Note: Descriptions are shown in the official language in which they were submitted.
48,345
~PPARATUS F~R STEAM GENE ~ TOR
; TUBE ~U~PP~R SPACER AND SUPPOR~' BLOCK ~EMO~AL
U.S~ Patent 4~192,053 issued March 11, 1980
~: to R. A. Blanco and A, A. Massaro on a System Qnd Method
For Retubing A Steam Generator.
~ACK
.
Thls lnve~tion relates to a method and ~pparatu~
~or steam ge~erator ~ube wrapper spacer and ~upport block
remo~al, and more particularly to such method and appara
: ~u~ used during retubing o~ a steam generator in a nuclear
power plant.
~: Nuclear reactor power plants utilize a steam
genera~or having a tube bundle to transfer heat from a
primary side reactor_h~ated li~uid to water on a secondary
side to ~orm ste~m ~or drlving a turbine. Condenser leaks
. ln power pl~nt ha~e caused circulating water, whi~h is
often brackish, to mix with the seco~dary-side water i~
the steam generator, resulting in the buildup o~ undesir-
able chem1cals ~n the tube bundle. Water trea-tmen~ and
blowdo~ ha~e not completely protected the steam generator
tubes ~rom corroæion and leak~. As the ~umber o~ tubes
subject to ~uch leaks lncreases, the desirability o~
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replacement or repair on ~he steam generator increases.
Since removal of a steam generator in its entirety from a
nuclear power plant requires removal of a large portion of
a reinforced concrete containment vessel, such replacement
of a generator in its entirety becomes time-consuming,
expensive, and therefore undesirable.
SUMMARY OF THE INVENTION
The present invention is related in general to
the replacement of the tube bundle in a steam genera~or in
a nuclear power plant and more particularly to a method
and apparatus for rapidly cutting through the spacers and
the support blocks in the annulus be-tween the outer shell
of the generator and the cylindrical wrapper that encir-
cles the tube bundle in such a generator. The pr~sent
invention contemplates the use of a cutting torch in such
annulus supported by a multi-section swpport column made
up of a number of interlocked separable alwminum channel
sections supported by way of an adjustable hori~ontal
support arm assembly by a motorized carriage movable
vertical]y along an upright rack-and-guide member clamped
to and supported by the wpper edge of -the wrapper. The
support column, by virture of being formed from channel
sections of U-shape in cross section, forms an elongated
vertical cavity on one side which accommodates di~position
o the hoses for the cutting torch. By manipulation of an
upper column clamp on the support arm assembly and a lower
column clamp affixed to the top of the wrapper the motor~
ized carriage can be made to raise and lower the column
for addition and swbtrac tion of channel sections as well
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as vertical traverse of the cutting torch past the work-
pieces.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a ver~ical perspective view of the
tube-bundle-containing portion of a nuclear power plant
steam generator shown partially in section after removal
of the top portion thereof and affiliation with the cut-
ting apparatus of the present invention;
Fig. 2 is a side elevation outline view of the
torch support column embodied in the apparatus of the
present invention;
Fig. 3 is a rear elevation outIine view of the
column of Fig. 2 showing details of~channel junction
regions thereof;
Fig. 4 is a side elevation section view taken
along the line IV-IV in Fig. 3;
Fig. 5 is a transverse section view of the
column of Figs. 2, 3 and 4 taken along the line of V-~ in
Fig, 3;
20Fig. 6 is a fragmental elevation view of the
upper edge of the wrapper of a nuclear steam generator on
which the upper end of the cutting apparatus of the pre-
sent invention is shown installed;
Fig. 7 is a fragmental plan view showing the
cutting apparatus of the present invention installed on
the upper eclge of the wrapper of the steam generator of a
nuclear power pl.ant;
Fig. 8 is a bottom view showing a cutting torch
- embodied in the apparatus in the present invention in
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working position in affil.iation with a mounting block
member disposed between the wrapper and the shell of a
nuclear steam generator;
Fig. 9 is an elevation view, p~rtly in outline
