Note: Descriptions are shown in the official language in which they were submitted.
S~
-1- 52,011
ANTI-VIBR~TION BARS FOR NUCLEAR STEAM GENERATORS
BACKGROUND OF THE INVENTION
.
Field Of The Invention
This invention relates to mechanisms for
supporting the tubes of a nuclear steam generator to prevent
vibration and, more particularly, to anti-vibration bars as
disposed between rows of the tubes and the method of install-
ing the anti-vibration bars to achieve reduced clearance with
and thus support of such tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims
particularly pointing out and distinctly claiming the sub-
ject matter of the invention, it is believed that the
invention will be better understood from the following
description taken in conjunction with -the accompanying
drawlngs, wherein:
Fiyures 1~ and lB are respect~vel~ a perspec-
tive view of a nuclear steam yenerator, wherein its U-
shaped tubes are supported by an upper tube supportassembly in accordance with the teachings of this invention,
and a cross-sectioned view particularly showing the anti-
vibration bars of this invention and the manner in which
they are assembled into the upper tube support assembly;
Figure 2 is a perspective view of a test rig
for receiving first and second rows of test tubes between
which are disposed an anti-vibration bar;
Figures 3 and 5 show plan views of the rows of
test tubes illustrating, respective~y, an anti-vibration
2~ bar before and after deformation, whereas Figures 4 and 6
are side views respectively of the arrangements of Figures
3 and 5 showing the anti-vibration bar in cross-section;
Figure 7 is a schematic diagram of the test
rig of Figure 2 as coupled to a controllable source of pres-
surized fluid;
Figures 8A and 8B show respectively an oval
shaped anti-vibration bar and such a bar in contact with a
U-shaped tube;
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Figures 9A and 9B show respectively a second
embodiment of this invention in the form of a hollow rectang-
ularly shaped anti-vibration bar and the manner in which it
contacts a U-shaped tube; and
Figures lOA and lOB show respectively a third
embodiment of -this invention in the form of a rectangularly
shaped anti-vibration bar with foldable side portions and the
manner in which such a vibration bar contacts a U-shaped tube.
Description Of The Prior Art
A nuclear steam generator 8 of the type found
in the prior art is shown in Figures lA and lB of the attached
drawings, as comprising a bundle 11 of a large number of vert-
oriented U-shaped tubes 13. The tubes 13 are disposed in a
lower, cylindrically shaped shell 9 of the steam generator8,
whose bottom end is associated with a channel head 17, typic-
ally of a hemi-spherical configuration as shown in Figure lA.
The channel head 17 is divided by a partition 18 into a first
half typically known as a hot le~ 20, and a second hal.e
typically known as a colrl ler~ 22. The hiyh-temperature coolank
water from the nuclear reactor is introduced into the steam
generator 8, through a primary coolant inlet 24 into the hot
leg 20. The high-temperature coolant passes from the hot leg
20 into the exposed openings of the plurality of U-shaped
tubes 13, passing there through to be introduced into the
cold leg 22 and, finally, exiting from the steam generator 8
through a primary coolant outlet 26.
That portion of the steam generator 8, primarily
including the tube bundle 11 and the channel head 22 is re-
ferred to as an evaporator section 10. As shown in Figure lA,
the steam generator 8 further includes a steam drum section 32
comprising an upper shell 30, which contains a moisture
separator 34. Feedwater enters the steam generator 8 through
inlet nozzle 28 disposed in the upper shell 30 to be distrib
~ted and mixed with the water removed by the moisture
separator 34. This feedwater travels down an annular channel
surrounding the tube bundle li and is introduced into the
bottom of the tube bundle 11. The mixture of feedwater and
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recirculating water boils as the high temperature coolant
is circulated through the U-shaped tubes 13 of the tube bundle
11. The steam so produced rises into the steam drum section
32. The moisture separator 34 removes the entrained water
from the steam kefore the steam exits from the steam generat-
or 8 through a steam outlet 36 to a turbine generator (not
shown).
