Tooling system for remote load positioning

A manually controlled tooling system for the remote placement and removal of a load, such as a plug, (12) at a location (6) inaccessible to maintenance personnel. The tooling provides for both horizontal and vertical movement of the load, and, in the preferred embodiment, rotational restraint. The load is supported vertically by at least one line (21) wrapped on a small diameter drum (19) which is supported from a travelling trolley (11) fitted to a sloping track (10). On the same shaft as the load drum, a large diameter centrally located sheave or control drum (20) accepts a single control line (13) counterwrapped in direction with respect to the load support line and terminating at its other end on a hand operated winch mechanism (14). The tooling acts to first allow the trolley to descend the track without relative motion between trolley and load. Then, with the trolley bottomed against a mechanical stop (26), the load is allowed to descend vertically to its desired position. Retrieval of the load is accomplished by reversal of the above steps resulting when the hand winch is reversed. Thus, two load motions in each direction are controlled by a single line without the need for separate, independent motion inputs. There is further disclosed a collapsable track and trolley system, as well as a method of assembly and operation, that is capable of passage through a narrow manway (7) for deployment in an elongated passageway or conduit (1).

BACKGROUND OF THE INVENTION 
This invention relates to remote load positioning, and more particularly to 
remote placement of a plug or similar article on a target within a 
manually inaccesible area of a nuclear power plant, such as primary system 
piping. 
In many pressurized water reactor piping designs, provision is made for 
auxiliary shutdown cooling loops to remove residual heat from the primary 
coolant once the reactor has been shutdown, depressurized, and the primary 
circulating pumps deactivated. Typically, such loops will draw coolant 
from a hot leg connecting a steam generator to the reactor vessel, pass 
the coolant through a heat exchanger, and return the lower temperature 
coolant to the reactor by means of one of the primary system cold legs. 
These loops are not used during normal reactor operation and are typically 
isolated from the system by valves. Past practice has allowed for pipe 
maintenance on shutdown cooling loops and their isolation valves by 
providing valves on the reactor hot and cold legs, and thus the shutdown 
coolant loops; or by physically locating shutdown coolant loop isolation 
valves above the level of reactor coolant needed for shutdown cooling, 
thus permitting valve maintenance or replacement without the loss of 
coolant necessary to maintain the reactor core at specified shutdown 
temperatures. 
For piping systems with none of the above provisions, a means is needed for 
isolating each of the shutdown coolant loops independently of other loops 
which provide the cooling function while the defective loop is repaired. 
One solution is to remove the reactor vessel head and the upper vessel 
internals, and to remove all the fuel assemblies comprising the reactor 
core to temporary fuel storage. In this case, the shutdown coolant loops 
are not needed and the loops may be drained of coolant to permit the 
necessary maintenance. This method is unacceptable to most reactor 
operators because of the time and cost to remove and replace the entire 
core which adds to the reactor's unavailability to produce useful energy. 
A second solution is to remove the reactor vessel head and the upper vessel 
internals. This condition allows access to the reactor vessel hot leg 
nozzles while the fuel assemblies are still in place in the reactor core. 
Remote tooling may then be utilized to sequentially plug each of the hot 
leg nozzles associated with shutdown coolant loops requiring maintenance. 
Such an operation would require the reactor plant to be placed in the 
refueling mode with the refueling pool flooded even if a refueling outage 
were not scheduled. 
A third solution is to install a plug in the branching nozzle of the hot 
leg which is used to draw coolant into the shutdown coolant loop. In this 
case, the reactor needs only to be placed in the shutdown mode, and the 
vessel head and internals may remain in place. The plug and tooling are 
entered into the drained steam generator primary head, assembled, and the 
plug installed in the branching nozzle by an operator manipulating the 
tooling described in this disclosure. 