and partly in section of the cutting torch region of the
apparatus of the present invention shown in association
with mounting block members disposed in the annulus be-
tween the wrapper and the shell of a nuclear steam gene-
rator;
lo Fig. 10 is a front elevation view showing in
outline a spring-biased spacer member affiliated with a
portion of the torch supporting column in the apparatus of
the present invention;
Fig. 11 is a view taken along the line XI-XI in
Fig. 10;
;~ Fig. 12 is a section view taken along the line
XII-XII in Fig. 10;
Fig. 13 is a plan view of a toggle clamp assem-
bly utilized in the apparatus of the present invention for
holding the torch supporting column of the present i.nven-
` tion supported;
Fig. 14 is a developmental view of a wrapper of
a nuclear steam generator showing typical locations and
sizes and types of spacers and support blocks associated
with such wrapper as ins-tallecl inside the shell of such
generator;
Figs. 15 and 16 are vertical elevation and
bottom views, respectively, of a dual torch assembly for
cutting channel-shaped spacer members disposed between the
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wrapper and shell of a nuclear steam generator; and
Fig. 17 is an oiltline elevation view of a pre
ferred construction for interconnecting ends of the torch
support column of the present invention including an
improved pneumatically operated stabilizer assembly on the
lower torch-bearing end of the column.
DETAILED _ESCRIPTION OF THE INVENTION
Referring to Fig. 1 in the drawings, the steam
generator l with which the method and apparatus of the
present invention are intended to be employed typically
; includes a vertically oriented shell 3, the shell com-
prising a lower cylindrical portion 5 and an upper cylin~
drical portion 7, larger in diameter than the lower por-
tion 5, and a frusto-conical transition portion 9 joining
the lower and upper portions 5 and 7. A tubesheet ll is
disposed in the lower end of ~he lower portion 5 of the
shell 3 and has a plurality of holes for accommodating the
ends of U-shaped tubes 13 which extend upwardly from the
tubesheet ll and are closely packed to form the tube
bundle 23 disposed vertically within the lower portion 5
of the shell 3.
A hemispherically shaped channel head 15 is
fastened to the tubesheet 11 and has a divider plate 17
di.sposed therein. A primary fluid inlet nozzle 19 sup-
plies heated primary 1wid from a nuclear reactor core
(not shown) to one portion of the channel head 15 and a
discharge nozzle 21 provi.des for return of the primary
fluid to such reactor core.
A plurality of support plates 25 are disposed
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throughout the height of the tube bundle to support the
twbes 13 at various locations along their :Length to reduce
flow-induced vibrations. Anti-vibration bars 27 are also
disposed adjacent to bends in the tubes 13 to prevent
vibration in this portion of the tube bundle 23. A wrap-
per or sleeve 29 is disposed 'between the tube bundle 23
and the shell 3 so as to form an annulus or annular space
31 therebetween. As shown in Fig. l, the upper part of
: the~upper section 7 of the shell 3 has been removed to
gain access to the interior of the steam generator in
preparation for removal and replacement of the tube bundle
23 therein. Various components on the steam generator
usually disposed in the upper section.7 also have been
r'emoved from the generator as shown in Fig. 1 to~provide
access to the top of the wrapper 29 and to the tube bundle
23 encircled thereby.
Involved in removal of the tube bundle 23 ls the
removal also of the wrapper 29 which, in turn, involves
; the separation or substantial removal of a plurality of
20 channel-shaped spacer members 34, Figs. 1 and 14, and pads
or blocks 35 extending between the exterior of the wrapper
29 and the interior of the shell 3 in the annu'lar space
31; the channel spacers 34 serving to maintain evenly
distributed spacing around the periphery of the wrapper 29
and the pad or blocl~ assemblies 35 providing for support
of the wrapper 29 by the shell 3, T'he primary function of
the apparatus and method of the present invention is to
cut through and thereb~ effectively remove the channel
spacers 34 and the support pads or block assemblies 35 to
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free the wrapper 29 for removal.
