U.S. patent application number 12/600774 was filed with the patent office on 2010-06-17 for preventive maintenance/repair device and preventive maintenance/repair method for cylindrical structure.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Hisashi Hozumi, Mitsuaki Shimamura, Yutaka Togasawa, Yasuhiro Yuguchi.
Application Number | 20100150296 12/600774 |
Document ID | / |
Family ID | 40032013 |
Filed Date | 2010-06-17 |
United States Patent
Application |
20100150296 |
Kind Code |
A1 |
Togasawa; Yutaka ; et
al. |
June 17, 2010 |
PREVENTIVE MAINTENANCE/REPAIR DEVICE AND PREVENTIVE
MAINTENANCE/REPAIR METHOD FOR CYLINDRICAL STRUCTURE
Abstract
A preventive maintenance/repair device 10 of the present
invention includes: a device body 11, and holding mechanisms 13a
and 13b connected to the device body 11, the holding mechanisms 13a
and 13b being configured to hold the device body 11 on an outer
circumferential surface of a cylindrical structure 19. Further, the
device body 11 is equipped with a traveling and driving part
configured to be circumferentially movable along the outer
circumferential surface of the cylindrical structure 19.
Furthermore, each of the holding mechanisms 13a and 13b is equipped
with a maintenance/repair mechanism 16 configured to maintain and
repair the cylindrical structure 19.
Inventors: |
Togasawa; Yutaka;
(Kanagawa-ken, JP) ; Shimamura; Mitsuaki;
(Saitama-ken, JP) ; Hozumi; Hisashi; (Tokyo,
JP) ; Yuguchi; Yasuhiro; (Kanagawa-ken, JP) |
Correspondence
Address: |
FOLEY AND LARDNER LLP;SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
|
Family ID: |
40032013 |
Appl. No.: |
12/600774 |
Filed: |
May 22, 2008 |
PCT Filed: |
May 22, 2008 |
PCT NO: |
PCT/JP2008/059449 |
371 Date: |
November 18, 2009 |
Current U.S.
Class: |
376/260 |
Current CPC
Class: |
G21C 19/207 20130101;
G21C 17/017 20130101; Y02E 30/30 20130101 |
Class at
Publication: |
376/260 |
International
Class: |
G21C 19/02 20060101
G21C019/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2007 |
JP |
2007-135302 |
Claims
1. A preventive maintenance/repair device for use in maintaining
and repairing a cylindrical structure of a cylindrical shape among
reactor internal structures installed in a reactor pressure vessel,
the preventive maintenance/repair device comprising: a device body;
a holding mechanism connected to the device body, the holding
mechanism being configured to hold the device body on an outer
circumferential surface of the cylindrical structure; a traveling
and driving part disposed on the device body, the traveling and
driving part being configured to be circumferentially movable along
the outer circumferential surface of the cylindrical structure; and
a maintenance/repair mechanism disposed on the holding mechanism,
the maintenance/repair mechanism being configured to maintain and
repair the cylindrical structure.
2. The preventive maintenance/repair device according to claim 1,
wherein the holding mechanism includes: a pair of arms each having
a shape along the outer circumferential surface of the cylindrical
structure; guide rollers respectively disposed on distal ends of
the pair of arms; arm cylinders configured to respectively drive
the pair of arms; and links connected between the arms and the arm
cylinders, the links being configured to transmit drives of the arm
cylinders to the arms.
3. The preventive maintenance/repair device according to claim 2,
wherein each of the arms of the holding mechanism is separable into
a proximal arm body and a distal arm end, and in order to hold the
device body on an outer circumferential surface of another
cylindrical structure of a different outer diameter, the arm end
can be replaced with another arm end of a different length with
respect to the arm body.
4. The preventive maintenance/repair device according to claim 2,
wherein each of the arms of the holding mechanism is separable into
a proximal arm body and a distal arm end, and in order to hold the
device body on an outer circumferential surface of another
cylindrical structure of a different outer diameter, the arm body
can be replaced with another arm body of a different length with
respect to the device body.
5. The preventive maintenance/repair device according to claim 1,
wherein a distance sensor is disposed on an outer surface of the
device body on a side opposed to a surrounding structure.
6. The preventive maintenance/repair device according to claim 1,
wherein the maintenance/repair mechanism includes an equipment
configured to maintain and repair the cylindrical structure, and an
equipment cylinder configured to drive the equipment in a
longitudinal direction of the cylindrical structure.
