U.S. patent number 3,927,497 [Application Number 05/414,747] was granted by the patent office on 1975-12-23 for supporting structure of pressure vessel.
This patent grant is currently assigned to Hitachi, Ltd.. Invention is credited to Kenji Matsuo, Takanao Wada, Toshiaki Yoshinaga.
United States Patent |
3,927,497 |
Yoshinaga , et al. |
December 23, 1975 |
Supporting structure of pressure vessel
Abstract
A supporting structure of a pressure vessel is disclosed in
which a footing formed integral with the lower edge of the side
wall of the pressure vessel is placed within an annular recess
formed in the concrete foundation and securely held in position by
anchor bolts and concerete blocks are disposed in the annular
recess inside the pressure vessel thereby holding firmly the
footing in position. Intermediate members are interposed between
the concrete foundation and the concrete blocks. When the side wall
and hence the footing of the pressure vessel is raised as the
internal pressure is increased, only the concrete blocks are raised
while the concrete foundation, that is the concrete floor remains
in the same position. Therefore no excessive forces are exerted to
the concrete foundation or floor so that cracking thereof may be
prevented. A portion of a liner support, which is embedded in the
concrete foundation within the pressure vessel for supporting
thereupon a lining plate, adjacent to the inner wall of the
pressure vessel is cut off and is not welded to the lining plate so
that the deformation of the lining plate is permitted when the
footing is raised. Thus the stress concentration at the joint
between the pressure vessel and the lining plate can be prevented,
whereby the lining plate may be prevented from being damaged.
Inventors: |
Yoshinaga; Toshiaki (Hitachi,
JA), Wada; Takanao (Hitachi, JA), Matsuo;
Kenji (Hitachi, JA) |
Assignee: |
Hitachi, Ltd.
(JA)
|
Family
ID: |
14623903 |
Appl.
No.: |
05/414,747 |
Filed: |
November 12, 1973 |
Foreign Application Priority Data
|
|
|
|
|
Nov 15, 1972 [JA] |
|
|
47-113898 |
|
Current U.S.
Class: |
52/169.1;
52/396.04; 52/247; 52/295 |
Current CPC
Class: |
E02D
27/38 (20130101) |
Current International
Class: |
E02D
27/38 (20060101); E02D 27/32 (20060101); EO2d
027/00 (); EO4b 001/92 () |
Field of
Search: |
;52/247,249,169,224,274,295,573 ;220/1B,18 ;61/46 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Ridgill, Jr.; James L.
Attorney, Agent or Firm: Craig & Antonelli
Claims
What is claimed is:
1. A supporting structure of a pressure vessel comprising:
footing means secured to a lower edge of a side wall of said
pressure vessel for installing the vessel on a concrete
foundation,
said footing means including a base plate fixed on the lower edge
of the side wall of said pressure vessel and a lining plate support
member joined to the inner surface of said side wall so as to
project therefrom,
liner support means installed in the concrete foundation inside the
side wall of said pressure vessel,
a lining plate mounted on the liner support means and fixed to the
lining plate support member at the edge thereof to form the bottom
surface of the pressure vessel,
said lining plate and said lining plate support member having
thereunder concrete for reinforcing them, and
a first means disposed adjacent to an inner edge of the base plate
at an end thereof and to an under surface of the lining plate at
the other opposite end thereof for permitting the concrete on the
base plate inside the side wall of the vessel to be moved with the
base plate, when an unusual pressure increase occurs in the
pressure vessel,
said liner support means having means for relieving the stress
produced in the lining plate when an unusual pressure increase
occurs in the pressure vessel said relieving means being disposed
at ends thereof facing said first means.
2. A supporting structure of a pressure vessel as set forth in
claim 1, further comprising an annular recess provided on the
concrete foundation which reinforces the lining plate for disposing
therein said footing means, said first means being disposed on the
inner side wall of said annular recess for separating the concrete
on the base plate inside the side wall of said pressure vessel from
the inner side wall of said annular recess, thereby permitting said
concrete to be moved when an unusual pressure increase occurs in
the pressure vessel.