Referring to Figs. 1, 8 and 9, the cutting
apparatus of the present invention includes a cutting
torch assembly 38 carried on the lower end of a multi-
section vertical support column 39 extending downwardly in
the annular clearanceway 31 between the outside of the
~rapper 29 and the interior of the shell 3. Torch assem-
bly 38 includes a nozzle 40 in receipt of operating gases
such as oxygen and acetylene by way of downwardly extend-
ing supply tubes 41 to produce a cutting flame directedsidewardly toward the workpiece parts to be severed, such
as the pads or block members 35 in Figs. 8 and 9 and the
channel members 34, etc. in Figs. 1 and~ 14, ior example.
The torch assembly also i-ncludes a guard member 42 that
extends forwardly from one side of the nozzle 40 for
~ contact with workpiece members to maintain the nozzle at a
.~ proper distance away from such member. The member 42 is
curved to facilitate sliding over irregularities in the
workpiece parts such as exemplified in Fig. 9. Torch
assembly 38 can be supported through the medium of the
working gas supply tubes 41 and tube clamping means 44
affiliated with the column 39. The attitude of the torch
nozzle 40 is such that the cutting flame generated by such
; nozzle :is directed suhstantially parallel to and adjacent
~o the outer wall o: ~he wrapper 29 and tends to be kept
away from the inner wall of the shell 3 of the steam
generator.
The suppor-t col-umn 39 is made up of a number of
aluminum channel sections 46 that are open between pro-
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jecting webs on one side and closed on the other and which
sections provide at their interior a passageway for accom-
modating extension of the operating gas supply tubes 41
enroute to the cutting torch nozzle 40. In the lowermost
one of the support column sections 46 the tube gas supply
tubes 41 will be rigid, but above such section extensions
of such tubes 41 occur by way of flexible hoses 48, Figs.
6 and 15 3 for example. According tc a feature of the
present invention the column sections can be added one by
one to obtain the desired vertical location of the cutting
torch with respect ~o the workpiece parts to be severed
and this is enablecl by provision of coupling assemblies at
the adjacent ends of the column sections. Referring to
~ Figs. ~, 3 and 4, for example, these coupling assemblies
- include a plurality of pins that project inwardly at such
as the lower end of the column section for insertion into
openings 51 in an insertable tab portion 52 extending
upwardly from the upper end of an adjacent column section.
The pins 50 have neck-down or recluced diameter portions
that seat in the bottom of the holes 51 as urged thereto
by operation of a clamping meehanism 54 at the lower end
of a respective eolumn seetion and which ineludes a mov-
able locking finger member 55 that engages a fixed loeking
finger 56 at the upper end of the insertable tab member 52
attachecl to the upper end of the adjacent column seetion
46. The si.ze of the openings 51 relat:ive to the eonfigu-
ration o~ pins 50 is sueh that when loeked in place the
large portions of the pins 50 form annular shoulders that
malntain the reduced tab portion 52 seated against the
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inner widthwise face of the lower end of -the adjacent
col~mn section. By raising an operating tab 58 and turn-
ing a cam (not shown) by a shaft 59 the grip of the mov-
able finger 55 may be relaxed to enable the lower column
section 46 to slide under influence of gravity downwardly
relative to the upper column section until the pins 50 are
centered in the openings 51 to permit separation of the
~wo column sections. Handgrip rings 60 on the ends of
removable mounting pins 61 are provided at one side of the
column sections in appropriate locations to assist in
manipulation of the column sections during assembly and
disassembly. In Fig. 17 a preferred single-pin arrange-
ment is shown with toggle type clamping assemblies at
opposite side edges of the column sections to give less
obstruction to the interior of the channel sections for
accommodation of the operating gas supply tubing at the
interior of the channel then otherwise may be afforded by
the clamping assembly shown in Figs. 2 to 5.
