US 5,006,302 AGranted

Nozzle dam remote installation system and technique

AssigneeTennessee Valley Authority

InventorsMark H. Trundle, William C. Jones

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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.

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.

10 more elements

Facts

Application

07/511,118Filed 19 Apr 1990 · division

Priority

13 Jun 1989

Granted

9 Apr 1991

Term ends

Not estimatedThe source records don’t support an estimate.

Classification7 codes

F22B 37/003
Specially adapted for nuclear steam generators, e.g. maintenance, repairing or inspecting equipment not otherwise provided for: maintenance,…
F22B 37/222
Covers for drums, collectors, manholes or the like: nozzle dams introduced through a smaller manway, e.g. foldable
G21C 13/067
Sealing-plugs: for tubes, e.g. standpipes; Locking devices for plugs
Y02E 30/30
Energy generation of nuclear origin: nuclear fission reactors

Abstract

Claims18