Set-up method for steam generator tube installation apparatus

Method and apparatus for expeditious installation of bottom-supporting and side-anchoring blocks for a tube and tube sheet bottom repair apparatus in the interior of the channel head of a steam generator at one side of the divider plate in a nuclear power plant, involving use of special tools and fixtures for location and welding of such blocks in position by use of information derived from measurement of the extent and direction of tilt of the tube sheet bottom from a purely horizontal attitude.

CROSS-REFERENCE TO RELATED APPLICATIONS 
The invention described herein is related to commonly assigned U.S. Patent 
application Ser. No. 888,701 filed Mar. 21, 1978 on Apparatus For Remotely 
Repairing Tubes In A Steam Generator by L. R. Golick; commonly assigned 
copending patent application Ser. No. 952,431 on A Method And Apparatus 
For Servicing A Steam Generator by Cooper and Castner, filed concurrently 
herewith; and commonly assigned copending U.S. Patent application Ser. No. 
952,430 on Heat Exchanger Tube And Tubesheet Location Sensing Device And 
Method by Gerkey, Castner and Stiller, also filed concurrently herewith. 
BACKGROUND OF THE INVENTION 
This invention relates to nuclear steam generators and more particularly to 
a method and apparatus for set-up of a particular piece of equipment as 
disclosed in copending commonly assigned U.S. Patent application Ser. No. 
888,701 filed Mar. 21, 1978 of L. R. Gollick directed to apparatus for 
remotely repairing tubes and/or the tube sheet in such a nuclear steam 
generator. 
In pressurized water nuclear reactors primary fluid or coolant is pumped 
through a reactor and a steam generator, radioactive contaminants in the 
primary fluid are deposited on the tubes and in the channel head of the 
steam generator so that repair crews are subjected to significant 
radioactivity when working within the channel head. Therefore, in behalf 
of minimizing the exposure of personnel to radiation, apparatus and 
equipment of the type disclosed in the aforementioned copending patent 
application has been devised for inspection and repair of the tubes and 
the tube sheet within the steam generator under remote control, and in a 
manner as set forth in a copending patent application Ser. No. 952,431. It 
becomes important, in view of such minimal radiation exposure 
desirability, to provide for set-up of such equipment in minimal time, and 
to this the method and apparatus of the present invention is directed. 
SUMMARY OF THE INVENTION 
The method and apparatus of the present invention provides for rapid 
installation of a rotary support block member in the bottom spherical wall 
adjacent to the divider plate at the interior of the channel head of a 
nuclear steam generator undergoing tube repair. Which rotary bottom 
support member is intended for the lower-most end of a vertical column 
embodied in the tube repair apparatus of the aforementioned patent 
application Ser. No. 888,701. The present invention also involves 
installation of an anchor or pillow block member on the divider plate 
within the channel head adapted to accommodate attachment of a rotary 
column guide bracket at a selected vertical sight above the bottom support 
member for the column of the tube repair apparatus. On behalf of assuring 
trouble-free performance of the tube repair apparatus it becomes important 
that the bottom support bearing block member on the bottom wall of the 
channel head and the anchor block member on the divider plate be 
accurately positioned to provide for alignment of the column of the tube 
repair apparatus in an attitude of perpendicularity with respect to the 
tube-sheet in which the tubes undergoing repair are affiliated. To 
accomplish this in minimal time the apparatus in the method of the present 
invention determines and indicates the extent that the undersurface of the 
tube sheet is tilted from the horizontal by use of a special instrument 
introduced to the underside of the tube sheet and which includes a pair of 
commercially available inclinometers that give degree of tilt information 
in two mutually perpendicular directions readable via pick-off wires and a 
display at the exterior of the channel head. 
Using a plumb-bob fixture that is adapted to be accurately positioned with 
respect to a specific hole in the tube sheet, a center punch mark is made 
on the bottom spherical wall of the channel head directly beneath the 
chosen hole sight. 
By use of a center layouts template placed over the plumb-bob point on the 
bottom wall of the channel head locating marks for a positioning jig can 
be made on such bottom wall. 
A positioning jig for the location of the bottom column bearing block is 
then placed on the bottom wall of the channel head in accord with such 
markings and tack-welded in place; the bottom column-bearing 
rotary-support block is then placed in the center of the positioning jig 
and centered by use of adjusting screws affiliated with such jig. 
The bottom end of a vertical aligning post is then introduced into the 
bottom bearing block and locating pins at the top of the post are 
introduced into preselected holes in the bottom tube sheet by use of a 
hydraulic hand pump affiliated with such post to locate the upper end of 
the post in a selected site in the bottom of the tube sheet. 