To provide for manipulation of the cutting torch
vertically a pair of toggle clamp assemblies 65 and 66 are
provided. The column clamp assembly 65 is mounted direct-
ly on the upper end of the wrapper 29, while the column
clamp assembly 66 is carried at one end of the adjustable
horizontal support arm assembly affiliated with the verti-
cal].y movab:l.e motorized carriage 68. By use o the clamp
66 and opera~:ion of the motorized carriage 68 the column
39 can be raised and lowere~ in the annular space 31 to
bring the cutting torch assembly 38 into working positions
at different levels within such clearanceway, as well as
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to provide vertical scanning movement of the cutting torch
assembly pas t the workpiece members during its use at a
selected location; a television monitor camera (not shown)
being employed to assist ln orientation and use o the
assembly.
~ y manipulation of irst one and then the other
of the column clamp assemblies 65 and 66 column sections
46 can be added ~o and subtracted from the torch support
column 39. By use of a clual torch assembly such as shown
- 10 in Figs. 15 and 16 a torch assembly 38 is provided which
can be inserted between the webs of a channel-shaped
spacer member 34 to effect simultaneows throughcut of such
webs.
A suitable column clamp assembly of a toggle
variety is shown in Fig. 13 as including a manually oper-
l able handle 70 at the end of an arm 71 that is rockable
about a pivo-t pin 72 by way of a link 73 and a pin 74, to
cause a crank arm 7S to pivot about a fixed pin 76 by way
of a pin 77 on the arm 71 for actuation of an adjustable
movable clamping member 79 toward and away from one edge
of the column 39. A rigid backup clamping member 80 for
affiliation with the opposite edge of the column is inter-
connected with ~he pivot pin 72 and 76 by wayof rigid
structllral members 81 and 82 and securing bolts 83.
The upper column clamp assembl~ 66 is inter-
connected Wittl the motori.zed carriage 68 through the
medium of the adjustable arm assembl~ 85 constructed and
arranged to provide hor:izontaL adjwsting movement between
the carriage 68 and the clamp assembly 66. The motorized
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carriage 68, the arm assembly 85, and the upper column
clamp assembly 66 are supported and guided on a vertically
extending rack member 88 that acts to guide and support
the vertically movable carriage 68 and includes a rack
-~ portion 89, Fig. 6, with which such carriage means co-
operates to obtain vertical movement and positioning.
suitable carriage for this purpose may be such as that
provided by Union Carbide Welding Products and sold as an
All-Position Travel Carriage No. CM-77 that is self-
propelled, reversible, of variable speed, driven by way of
rack and pinion, etc.
The rack and guide member 88 on which the~motor-
ized carriage 68 travels is supported by a bracket assem-
bly 90 removably clamped by such as turn screws 91 to the
upper edge of the wrapper 29.
The cuttin~ torch apparatus of the present
invention may be moved to different circumferential sites
around the upper edge of the wrapper as required, by
relaxation of the clamp assemblies affiliated with the
column 88 and the support clamp 65.
To assist in proper radialwise location of the
column 39 when disposed within the annular clearanceway 31
between the wrapper 29 and the shell 3 spring-biased
expandable slide members 94 may be provlded on one or more
of the column sections 46 which s].idably cooperate with
the inner wall of the shell 3 and urge the column 39
toward the outer surface of the wrapper 29 such that its
otherwise open end between the webs thereof slidably
engage such outer wrapper surface. As is shown in Figs.
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10~ 11 and 12 the member 94 can be biased~by a helical
,
spring 95 suitably arranged in a ~socket portiQn of a
member 96 attached to the column section 4~.~ A pln 97 at
one end of the member 94 pivot~lly connects such one end
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to the member 96. Yieldable movement as ma~be required
; about the pin 97 can occur against opposition of~spring 95
at the opposlte end of such member 94. A stop finger 98
is formed in the adjacent portion of member 94 to prevent
escape of such member 94 under influence of bias spring
95.
Other arrangements may be equally effective or
preferred. For example, a pneumatically operable position
biasing assembly 100, Fig. 17, may be substituted :Eor the
spring-biased guide member 94. Assembly 100 may be oper-
ated selectively, for example, brought into play only
after the cutting torch has arrived at a selected vertical
work site and, by slidable engagement wlth the inner wall
of the shell 3 act to provide freedom for vertical move
ment of the column and torch assembly while opposing the
sidewise movement of such assembly during operation of the
cutting torch.