As shown in Figure lA, the U-shaped tubes 13
are supported in the configuration of the tube bundle 11 by a
series of lower tube supports 12 and an upper tube support
plate 14. As shown in Figures lA and lB, the upper tube
support assembly 14 complises a plurality of retainer rings
16a, 16b and 16c. As best shown in Figure lA, each of the
retainer rings 16 is of generally oval configuration. The
major and minor diameters of the retainer rings 16a, b and c
are progressively smaller, noting that -the retainer 16c is
disposed at the upper-most portion of ~he tube bundle 11.
pluralit~ of 9et9 of anti-vlbratlon bars 15 .is disposed
between adjacent rows oE the U-shaped tubes 13. One such set
of anti-vibration bars 15 is shown in Figure lB, it being
understood that successive sets of similar anti-vibration
bars 15 are disposed behind and in front of the illustrated
set. Each of the anti-vibration bars 15a, 15b and lSc is of
a V~shaped configuration with the ends thereof extending to
the circumference of the tube bundle 11 and connected to a
corresponding one of the retainer rings 16. For example,
one end of the anti-vibration bar 15a is secured as by tack-
welding to the retainer ring 16a and, in similar fashion,
the other end of the anti-vibration bar 15a is secured to
the same retainer ri.ng 16a. Figure lB illustrates a cross-
sectioned view taken through the tube bundle 11 showing that
the anti-vibration bars 15a, 15b and 15c are disposed to
support the upper ends of the U-shaped tubes 13, noting the
arrangement of the U-shaped tubes 13a to 13n in a row.
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This invention relates to a novel configuration
and method of constructing such anti-vibration bars 15.
Anti-vibration bars 15 are installed in the U-bend region of
the tube bundle 11 to control tube vibration caused by the
steam/water mixture flowing by the U-shaped tubes 13. In the
absence of anti-vibration bars 15, the U-shaped tubes 13
would vibrate and, if not controlled, would leak resulting in
the loss of the primary coolant into the steam supplied to
the turbine generator.
Anti-vibration bars of the prior art are typic-
ally of uniform cross-section, e.g., square or cylinder. On
the other hand, the U-shaped tubes 13 are of substantially
uniform cylindrical cross-section with the result that there
is a gap/clearance between the anti-vibration ~ars 15 and
the U-shaped tubes 13. Gaps between the U-shaped tubes 13
and the anti-vibration bars 15 are not desirable for tube
performance or from a reliability point of view and are
difficult to make small. The U-shaped tubes 13 and the anti-
vibration bars 15 have dimensioned tolerances ~nd are assem-
bled such that close contact there between is difficu~t tomaintain. For example, normal tolerances occur in the ou-ter
diameters of the anti-vibration bars 15 and the U~shaped
tubes 13. The forming tof the U-shaped tubes 13 results in
oval cross-sections in their bend areas and their straight
portions may not be aligned precisely parrallel with each
other. Further, the openings within the tube support plate
14 may not be precisely spaced so that the spacing between
adjacent U-shaped tubes 13 in the region of their bends rnay
not be uniform.
SUMMARY OF THE INVENTIO~
It is thereEore an object of this invention to
provide new and improved anti-vibration bars that have
decreased clearance from the U-shaped tubes of a nuclear
steam generator, whereby the degree of tube support is
improved.
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It is a more specific object of this invention
to provide a new and improved method for installing anti-
vibration bars between rows of U-shaped tubes in a manner
that the contact surface of the anti-vibration bars is
conformed to the configuration of the U~shaped tubes.
In accordance with these and other objects of
this invention, this invention provides a new method of
forming and installing anti-vibration bars into a tube
bundle of a steam generator, the tube bundle comprised of
rows of tubes, each tube carrying a high temperature
coolant. Each of the anti-vibration bars has a tubular
configuration and is disposed between adjacent rows o:E the
tube bundle for stabilizing the tubes against vibration
caused by fluids flowing through the steam generator. The
method of this invention comprises the steps of inserting
at least one anti-vibration bar between adjacen~. rows of
the tube bundle and applying a pressurized Eluid -to the
hollow anti-vibration bar, thus expanding the b~r
circum~erence to contact the tubos ~ ~he adjacent: rows
and to provide a series of contacts with minimum clearances.
Typically, the pressure of the fluid is applied at a
pressure sufficient such that the configuration of the steam
generator tubes is not deformed. In one illustrative
embodiment, the maximum pressure level has been found to be
5000 PSI. The resultant anti-vibration bar is a hollow
member and has first and second series of contacts disposed
on opposing sides thereof and spaced a uniform distance from
each other corresponding to the spacing between adjacent
tubes of a row. The contact spacings are minimized to
provide effective support the tubes ayainst vibration.
Preferably, the anti-vibration bars are of an oval conEigur-
ation with the first and second series of contacts aligned
with the minor axis of the oval configuration.