By use of a pair of inclinometers affiliated with the locating post and the 
adjusting screws on the positioning jig the bottom of the post can be 
moved in selected directions until accord is reached between the output of 
the aligning post inclinometers and the previous inclinometer output of 
the tilt determining instrument. 
By application of additional pressure through use of the previously 
mentioned hydraulic hand pump, the bottom of the post can be made to 
introduce sufficient force to hold the bottom bearing block in place while 
it is then being welded to the bottom wall of the channel head. 
Monitoring of the readings of the inclinometers on the post while 
performing such welding, together with utilizing a sequence welding 
technique, assures that the desired alignment of the post will not be 
disturbed during the welding of the bottom bearing block. 
By use of a spring bias fixture mounted at a selected vertical location on 
the aligning post, the anchor block is positioned on the divider plate and 
held by spring pressure in position while being welded to such plate. 
By use of a shim of selected size and proximity sensing heads disposed in a 
simulated rotary column guide bracket on the post, the gap between such 
simulated rotary column giode bracket and the anchor block welded to the 
divider plate can be determined with a high degree of accuracy. 
By use of the hydraulic cylinder at the top of the column the aligning pins 
can be withdrawn from the locating holes in the tube sheet, the simulated 
rotary guide bracket on the post can be disconnected from the anchor block 
on the channel head by the simple withdrawal of a pair of coupling pins, 
and the aligning post assembly removed from the channel head by way of the 
usual manhole affiliated with such head. 
The vertical column of the tube repairing apparatus can then be introduced 
through the manhole, its bottom end inserted into the bottom bearing block 
on the bottom of the channel head and the real rotary guide bracket for 
the column secured to the anchor block by reinsertion of the coupling pins 
and adjustment made for affecting precise alignment of such column 
perpendicularly with respect to the bottom of the tube sheet and along a 
selected rotary axis by introduction of a proper size shim between the 
anchor block and the guide bracket chosen in accord with information 
derived by the previous measurement of the clearance between the simulated 
bracket member and such anchor block.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, the present invention is concerned with installation 
of a bottom rotary support block 1 to the spherical bottom wall 2 of a 
channel head 3 of a nuclear steam generator and the location and 
attachment of an anchor block 4 to the divider plate 5 in such channel 
head beneath the bottom of the tube sheet 6 in which the terminal open 
ends of the vertical tubes 7 of the steam generator terminate. The bottom 
support block 1 and the side anchor block are utilized for alignment and 
support of a tube and tube sheet repairing apparatus 9 as shown in FIG. 1 
and described in detail in aforementioned copending patent application 
Ser. No. 888,701 which apparatus utilizes a vertical column 10 supported 
at its lower end in the bottom bearing block 1 for rotation positioning by 
a motor 11 about a vertical axis 12 aligned with a particular tube hole in 
the tube sheet and extending perpendicularly from the bottom of such tube 
sheet by a rotary guide supbracket 13 removably attached to the anchor 
block 4. A horizontal boom 14 is pivotally carried at the top of the 
vertical column and supports a tool assembly 15 movable horizontally along 
the boom by way of a screw actuated carriage means 16. The boom is held in 
such horizontal position by a hydraulic cylinder assembly 17 operable to 
lower the boom to a retracted position adjacent to the column 10 and 
thereby realize a compacted state of the apparatus that affords its 
insertion and removal by way of the usual manway 18 affiliated with the 
channel head 3 of the steam generator. Removal of a pin 19 means 
affiliated with rotary guide bracket on the column provides for 
disconnection of the apparatus from the tube head. 
The present invention is concerned with installation of the bottom bearing 
block 1 for the vertical column 10 of the tube repairing apparatus 9 and 
the anchor or pillow block 4 at one side of such column at a selected 
heighth thereon. It will be appreciated that, at such initial preparatory 
stage, the tube repair apparatus 9 depicted in FIG. 1 will be absent from 
the interior of the channel head as also will be the bottom support block 
1 and the pillow block 4. 
In accord with the present invention a worker or workers will enter the 
interior of the channel head 3 through the manway 18 and will use the tilt 
sensing instrument of FIGS. 2 and 3 to determine the degree of tilt of the 
bottom of the tube sheet 6 relative to the horizontal. Referring to FIGS. 