3. A supporting structure of a pressure vessel as set forth in
claim 2, wherein said liner support means are provided with cut off
portions at ends thereof facing said first means.
4. A supporting structure of a pressure vessel as set forth in
claim 2 further comprising a pit portion formed between the outer
surface of the side wall of said pressure vessel and a concrete
structure provided on the concrete foundation outside of the side
wall of the pressure vessel in communication with the annular
recess outside of the pressure vessel, said pit portion containing
filler.
5. A supporting structure of a pressure vessel as set forth in
claim 4, wherein said liner support means are provided with cut off
portions at ends thereof facing said first means.
6. A supporting structure of a pressure vessel as set forth in
claim 4 further comprising concrete blocks fixed on the base plate
outside of the pressure vessel and a space formed between said
concrete blocks and the outer side wall of the annular recess, said
space containing the filler in the pit portion.
7. A supporting structure of a pressure vessel as set forth in
claim 6, wherein said liner support means are provided with cut off
portions at ends thereof facing said first means.
8. A supporting structure of a pressure vessel as set forth in
claim 1 further comprising a pit portion formed between the outer
surface of the side wall of said pressure vessel and a concrete
structure provided on the concrete foundation outside of the side
wall of the pressure vessel, said pit portion containing
filler.
9. A supporting structure of a pressure vessel as set forth in
claim 8 further comprising concrete blocks fixed on the base plate
outside of the pressure vessel and a space formed between the
concrete blocks and the inner side wall of the pit portion, said
space containing the filler in the pit portion.
10. A supporting structure of a pressure vessel as set forth in
claim 9, wherein said liner support means are provided with cut off
portions at ends thereof facing said first means.
11. A supporting structure of a pressure vessel as set forth in
claim 8, wherein said liner support means are provided with cut off
portions at ends thereof facing said first means.
12. A supporting structure of a pressure vessel as set forth in
claim 1 further comprising a pit portion formed between the outer
surface of the side wall of said pressure vessel and a concrete
structure provided on the concrete foundation outside of the side
wall of the pressure vessel, and a second means disposed on an
inner side surface of the pit portion and adjacent to an outer edge
of the base plate at an end thereof, for separating concrete placed
on the base plate outside of the pressure vessel from the inner
side surface of the pit portion, thereby permitting the concrete to
be moved when an unusual pressure increase occurs in the pressure
vessel.
13. A supporting structure of a pressure vessel as set forth in
claim 12, wherein said liner support means are provided with cut
off portions at ends thereof facing said first means.
14. A supporting structure of a pressure vessel as set forth in
claim 2 further comprising a second means disposed on an outer side
surface of the annular recess and adjacent to an outer edge of the
base plate at an end thereof for separating concrete placed on the
base plate outside of the pressure vessel from the outer side
surface of the annular recess, thereby permitting the concrete to
be moved when an unusual presure increase occurs in the pressure
vessel.
15. A supporting structure of a pressure vessel as set forth in
claim 14, wherein said liner support means are provided with cut
off portions at ends thereof facing said first means.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a supporting structure of a
pressure vessel and especially of a nuclear reactor containment
vessel.
In general a nuclear reactor such as a boiling-water type reactor
is placed within a reactor containment vessel in order to prevent
the release of significant radioactivity to the environment due to
the breakdown of the coolant circulation system. Therefore careful
consideration has been given in design of a nuclear reactor
containment vessel and its supporting structure in order to give
the special assurance to the safety of a reactor. However the
conventional supporting structure of a reactor containment vessel
is not satisfactory to give the maximum assurance to the safety of
a nuclear reactor as will be described hereinafter.