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DESCRIPTIO~ OF THE PREFERRED EMBODIMENT
Referring now to the drawings and, in particu-
lar, to Figure 2, there is shown a test rig 40 for receiving
and imparting a series of indentations 50 to an anti-
vibration bar 15. The test rig 40 comprises an upper plate
42a, front and back plates 42d and 42b and a lower plate 42c,
rigidly held together by bolts as shown. The upper plate
42b has first and second rows of openings 46 and 48, for
respectively receiving first and second rows of test tubes
13l' and 13l. As illustrated in Figures 2 and 3, ~he anti-
vibration bar 15 is disposed between the first and second
rows Oe test tubes 13' and 13l'. Each o:E the Eirst set of
openings 48 has a conEigurakion and dimension substantially
slmilar -to tho~e o the test tubes 13 Eor riyidly clisposlny
khe test tube3 13, wherea~ each o the second set oE open-
ings 46 is of substantially oval configuration to permit
the second set of test tukes 13ll to be directed toward the
first rows of test tube 13'
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whereby the spacings between corresponding pairs of the
test tubes 13' and 13" may be variably set, thus duplicat-
ing the inconsistent spacings be~ween U-shaped tubes 13 of
a typical tube bundle 11. As illustrated in Figure 2, a
set of micrometer heads 44a, 44b and 44c may be manually
rotated to variably set the spacings between opposing test
tubes 13' and 13".
As shown in Figures 3 and 4, the oval-shaped,
tubular anti-vibration bars 15 have initially a uniform
1~ minor diameter before they are compres ed as will be
explained. The anti-vibration bars lS of this invention
are tubular in character to permit their deformation by
the application of fluidized pres~ure, whereby a minimun
gap contact lq achieved with the U-shaped tube3 13, thus
imp~ovlnq the vibra~ion support provided to the~e tubo~
13. In particular a~ shown in Figure 5, a series of
indentations 50a, 50b and 50c, etc., is provided in the
anti-vibration bar lS by applying a pressurized fluid
thereto. The diameter B along the minor axi 5 of the
oval-shaped anti-vibration bar 15 is shown in Figure 4
before the application of pressure. As illustrated in
Figures 5 and 6, opposing indentations 50a, 50b, 50c,
etc., are imparted to the anti-vibration bar 15 and the
minor diameter A of the anti-vibration bar 15 there be-
tween is slightly increased by the application of pres-
surized fluid with respect to the minor diameter B. The
application of the fluidized pressure increases signii-
cantly the minor diameter C of the deformed anti-vibration
bar lS at a point approximately midway between adjacent
indentations 50. It is realized that deformation may
incxease slightly the minor diameter A from the original
minor diameter B. As particularly illustrated in Figure
5, the surfaces of the indentations 50 tend to conform to
the configuration of the opposing test tubes 13' and 13~,
whereby the size of the gap~ between the anti-vibration
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bars 15 and the tubes is minimized. The minimized gap
between the tubes and anti-vibration bars 15 improves the
support provided by the anti-vibration bars 15 to the test
tubes 13, thereby reducing the vibration and the risk of
primary coolant leakage. Maintaining the gap slze at 3
mil or less is believed to result in the desired tube sup-
port and vibration reductionO
The mechanical deformation of anti-vibration
bars 15 is carried out after the assembly and installation
of the U-shaped tubes 13 as the tube bundle 11. In a pre-
ferred embodiment of this invention, method and apparatus
are provided for a hydraulically deforming anti-vibration
bars 15 as i]lustrated in Figure 7~ Figure 7 illustrates
an anti-vibration bar lS dispose between first and 3econd
~OW9 of the test tubes 13' and 13" as supported by the
te~t rig 40 a~ explalned above. A pump 72 ~upplies a reg-
ulated, pressurized fluld, such as water, to the
anti-vibration bar 15, whereby the anti-vibration bar 15
is expanded and a series of indentations SOa, 50b, 50c,
etc., as shown in Figure 5, is imparted to the
anti-vibration bar 15. It is understood that in the pre-
ferred method of compressing and installing the
anti-vibration bars 15, that the V-shaped tubes 13 are
first assembled into the tube bundle 11 as illustrated in
Figures lA and ~, and thereafter the pump 72 is coupled
sequentially or in other de~irable order to each of the
anti-vibration bars 15 to impart the desired deformations.
As shown in Figure 7, the pump 72 is coupled by
a conduit 64 and a fluid coupling 64b to the one end of
the anti-vibration bar 15. The opposite end of the
anti-vibration bar lS is attached to a fluid coupling 64a,
which serves to prevent the leakage of ~he pressurized
fluid, thus serving to permit the increase of pressure
within the anti-vibration bar 15. The pump 72, which may
in one illustrative embodiment comprise a model
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S-440-60-SS as manufactured by SPRAGUE, pumps the fluid
via the conduit 66 and coupling 64b to the anti-vibration
bar 15. A pressure gauge 68 is coupled in circuit between
the pump 72 and the anti-vibratio~ bar 15, whereby a mea-
~urement of fluid pressure is obtained~ Further, a pres-
sure recorder 70 is connected to the pressure gauge 68,
whereby a record of the fluid pressure may be kept,
primarily, to ascertain the maximum fluid pressure. The
pressure gauge 68 and the pressure recorder 70 may illus-
tratively take the form of those models D-HS and
LS-600-650 as manufactured by BLH and LINSEIS, respec-
tively.