SUMMARY OF THE INVENTION 
The present invention is directed to manually controlled tooling for the 
remote placement and removal of a load, such as a plug, at a location 
inaccessible to maintenance personnel. The tooling provides for both 
horizontal and vertical movement of the load, and, in the preferred 
embodiment, rotational restraint. The load is supported vertically by at 
least one line wrapped on a small diameter drum which is supported from a 
travelling trolley fitted to a sloping track. On the same shaft as the 
load drum, a large diameter centrally located sheave accepts a single 
control line counterwrapped in direction with respect to the load support 
line and terminating at its other end on a hand operated winch mechanism. 
The tooling acts to first allow the trolley to descend the track without 
relative motion between trolley and load. Then, with the trolley bottomed 
against a mechanical stop, the load is allowed to descend vertically to 
its desired position. Retrieval of the load is accomplished by reversal of 
the above steps resulting when the hand winch is reversed. Thus, two load 
motions in each direction are controlled by a single line without the need 
for separate, independent motion inputs. 
In the preferred embodiment, the invention is a device for transporting a 
load up or down an incline while maintaining that load in a vertical, 
plumb attitude with minimum rotation. The load is vertically translated 
relative to the trolley at a predetermined point along its travel on the 
incline. The translated and vertical motion are both controlled by a 
single control line. 
The invention further provides a collapsible track and trolley system, as 
well as a method of assembly and operation, that is capable of passage 
through a narrow manway for deployment in an elongated passageway or 
conduit. 
For a better understanding of the invention, its operating characteristics, 
and the specific benefits obtained by its use, reference should be made to 
the accompanying drawings and description which relate to a preferred 
embodiment as applied to the plugging of a branching nozzle in the piping 
constituting a part of the primary coolant loop between a nuclear reactor 
vessel and its associated steam generator.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 depicts a typical reactor primary coolant hot leg 1 connecting a 
reactor vessel 2 and the inlet plenum 3 of a steam generator. In the 
shutdown condition, the primary reactor coolant is drained to a level 4 
such that the reactor core 5 remains submerged and which provides a 
suction head for the shutdown cooling loop inlet nozzle 6. Under these 
conditions, the steam generator manway 7 may be removed for personnel and 
equipment access, and the defective shutdown coolant loop deactivated so 
that there is no flow through nozzle 6. Reactor cooling is provided 
through one or more of the other hot legs and associated shutdown cooling 
loops (not shown). 
The tooling consists of a support frame 8 which is secured to the steam 
generator nozzle 9 and a segmented track 10 which is assembled inside the 
steam generator and hung on support frame 8. An underhung trolley 11 is 
installed onto track 10 and a flanged nozzle plug 12 attached to the 
trolley 11 so as to hang in the vertical attitude. The vertical movement 
of plug 12 and travel of trolley 11 along track 10 are controlled by line 
13 connecting trolley 11 to hand winch 14 mounted at the top of the track. 
An end view cross section of the trolley 11 is shown in FIG. 2. It is 
composed of trolley frame 15 to which are cantilever mounted four roller 
means such as flanged trolley wheels 16 equipped with anti-friction 
bearings. These wheels engage track 10, which is constructed of a 
plurality of sections or segments, each preferably comprising two parallel 
channel-shaped members 17 connected by a series of structural members 18. 
Track members 17,18 in this figure are shown in phantom. Mounted in 
trolley frame 15 is a freely rotating double drum assembly consisting of 
two small diameter flanged drums 19 for load support and one larger 
diameter control drum or sheave 20 all fixed so that they turn as a unit. 
One end of two equal length load support lines 21 is fixed to a respective 
drum 19 by wrapping one line righthand and the other lefthand as shown. At 
the opposite end of support lines 21 are affixed safety snap hooks 22. 
Each hook engages a fitting 23 mounted on the plug 12. One fitting is 
adjustable so that the load hangs true and level if small differences in 
the length of support lines 21 exist. The use of two support lines dampens 
the tendency of load 12 to rotate about the vertical axis. A separate 
control line 13 is affixed to sheave 20 and wrapped in a counterclockwise 
direction with respect to support lines 21. The number of wraps of control 
line 13 is equal to or greater than the number of revolutions of drums 19 
to move the load 12 between its full up and full down positions, when the 
load is positioned over the target as shown in FIG. 1. Slideably 
adjustable line stops 25 bear on trolley frame 15 to establish the up 
limit position when control line 13 is pulled in the load raise mode. 