2 and 3, the instrument is specifically adapted to this purpose and 
includes an inclinometer sensor means 20 adapted to feed signals to a 
digital readout located externally of the channel head by way of lead 
wires (not shown). The inclinometer sensor means 20 is capable of 
detecting the degree of tilt in mutually perpendicular directions in the 
horizontal plane and the instrument includes two pairs of horizontally 
spaced apart aligning pins 21 adapted for insertion in four tube holes 
opening downwardly from the bottom of the tube sheet. By proper selections 
of particular holes, the orientation of the instrument will be such that 
the tilt information derived from the inclinometer sensor means will be 
made with reference to a line extending centrally from and perpendicular 
to the divider plate 5. The instrument includes a horizontal arm 22 that 
carries such locating pins at its opposite ends as well as such 
inclinometer means at its midlength. The instrument also includes a pair 
of handles 23 to facilitate its manipulation during use and two pairs of 
pin-actuated interlock switch assemblies 24 at its opposite ends that 
operate to indicate when the arm of the instrument is parallel to the 
bottom surface of the tube sheet in the selected direction of extension of 
such arm. Each of the interlock switch assemblies includes an actuating 
pin 25 that has an end projecting upwardly from the top surface of the 
horizontal arm of the instrument and which is displaceable inwardly 
against the bias of a helical compression spring 26 by engagement with the 
undersurface of the tube sheet to actuate a microswitch 27 at the time a 
limit position defined by an annular shoulder 23 on the pin reaches its 
travel limit position. When the instrument is free of the tube sheet the 
extent of projection of the actuating pin is determined by a second 
annular stop surface 29 affiliated with the opposite end of such pin. The 
second annular stop surface may be formed in a removable part of the pin 
to accommodate assembly and disassembly. 
The readings from the inclinometer tilt measuring instrument with respect 
to tilt of the tube sheet 6 in the x and y direction relative to the 
perpendicular line (not shown) extending from the divider plate 5 is noted 
and recorded for subsequent use. 
By use of a plumb-bob 30, FIG. 4, aligned with a particular tube hole or 
location on the tube sheet, a punch mark is made on the bottom wall 2, 
FIG. 7, of the channel head. Plumb-bob 30 forms part of an assembly 
including a horizontal arm 31 and a locating pin assembly 32 extending 
above the upper surface of the arm and adapted for insertion in a 
particular tube hole in the tube sheet. Such assembly includes a rubber 
portion 33 squeezed between rigid members 34 and 35 in an axialwise 
direction by operation of a rocking level 36 via a tension member 37 to 
cause such rubber portion to expand radially into friction locking 
squeezed engagement with the inner wall of the respective opening. The 
lever has a camlike portion 38 affiliated with it to enable such squeezing 
action on the rubber member to be established or disestablished according 
to direction of turning of the leaver. 
Following such punch marking of the vertical alignment from the tube sheet 
on the spherical bottom wall 2 of the channel head a template 40 such is 
depicted in FIG. 5 having a center hold 41 is brought into registry with 
the punch mark and location markings are made on the wall by use of 
suitable location-marking openings 42 in the template. 
A rectangular, open frame positioning jig 44, FIGS. 6 and 7, is centered 
and located on the markings on the channel head wall 2 and tackwelded in 
place. The jig has two pairs of spaced apart screw-threaded lugs 45 
extending from its upper surface which are aligned along two mutually 
perpendicular directions, x and y. One of which is perpendicular to the 
divider plate surface and the other of which is parallel to such surface; 
it being appreciated that the desirable alignment is arrived initially by 
proper orientation of the template that was used to obtain the markings 
from which such positioning jig was located. 
A bottom bearing block 1 is then inserted into the jig 44 and centered 
therein on the wall 2 by adjusting screws 46. 
The lower end of a vertically extending aligning post 50, FIG. 7, is then 
inserted into the bottom 1 bearing block and a locating pin means 51 
affiliated with a locating assembly 52 at the top end of the aligning post 
is introduced into a selected tube hole in the tube sheet by operation of 
a hydraulic cylinder 53 affiliated with such locating assembly. A guide 
pin means 54 is affiliated with such locating assembly that operates to 
assure that the selected rotary aligned position of the locating pin means 
with respect to the tube sheet 6 and to the divider plate 5 will apply 
also to the aligning post assembly generally, so that an inclinometer 
means 55 mounted near the top of such aligning post will be properly 
aligned with respect to the divider plate 5 to give x and y tilting 
information relative to a line extending perpendicular to such divider 
plate. While monitoring the output readings of the inclinometers on the 
aligning post, the bottom thereof is moved in unison with the bearing 
block 1 by selective turning manipulation of the adjusting screws 46 
affiliated with the positioning jig until the inclinometer readings 
coincide with the previous readings obtained from the inclinometer means 
of the tilt measuring instrument; it being appreciated that the 
inclinometer means affiliated with the aligning post is so arranged as to 
be responsive to tilting of the column in a generally-horizontal plane 
perpendicular to the central vertical axis of such post. 
