Nozzle dam remote installation system and technique

• US 4,989,818 A
• Filed: 04/19/1990
• Issued: 02/05/1991
• Est. Priority Date: 06/13/1989
• Status: Expired due to Fees

• Current Assignee: Lifecore Biomedical Incorporated
• 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:
  US07/511,167
• Time in Patent Office: 292 Days
• Field of Search: 376/260, 376/463, 294/86.25, 294/82.28, 294/89, 294/93, 294/94, 294/87.1, 294/87.11, 294/81.6, 294/906, 122/DIG. 14, 279/2 R, 279/22, 279/75, 165/76, 29/523, 403/322, 403/374, 411/348, 248/332, 248/327, 248/231.9
• US Class Current: 248/332
• 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
• CPC Class Codes: Y10T 403/7064 by wedge or cam

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 or said nozzle dam means, torquing bolting means to predetermined limits; and removing from said channel head all said attendant tubesheet tackle means. The effecting of the instant technique requires only a minimal amount of relatively inexpensive, but specially 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. In an improved device for gripping and cooperatively engaging a plurality of tubes of substantially equal inner diameters, said improved device including shaft means, said shaft means including a tapered upper portion, a generally cylindrical lower portion, and an intermediate neck portion;

cylindrical sleeve means, said cylindrical sleeve means being spaced around said shaft means and including at least two apertures generally opposite said tapered portion of said shaft means, the outer diameter of said cylindrical sleeve means being less than the inner diameter of said tubes;

resilient means operatively connected between said shaft means and said sleeve means for biasing relative longitudinal motion between said shaft means and said cylindrical sleeve means;

locking means arranged for operative association with each of said apertures, said locking means arranged for operative association with said tapered upper portion and the inner surface of one of said tubes, and each said locking means comprising a spherical-shaped member of material being substantially nondeformable relative to said tubes and having a diameter such that longitudinal motion of said cylindrical sleeve means relative to said shaft means causes said tapered portion to contact each of said locking means while said locking means protrude outside the surface of said cylindrical sleeve means; and

stop means generally disposed near the lower end of said cylindrical sleeve means and arranged for limiting the sleeve insertion into said tubes, the improvement in combination therewith which comprises;

(a) sleeve engagement means disposed near the lower portion of said cylindrical sleeve means and projecting away from the outside surface thereof, and said sleeve engagement means disposed vertically above later mentioned plate means;

(b) plate means associated with said generally cylindrical lower portion of said shaft means, said plate means disposed generally perpendicular to said shaft means and arranged to provide that at least a portion of said generally cylindrical lower portion of said shaft means projects both upwardly and downwardly from said plate means;

(c) at least two tube insertion pin means associated with said plate means and projecting upwardly therefrom, the outer diameter of said pin means being less than the inner diameter of said tubes; and

(d) load attaching means associated with said plate means and projecting downwardly therefrom.

2. The device of claim 1 wherein said shaft means and said at least two tube insertion pin means are predisposed in association with said plate means to be substantially coincident with said tubes.

3. The device of claim 2 wherein there are two pin means in predisposed association with said plate means.

4. The device of claim 3 wherein the sleeve engagement means disposed near the lower portion of said cylindrical sleeve means and projecting away from the outside surface thereof is provided with an aperture.

5. The device of claim 4 wherein said cylindrical sleeve means includes a rigidly connected cap and said resilient means includes a longitudinally oriented spring interposed between said cap and the upper end of said upper tapered portion of said shaft means.