Support lines 21 pass through elongated slots 24 in the trolley frame 15 
and are so proportioned to prevent passage of line stops 25. 
For better understanding of the forces involved and the motions of trolley 
and load, reference is made to FIG. 3. Shown in schematic form is an 
inclined track 10 upon which rolls a trolley 11 of weight T. Load 12 has a 
weight designated as L and is supported by lines wrapped counterclockwise 
around small drums 19 of diameter, D.sub.1. Control line 13 is wrapped in 
a clockwise direction around large sheave 20 of diameter D.sub.2. Tensile 
force in line 13 is designated as F. Forces T, L, and F are the only 
forces acting on the system, with the exception of system friction, which 
for descriptive purposes may be assumed as negligible. 
Force F is composed of a torque component, F.sub.1, necessary to wind up 
load 12 until line stops 25 restrict its upward motion; and a travel 
component, F.sub.2, which must be added to cause trolley and load to move 
up the incline. The total tensile load in the control line is F=F.sub.1 
+F.sub.2 =(T+L) sin .theta.; the torque component is F.sub.1 =D.sub.1 
/D.sub.2 (L). Thus the condition which must be satisfied is given by: 
##EQU1## 
As control line 13 is winched up, trolley and load ascend the track 10. As 
it is paid out, trolley and load descend until the trolley bottoms on 
track stop 26. In this condition, the force in control line 13 necessary 
to prevent pay out of load 12 with respect to trolley 11 is equal to the 
torque component, F.sub.1. A reduction in tension in line 13 causes 
rotation of drums 19 and 20 and the vertical descent of load 12. 
As shown in FIGS. 1 and 3, once the load is at rest in its target location, 
tension in control line 13 is reduced to zero and the holding force at 
hand winch 14 disappears. Further rotation of the hand winch is prevented 
by a locking device (not shown) on the winch shaft. Plug and tooling may 
now be left in place with the tooling supported by a frame 8. The shutdown 
coolant loop may now be drained and the required maintenance performed. 
Load retrieval is essentially the reverse of load placement. Upon winching 
in of control line 13, an initial tension equal to F.sub.1, will cause the 
load to rise in the vertical until stops 25 restrict further motion. At 
this point, additional tension equal to F.sub.2 is applied via hand winch 
14 and load and trolley caused to disengage from track stop 26 and ascend 
the track. 
FIG. 4 illustrates the support frame 8 installed within nozzle ring 27 
which is a permanent part of steam generator nozzle 9 (See FIG. 1). The 
frame consists of two beams 28 which transversely span the inside diameter 
of the nozzle opening 29. Beams 28 are constructed of channel shaped 
structural members facing each other and accepting two cross members 30 
which are permanently pin connected to the beams by hinge pins 31. Thus, 
the beams and cross members form a collapsible hinged parallelogram which 
can pass through a manway and which, when installed, is held in place by 
the surrounding nozzle ring 27. A support bar 32 is captured by beam 
channels 28 and is slideably adjustable up or down, being held in place by 
threaded hand screws 33 which engage a plurality of locating holes 34 in 
each bean. Attached to support bar 32 are two support hooks 35 which 
engage cross members 18 of the track assembly. Thus the assembly of the 
track sections is facilitated and the assembled track can be located at a 
convenient elevation for operation of the remaining tooling. To the frame 
is also attached a removable load tray 36 which is supported by hinged bar 
37 and by the lower cross member 30. The tray provides a convenient shelf 
for supporting the load for its attachment 22 to the trolley. (See FIG. 
2). 
