shaped member having one leg thereof substantially longer than the other, each of said legs comprising a plate member, the major planes of which are, in the intended mode of operation of said device, generally horizontal, with the bottommost plate member being the substantially longer leg and having a generally triangular-shaped opening therein, the base of said triangular-shaped opening being juxtaposed the edge of said lower plate member which is most remote from the U-portion of said first engaging means, the apex of said generally triangular-shaped opening terminating at a distance away from said U-portion approximately equal to the length of said shorter leg, and said plate members separated, one from the other, a distance greater than the thickness of said plate means for the accommodation into said U-portion and on said bottommost plate member of said plate means; and

(e) second engaging means juxtaposed said first engaging means and generally disposed vertically thereabove for operative association with both said sleeve attachment means and said connecting means.

2. The device of claim 1 wherein said second engaging means includes movable pin means for engagement with an aperture provided in said sleeve attachment means.

3. The device of claim 2 wherein resilient means is connected between said first engaging means and said second engaging means for biasing relative separation motion therebetween.

4. The device of claim 3 wherein stop means is provided to limit the movement of said movable pin means, in operative association with said connecting means, relative to said aperture and thereafter provide movement of said second engaging means toward said first engaging means and against the biased relative motion of said resilient means.

5. The device of claim 4 wherein said shaft means includes at least one aperture to provide for, substantially throughout its length, accommodation of said connecting means.