While applying additional pressure to the hydraulic cylinder 53 at the top 
of the column such as by the use of the hand pump (not shown) the bottom 
of the aligning post is made to hold the bottom bearing block 1 tightly in 
place on the bottom wall of the channel head. The adjusting screws 46 are 
then backed off and the positioning jig freed from its tackwelding 
attachment to the channel head. The positioning jig is then raised free of 
the bottom block by upward movement along the aligning post and storage 
attachment thereto by such as taping. 
While being so held against the bottom wall of the channel head the bearing 
block 1 is secured to the bottom wall by welding at the edges of the block 
in a manner which prevents shifting in the position of such block relative 
to the channel head. During such welding the output from the inclinometer 
means 55 at the top of the post can be monitored to detect any tendency 
for such shifting. 
Having thus installed the bottom bearing block 1 onto the bottom wall of 
the channel head chamber the rectangular anchor or pillow block 4, FIGS. 7 
and 8 is placed into position on the divider plate 5 and held in selected 
desired position by action of helical compression springs 58 affiliated 
with a simulated rotary guide bracket assembly 59 clamped to the aligning 
post by a pair of quarter-turn screws 60 and located at the desired 
vertical height on such aligning post by a pair of alignment tabs 61 
removably secured to such guide bracket in a selected rotary position on 
the post by screws 62. The tabs are slideable on the upper surface of a 
locating collar 63 on the rotary guide bracket which has a sliding fit 
with the outer periphery of the aligning post to provide frdeedom for 
sidewise position-adjusting movement of the anchor or pillow block 4 while 
abutting the divider plate. The extent of such adjusting movement is 
limited and once the proper position is obtained the rotary guide bracket 
can be clamped in place by tightening the mounting screws 62. A master 
dowell pin 65 cooperating between the anchor block and the guide bracket 
maintains centering relationship between these two members. While thus 
being held in place by the action of the helical compression springs 58 of 
the guide bracket, the anchor or pillow block 4 is welded to the wall of 
the divider plate 5. 
Referring to FIGS. 7, 8, and 9, the horizontal gap 68 between the anchor or 
pillow block 4 attached to the divider plate and the adjacent end of the 
simulated rotary guide bracket 59 is measured by a pair of proximity 
sensors 69 in the end face of such bracket, a suitable sensor being such 
as the Kaman sensor number 2UB bonded in place in a cavity in the end face 
of such guide bracket. To suit the operating ramge of the sensors, a shim 
means 70 of known thickness may be introduced into the gap in a region of 
the sensors and held in place against the gap-defining face of the pillow 
block 4 by a leaf spring clip 71 attached to the shim and abutting the 
corresponding face of the forward end of the guide bracket. The gap width 
is then arrived at by adding the thickness of the shim 70 to the reading 
from the sensors 69. This information is subsequently utilized to 
determine the thickness of a shim means (not shown) to be introduced 
between such pillow block and the rotary guide bracket 13 affiliated with 
the vertical column 10 of the tube repair apparatus with which such pillow 
block is intended to be affiliated. It being appreciated that the 
simulated rotary guide bracket 59 attached to the aligning post 50 is 
similar in critical dimensions to the corresponding rotary guide bracket 
13 affiliated with the vertical post 10 of the tube repair apparatus so 
that the gap measuring can be translated directly into thickness of the 
mounting shim for such apparatus. 
Finally, the aligning post 50 together with bracket 59 can be freed from 
the tube sheet by retraction of the locating pins by operation of the 
hydraulic cylinder 53 in the locating assembly atop such post and from the 
anchor or pillow block now welded to the divider plate by removal of 
coupling pins 72 that connect such block at opposite end to the guide 
bracket 59 through the medium of adjustable stop pin assemblies 73 
disposed in end slots 74 of such guide bracket. Such arrangement enabling 
initial installation of an anchor block 4 to the bracket 59 by connecting 
the adjustable stop pin assemblies 73 to the block by the coupling pins 72 
and then swinging the adjustable stop pin asemblies sideways into the end 
slots 74 of the bracket 59, with springs 58 in place. The installation of 
the anchor, or pillow block 4 together with the bottom bearing block 1 
within the channel head chamber is now complete, in accord with the 
objectives of the present invention, and the aligning post assembly can 
then be removed from such interior chamber by way of the manway 18. 
While the invention has been shown and disclosed herein in what is 
conceived to be a practical and preferred embodiment, it is recognized 
that departures may be made therefrom within the scope of the following 
claims.