FIG. 5 depicts the segmented track 10 (see FIG. 1). It consists of a 
plurality of track segments, the basic structural members of each being 
two channel shaped tracks 17 spaced apart and held by a series of cross 
members 18. Segments are joined together by a pair of tongue plates 38 
which engage deep, narrow slots 39 in the mating segment. Segments are 
prevented from separating by hand operated latching means 40. 
FIG. 6 is an end view of the bottom of the track section to which is 
assembled a wheel assembly 41. This is a separate assembly to allow entry 
through manway 7. It is arranged to span shutdown inlet nozzle 6 during 
installation and removal of track section 10. Wheels are freely turning on 
their axle and are beveled to mate with the curvature of the inside of the 
pipe. Assembly 41 is keyed to tracks 17 by retainers 42 and held in 
position by a hand screw 43 captured in cross member 18. 
FIG. 7 is an end view of the top of the track section to which is 
permanently mounted winch drum 44 supported in bearings 45. Referring also 
to FIG. 1, control line 13 is threaded and anchored to this drum for 
equipment operation. Crank arm 46 and handle 47 control payout and payin 
as well as tension in the control line. By suitable positioning of crank 
arm and handle, trolley 11 shown in FIG. 1 may be assembled onto tracks 
17. Handle 47 is allowed to slide within arm 46 to allow passage of the 
assembly through the manway 7. 
FIG. 8 represents the component parts of the system and load, prior to 
insertion and deployment as shown in FIG. 1. Typically, the operator 
enters the steam generator 3 through manway 7, and an assistant remains 
outside to pass the components through the manway. 
The deployment procedure includes as the first step, passage of the support 
frame 8 through the manway, in a collapsed parallelogram configuration. 
The operator "squares up" the frame 8 transverse to the nozzle ring 27 (as 
shown in FIG. 4), then fastens the support bar 32 to the frame at a lower 
set of locating holes 34a to give the frame structural rigidity and to 
provide a support means for the inclined track member 10. 
Next, the bottom track segment 17a and wheel assembly 41 are passed through 
the manway and assembled by the operator in accordance with FIG. 6. The 
wheels are passed through the frame into rolling contact with the base of 
the nozzle 9, and the other end of track segment 17a, 18a is placed on 
hooks 35 on the support bar 32. 
Each additional track segment 17b, 17c, 17d is in turn mated with the 
preceeding segment as shown in FIG. 5, by the tongue plates 38, slots 39 
and latch 40. As the track increases in overall length, the support bar 32 
is raised to higher locations 34b on the frame 8. 
As shown in FIG. 1, when the final track segment 17d is in place, the 
target location, inlet 6, is between the wheels 41 and the frame 8. A 
sufficient portion of the segment 17d remains in the steam generator to 
permit attachment of the trolley 11 and operation of the winch 14. The 
trolley wheels 16 are passed into channels of the frame 17, as shown in 
FIG. 2, and the trolley is attached to the winch control line 13 is 
attached to, and wound onto winch drum 44, FIG. 7. This operation is aided 
by the manual engagement of a latch pin (not shown) which prevents 
movement of the trolley with respect to track 17. Preferably, a load tray 
36 is attached to bar 37 on the frame 8, for supporting the load, or 
nozzle plug 12. 
The operator then pays out control line 13 until support lines 21, FIG. 2, 
can be manually attached to plug 12 by snap hooks 22. Plug 12 is then 
winched up until line stops 25 contact the trolley frame 15, preventing 
further motion. The trolley, while still under the control of the 
operator, is then disengaged from track 17 by removal of the latch pin, 
(not shown). The operator then pays out the control line 13 until the 
trolley 11 contacts the stop means 26 (see FIG. 3), and the load is 
lowered into the inlet 6. The stop means 26 are attached to the track 17 
before deployment of the system, based on knowledge of the distances and 
elevations represented in FIG. 1. 
After the plug is in place, the operator exits from the steam generator 3, 
and returns after the maintenance work in the primary piping is completed. 
The nozzle plug and tooling system are then removed in reverse order.