Nozzle dam remote installation system and technique

• US 5,006,302 A
• Filed: 04/19/1990
• Issued: 04/09/1991
• 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:
  US07/511,118
• Time in Patent Office: 355 Days
• Field of Search: 376/260, 376/204, 376/203, 376/277, 376/463, 29/906, 29/723, 29/726, 29/428, 29/890.31, 165/71, 165/76, 165/11.2, 138/89, 138/93, 122/379, 220/232, 220/233, 220/262, 49/506, 49/477, 277/1, 277/135, 254/413, 254/415, 254/389
• US Class Current: 376/260
• 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 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. An improved method for remotely translocating nozzle dam means from outside a nuclear reactor steam generator channel head to coupled association with nozzle holddown ring means within said channel head to thereby eliminate, or at least substantially minimize personnel exposure to radiation and/or radioactive contamination environment within said channel head, which improved method comprises the steps of:

(a) predeterming a first situs on the tubesheet associated with a nuclear reactor steam generator channel head;

(b) introducing into said nuclear reactor steam generator channel head, through a manway provided in the wall thereof, tubesheet tackle means, said tubesheet tackle means predisposed for operative association with first lifting means and said first lifting means in turn operatively associated with second lifting means, said second lifting means located juxtaposed a second situs, said second situs located outside of said channel head;

(c) remotely attaching said tubesheet tackle means to said first predetermined situs on said tubesheet;

(d) operatively associating nozzle dam strapping means with nozzle dam means and introducing the resulting assembly, with said nozzle dam means in folded mode, through said manway and into said channel head;

(e) operatively associating said nozzle dam strapping means with said first lifting means;

(f) actuating said second lifting means in a manner so as to apply at least an upwardly directed vertical force vector on that portion of said first lifting means juxtaposed said nozzle dam strapping means to elevate said folded nozzle dam means and effect the unfolding thereof to the full open position and continuing the actuating of said second lifting means in a manner so as to effect movement of said fully opened nozzle dam until the center point thereof is substantially vertically above the center point of said nozzle holddown ring and in juxtaposition therewith;

(g) remotely disengaging said nozzle dam strapping means from operative association with said nozzle dam;

(h) remotely effecting a determination of the proper orientation of said nozzle dam in relation to said nozzle holddown ring;

(i) remotely securing, at least temporarily, said nozzle dam means to said nozzle holddown ring;

(j) introducing into said nuclear reactor steam generator channel head, through said open manway, nozzle dam center section means and remotely operatively associating same with both said first lifting means and at least a portion of said nozzle dam strapping means for effecting subsequent positioning and engagement of said center section means with said at least temporarily secured nozzle dam means;

(k) remotely securing, at least temporarily, said nozzle dam center section means to said nozzle holddown ring; and

(l) introducing into said channel head suitable torquing means for securing said nozzle dam means to said nozzle holddown ring.

2. The improved method of claim 1 wherein steps (d) through (e) are sequenced (e) and (d).

3. The improved method of claim 1 wherein after step (g) thereof said nozzle dam is remotely rotated approximately 90 degrees prior to the determination of the proper orientation thereof in step (h).

4. The improved method of claim 3 wherein said approximate 90-degree rotation of said nozzle dam is effected by the actuation of nozzle dam rotation tool means in operative association with said nozzle dam.

5. The improved method of claim 1 wherein the location of said first predetermined situs is generally vertically above about the center point of the nozzle holddown ring located within said channel head.

6. The improved method of claim 1 wherein the introducing of said folded nozzle dam means through said open manway and into said channel head in step (d) thereof is effected with the aid of at least said first lifting means in operative association with tubesheet tackle means attached to said tubesheet at a third situs, said third situs generally located vertically above the center line of said manway.

7. The improved method of claim 1 wherein the introduction through said manway and into said channel head of said tubesheet tackle means in step (b) thereof is remotely effected with the aid of tackle insertion tool means.

8. The improved method of claim 7 wherein manipulation of said tackle insertion tool means is effected from about said second situs.

9. The improved method of claim 4 wherein one end of nozzle dam rotation tool means is introduced, from about said second situs, through said manway for attachment to said positioned nozzle dam and for remotely effecting said rotation.

10. The improved method of claim 1 wherein the remotely effecting of a determination of the proper orientation of said nozzle dam in relation to said nozzle holddown ring in step (h) thereof is remotely effected with the aid of alignment pin tool means introduced through said manway from about said second situs.

11. The improved method of claim 1 wherein the remotely effecting of a determination of the proper orientation of said nozzle dam in relation to said nozzle holddown ring in step (h) thereof is remotely effected with the aid of tubesheet mounted video camera means introduced through said manway from about said second situs.

12. The improved method of claim 1 wherein said remotely securing, at least temporarily, of said nozzle dam means to said nozzle holddown ring in step (i) thereof is effected with the aid of bolt starting tool means introduced through said manway from about said second situs for engagement with predetermined bolts on said nozzle dam means.

13. The improved method of claim 1 wherein the remote operatively associating of said nozzle dam center section means with at least a portion of said nozzle dam strapping means, or said first lifting means, or both is effected with the aid of hook pole means.

14. The improved method of claim 1 wherein effecting the engagement of said center section means with said at least temporarily secured nozzle dam means in step (j) thereof is effected with the aid of bolt starting tool means introduced through said manway from about said second situs for engagement with predetermined bolts on said center section means.

15. The improved method of claim 13 wherein said strapping means and said pole means are removed from said channel head prior to the introduction of said suitable torquing means.

16. The improved method of claim 1 wherein the introduction into said channel head of suitable torquing means for securing said nozzle dam means to said nozzle holddown ring in step (1) thereof also effects the securing of said center section means to said nozzle holddown ring means.

17. The improved method of claim 16 wherein subsequent to the securing of said nozzle dam means and said center section means the converse of said improved method is effected by the additional steps of:

(1) disengaging said center section means from nozzle holddown ring means;

(2) operatively associating said resulting disengaged center section means with said lifting means to effect translocation of said center section means to the general location of said open manway and thereafter providing for the egress of said center section means through said open manway;

(3) disengaging said nozzle dam means from said nozzle holddown ring means;

(4) operatively associating, at least one set of straps comprising said strapping means with a first and a second connecting means provided on said nozzle dam means, said first and said second connecting means juxtaposed the fold line of said nozzle dam means and predisposed on opposite sides and ends thereof whereupon the subsequent upward vertical forces exerted on said first and said second connecting means through said strapping means causes said nozzle dam means to seek a folded mode; and

(5) translocating the nozzle dam means in folded mode resulting from the operation of step (4), supra, to the general location of said open manway, and thereafter providing for the egress of said nozzle dam means in resulting folded mode through said open manway.

18. The improved method of claim 17 wherein tube sheet tackle means is attached to said tube sheet at a situs generally above the open manway after the operative connection of said tube sheet tackle means with said first lifting device and prior to the effecting of step (1) therein.