The footing of the conventional reactor containment vessel is
embedded into a concrete foundation and is securely held in
position by means of anchor bolts. Thereafter concrete is placed to
embed the anchor belts in the concrete foundation. The edge of a
lining plate which is placed upon the concrete floor within the
containment vessel is welded to the inner wall of the containment
vessel to provide a bottom thereof. Thus, the lining plate provides
the air- and water-tightness to prevent the release of
radioactivity to the environment. In order to prevent the
deformation of the lining plate due to its thermal expansion, it is
welded to upper ends of liner supports embedded in the concrete
floor within the containment vessel.
When the internal pressure is increased within the containment
vessel due to the breakdown of the coolant circulation system of a
nuclear reactor contained or in case of an earthquake, the side of
the containment vessel is subjected to the tensile forces which act
upwardly so that the anchor bolts are forced to elongate with the
result of the rise of the footing of the containment vessel. As a
result many cracks are propagated in the concrete floor with the
result of the dangerous decrease in load bearing capability
thereof. The concrete floor or foundation cannot contain the
internal pressure or cannot withstand the forces exerted thereto in
case of an earthquake once cracks are propagated in the concrete
floor or foundation. If the initial tightening loads of the anchor
bolts are increased, the elongation of the anchor bolts in case of
the increase in internal pressure or in case of an earthquake may
be prevented to some extent. However this method cannot overcome
the fundamental defects of the conventional supporting structure of
a reactor containment vessel because of the creep in the concrete
foundation, relaxation of the anchor bolts and the retightening of
the anchor bolts which must be carried out periodically.
Furthermore when the footing is raised or floated, the lining plate
welded to the inner wall of a containment vessel is subjected to
deformation. As a result considerably great stress concentrations
are induced in the joint between the lining plate and the inner
wall of the containment vessel, and in the worst case the lining
will be seriously damaged. The lining plate which is generally thin
and is provided for the purpose of preventing the release of
radioactivity to the environment must be free from the stress
concentration due to the deformation thereof. The internal pressure
acting upon the lining plate is received by the concrete foundation
below the lining plate.
SUMMARY OF THE INVENTION
In view of the above, one of the objects of the present invention
is to provide an improved supporting structure of a pressure vessel
capable of giving the maximum safety assurance.
Another object of the present invention is to provide an improved
supporting structure of a pressure vessel which may effectively
prevent the cracking of a concrete foundation even when a footing
of the pressure vessel is somewhat raised.
A further object of the present invention is to provide an improved
supporting structure of a pressure vessel capable of preventing the
deformation of a lining plate, which forms the bottom of the
pressure vessel, and the resulting stress concentration.
Briefly stated, the most important feature of the present invention
resides in the fact that the footing of a pressure vessel is placed
within a recess formed in a concrete foundation and is securely
held in position by means of anchor bolts embedded in the concrete
foundation and concrete blocks with intermediate members being
interposed between the concrete blocks and the concrete
foundation.
Another important feature of the present invention is provision of
the stress relieving means which are disposed adjacent to the joint
between the edge of the lining plate and the inner wall of the
pressure vessel.
The above and other objects, features and advantages of the present
invention will become more apparent from the following description
of preferred embodiments thereof taken in conjunction with the
accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a vertical sectional view of a first embodiment of the
present invention applied to a nuclear reactor containment
vessel;
FIG. 2 is a fragmentary sectional view, on enlarged scale,
illustrating a portion indicated by II in FIG. 1;
FIG. 3 is a cross sectional view taken along the line III--III of
FIG. 1;
FIG. 4 is a cross sectional view taken along the line IV--IV of
FIG. 3;
FIG. 5 is a cross sectional view taken along the line V--V of FIG.
4; and
FIGS. 6 and 7 are sectional views of second and third embodiments,
respectively, of the present invention.