In an illustrative embodiment of this invention,
an oval-shaped anti-vibration bar 15', as illustrated in
Figures 3A and 8B, having a major diameter of 0.40 inches
and a minor diameter o~ 0.30 inches wa~ disposed between
first and second rows 13' and 13" as positioned by the
test rig 40. Fluid pressure was established within the
anti-vibration bar 15 and gradually increased by the pump
72 to a maximum pressure. Illustratively, the oval-shaped
anti-vibration bar 15' may have a wall thickness of 0.02
inches and be made of that stainless steel known as
type 304.
As illustrated in Figures 2 and 5, the pairs of
test tubes 13' and 13" are deposed at six locations 1! 2,
3, 4, S, and 6, each pair spaced 1 inch from an adjacent
pair. In order to demonstrate the feasibility of this
method of deformation, the spacin~s of the tube paixs 1 to
6 were set respectively to be .372, .340, .372, .300~ .372
and .300, as would simulate the variations and spacings
found within the tubes 13 of a typical tube bundle 11.
The pressure was incrementally raised by the pump 72 in
steps of 500 PSI until a maximum of 5000 PSI was reached,
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before returning the pressure to 0. The following series
of relatively uniformed diameters A and C rPsulted:
Pressure, Di~eter ~inch) at Loc2tion
~S~ 1 1-2 2 2-3 3 3-4 4 4-5 ~ 5~6 6
0 .292 .295 .Z95.296 .298 .296 .297 .297 .29~ .257 .25~
500 - -.~18 .317 .~20.314 .315 .316 .300 .31~: .311 .314 .~00
1000 .331 .344 .340. ~4~ .3Z9 .341 .300 .33'~ .320 .335 .300
15C0 .372 .349 .3q~.35~ .372 .352 .300 .351 .372 .345 .300
2000 .372 .369 .340.365 .37~ .364 .300 ~36" .37~ .36~ .3G0
1 0 2509 .372 .381 .340.379 .372 .379 .~00 .376 .37~ .374 .30~
3000 .372 .3es .3~0.35~ .372 .3~.3Uû .3~4 .372 .3~1 .300
3500 .372 ;3sa .~40.39s .372 .396 .300 .3~ .372 .39a .30tJ
4000 .372 .4~0 .340.401 .372 .402 .30~ .359 .372 .404 .30~
45G0 .372 .409 .340.409 .372 .409 .300 .40i .372 .404 .300
50G~ .372 .410 .340.411 .372 .412 .30~ .409 .372 .4~9 .300
O .372 .39. .3~.389 .37~ .395 .300 .364 .372 .3a7 .300'
Further, tests have ~hown that when the pressure
is ral~ed greater than a predetermined maximum, e.g.,
5000, ~or the particular ovAl-shaped anti-vibration bar
15', that the anti-vibration bar 15' may deform the cylln-
drical configuration of the tubes 13. Such deformation of
the U-shaped tubes 13 may threaten their structural integ-
rity, which must be avoided by limiting the predetermined
maximum in view of the particular construction, e.g.,
material and dimensions, of the anti-vibration bar 15.
Referring now to 9A and 9B, there is shown a
further embodiment of this invention, in which an
anti-vibration bar 15" is configured as a rectangle having
relative thick top and bottom side~ 15a and 15c as
3~ compared to side walls 15b and 15d. Dimensions B ancl C as
shown in Figure 9A are respectively 0.30 and 0.50 inches.
Figure 93 illustrates the anti-vibration bar 15" after it
was pneumatically expanded, whereby the side 15d is
curved.
Referring now to Fiyures lOA and lOB, a third
embodiment is illustrated, wherein anti-vibration bar
15'" has side walls 15f and 15h interconnected by
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~lexible side walls 15e and 15g. The dim~nsions B and C
are similar to those of the anti-vibration bar 15" as
shown in Figure 9A. Of the three illustrative
embodiments, the oval-shaped anti-vibration bar 15' is the
preferred embodiment in that it is relatively easy and
inexpensive to manufacture.
In considering thi~ invention, it should be
remembered that the provided disclosure is illustrative
- only and the scope of this invention should be determinPd
by the appended claims.