Same reference numerals are used to designate similar parts
throughout the figures.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment, FIGS. 1 - 5
In the embodiments to be described hereinafter, the present
invention will be explained as being applied to a boiling-water
type nuclear reactor. FIG. 1 shows the supporting structure of a
reactor containment vessel generally indicated by numeral 1. The
containment vessel 1 has a footing generally indicated by 2 and
extended from the lower end of a side wall and anchored securely to
a concrete floor or foundation 4 by anchor bolts 5. Between the
containment vessel 1 and a concrete shield 7 and close to the
concrete floor or foundation 4 is formed a pit 9 into which is
filled sand. The pit 9 may be formed between the containment vessel
1 and the concrete foundation 4. Within the containment vessel 1
and upon the concrete floor or foundation 4 is laid a lining plate
11 whose edge is welded to the inner wall of the containment vessel
1. The lining plate 11 is also securely joined to liner supports 13
embedded into the concrete foundation 4. The liner supports are
securely fixed to the concrete foundation by anchor bolts 14. The
anchor bolts 5 and 14 are anchored to a concrete foundation mat 15
below the concrete floor or foundation 4.
FIG. 2 is a fragmentary sectional view, on enlarged scale, of the
containment vessel 1 shown in FIG. 1. The footing 2 of the
containment vessel 1 comprises a flange 22 joined to the inner wall
of the containment vessel 1, a base or foot plate 20, outer stays
24 joined by welding to the outer wall of the containment vessel 1
and its base plate 20 and inner stays 21 joined by welding to the
inner wall of the containment vessel 1, its flange 22 and base
plate 20. The flange 22 is connected by a suitable weld joint as at
23 to the inner wall of the containment vessel 1. The base plate 20
is fixed to the lower edge of the side wall of the containment
vessel 1 by welding. The footing 2 of the containment vessel 1 is
placed in an annular groove 26 in the concrete foundation or floor
4. Alternatively, the footing 2 may be divided into a plurality of
sections which may be placed in a plurality of arcuate recesses
formed in the concrete floor 4 along the same circle. The base
plate 20 is securely held in position by the anchor bolts 5
embedded in the foundation mat 15. After the nuts 6 of the anchor
bolts 5 are securely tightened, they are welded to the base plate
20 to prevent the loosening of the nuts 6. The upper surface of the
flange 22 substantially flushes with the surface of the concrete
floor 4 within the containment vessel 1 when the containment vessel
1 is installed. The anchor bolts 5 are interconnected with each
other by an anchor plate 28.
The liner suports 13 are embedded within the concrete floor 4 in
the form of a grill as best shown in FIG. 3, and are securely held
in position by the anchor bolts 14. Upon the lining supports 13 is
laid the lining plate 11 and welded thereto. The edge of the lining
plate 11 is welded to the flange 22 jointed to the inner wall of
the containment vessel 1. The welded portion between the lining
plate 11 and the flange 22 is designated by numeral 25. Because the
diameter of the bottom of the containment vessel 1 and hence the
diameter of the inner plate 11 is generally large, the lining plate
11 is divided into a plurality of sections in order to facilitate
the fabrication and transportation, and the component parts of the
lining plate 11 are assembled by welding on the field.
The joint between the liner supports 13 and the lining plate 11 is
best shown in FIG. 4. The sections of the lining plate 11 are
welded together along the liner support 13 at 33 and also welded
thereto. The upper portion of the web of the liner support 13
adjacent to the lining plate is cut off as indicated by 34 (See
FIG. 2) a predetermined length at the end of the liner support 13
adjacent to the inner wall of the containment vessel 1. The section
of the cut off portion 34 is shown in FIG. 5, in detail.
Referring back to FIG. 2, concrete blocks 36 are disposed between
the inner wall of the containment vessel 1 and the inner wall of
the annular recess 26 in the concrete floor 4 and between the
flange 22 and the base plate 20. An intermediate member 38 made of
paper, a thin wooden or metal plate is interposed between the
concrete block 36 and the inner wall of the annular recess 26.
The upper surface of the concrete block 36 is made into contact
with under surfaces of the flange 22 and the lining plate 11.
Alternatively, the length of the flange 22 may be so determined as
to cover the whole upper surface of the concrete block 36.
The portion of the annular recess 26 outside of the footing 2 of
the containment vessel 1 defines the bottom of the pit portion 9
into which is filled sand. Sand is also filled in the space above
the footing 2. Instead of sand, gravel may be used.
When the internal pressure inside the containment vessel 1
increases or in case of an earthquake, the supporting structure of
the containment vessel in accordance with the present invention can
absorb the external forces. The mode of absorbing the external
shocks produced when the internal pressure is increased due to the
breakdown of the coolant circulation system (not shown) will be
described hereinafter. The pressurized and high temperature steam
fills the containment vessel 1 so that the upward forces are
exerted to the footing 2. The anchor bolts 5 are exerted with the
tension so that they are elongated. Then the footing 2 is moved
upwardly as indicated by the two-dot lines in FIG. 2. That is, the
undersurface of the base plate 20 is raised to the level indicated
by the two-dot lines A so that the concrete blocks 36 are also
raised. Since the concrete blocks 36 are separated from the
concrete floor 4 by the intermediate members 38, no crack is
produced or propagated in the concrete floor 4 even when the
concrete blocks 36 are raised. Furthermore sand is filled in the
annular recess 26 outside of the containment vessel 1 so that even
when the footing 2 is raised no cracking is produced in the
concrete floor 4 outside of the containment vessel 1. Sand in the
pit portion 9 serves to prevent the stress concentrations upon the
wall of the containment vessel 1 close to the footing 2
thereof.
When the footing 2 is raised or floated, the lining plate 11 is
subjected to deformation. Since the cut off portions 34 are
provided in the liner supports 13, the stress produced in the
lining plate 11 may be sufficiently relieved. That is, at the cut
off portions 34, the lining plate 11 is free to bend itself.
Therefore the lining plate 11 may be prevented from being damaged,
and the joint between the lining plate 11 and the flange 22 may be
also prevented from being damaged. Thus the air- and
water-tightness of the containment vessel 1 may be maintained.
As described hereinbefore, according to the present invention,
cracking of the concrete foundation as well as breaking of the
lining plate may be prevented so that the safety of the containment
vessel may be much improved. Furthermore the step of tightening the
anchor bolts may be eliminated.
Second Embodiment, FIG. 6
The second embodiment shown in FIG. 6 is substantially similar in
construction to the first embodiment described hereinbefore except
additional concrete blocks 40 are placed upon the base plate 20 in
the annular recess 26 outside of the containment vessel 1 to
prevent the nuts of the anchor bolts 5 from loosening. The concrete
blocks 40 are spaced apart from the outer side wall of the annular
recess 26 so that sand in the pit portion 9 may fill the space
therebetween. The height of the concrete block 40 is selected so as
to be greater than the depth of the annular recess 26 to extend
into the pit portion 9.
Third Embodiment, FIG. 7
The third embodiment shown in FIG. 7 is substantially similar to
the second embodiment shown in FIG. 5 except that the concrete
blocks 40 fill the annular recess 26 outside of the containment
vessel 1 upon the base plate 20 thereof, thereby forming the bottom
of the pit portion 9. Between the outer side wall of the annular
recess 26 and the concrete blocks 40 are interposed intermediate
members 42 similar to the intermediate members 38 between the inner
wall of the annular recess 26 and the inner concrete block 36
inside the containment vessel 1.
So far the present invention has been described as being applied to
the nuclear reactor containment vessel, but it is understood that
the present invention may be also applied to pressure vessels for
storing therein semi-finished products or the like which may
produce heat and/or gas, whereby the internal pressure may be
increased. It is also understood that various modifications can be
effected without departing from the true spirit of the present
invention.
* * * * *