7. A preventive maintenance/repair device for use in maintaining
and repairing a cylindrical structure of a cylindrical shape among
reactor internal structures installed in a reactor pressure vessel,
the preventive maintenance/repair device comprising: a device body;
a holding mechanism connected to the device body, the holding
mechanism being configured to hold the device body on an outer
circumferential surface of the cylindrical structure; a traveling
and driving part disposed on the device body, the traveling and
driving part being configured to be circumferentially movable along
the outer circumferential surface of the cylindrical structure; and
a maintenance/repair mechanism disposed on the device body, the
maintenance/repair mechanism being configured to maintain and
repair the cylindrical structure; wherein the device body is
provided with a thruster driving part configured to move the device
body in water.
8. A preventive maintenance/repair method using a
maintenance/repair device for use in maintaining and repairing a
cylindrical structure of a cylindrical shape among reactor internal
structures installed in a reactor pressure vessel, the preventive
maintenance/repair device comprising: a device body; a holding
mechanism connected to the device body, the holding mechanism being
configured to hold the device body on an outer circumferential
surface of the cylindrical structure; a traveling and driving part
disposed on the device body, the traveling and driving part being
configured to be circumferentially movable along the outer
circumferential surface of the cylindrical structure; and a
maintenance/repair mechanism disposed on the holding mechanism, the
maintenance/repair mechanism being configured to maintain and
repair the cylindrical structure; wherein the device body is
provided with an access device configured to bring the device body
closer to the cylindrical structure so as to attach the device body
to the outer circumferential surface of the cylindrical structure
and to detach therefrom the device body, and an operation pole is
connected to the access device, the preventive maintenance/repair
method comprising the steps of: mounting the access device and the
operation pole on the device body; sending the device body into the
reactor pressure vessel in a hanging manner through the operation
pole and bringing the device body closer to the cylindrical
structure; holding the device body on the outer circumferential
surface of the cylindrical body by the holding mechanism; removing
the access device from the device body, after the device body has
been held on the cylindrical structure by the holding mechanism;
and performing a maintenance/repair operation to the cylindrical
structure by the maintenance/repair mechanism.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a preventive
maintenance/repair device and a preventive maintenance/repair
method for a cylindrical structure of a cylindrical shape among
reactor internal structures installed in a reactor pressure
vessel.
BACKGROUND ART
[0002] Generally, a reactor internal structure installed in a
reactor pressure vessel 1 is formed of a material having an
excellent corrosion resistance and a mechanical strength under a
high temperature and a high pressure environment, such as an
austenitic stainless steel and a nickel based alloy. However, even
a reactor internal structure formed of such a material may suffer
from a material deterioration which is caused by a lengthy
operation under a high temperature and a high pressure environment
and by an irradiation of neutron. In particular, in a portion near
a welding part of the reactor internal structure, when a heat is
generated upon welding, a material of the portion may be sensitized
or a tensile residual stress may be generated so that a stress
corrosion cracking may possibly occur. In this case, it is
difficult to change the reactor internal structure for another,
which poses a serious problem in terms of maintenance and
administration.
[0003] An overall structure of the reactor internal structure
installed in the reactor pressure vessel 1 in a boiling water
reactor electric-power plant (hereinafter referred to as "BWR
plant") is described with reference to FIG. 9. A shroud 2
supporting a fuel assembly is disposed inside the reactor pressure
vessel 1. A jet pump 3 is disposed on a part (annulus part) between
an inner wall of the reactor pressure vessel 1 and the shroud 2. In
addition, disposed on a lower part of the reactor pressure vessel 1
is a control-rod drive mechanism housing 4, and disposed on an
upper part of the reactor pressure vessel 1 is a core spray pipe 48
(hereinafter referred to as "CS pipe").
[0004] As shown in FIG. 10, the jet pump 3 includes: a riser pipe 8
located on a side where a coolant is taken in; a mixer nozzle 7
located above the riser pipe 8 and connected to an upper end of the
riser pipe 8; and an inlet mixer 5 connected to a lower end of the
mixer nozzle 7. A diffuser 6 is connected to a lower end of the
inlet mixer 5. In order to support the riser pipe 8 on the inner
wall of the reactor pressure vessel 1, a riser brace 9 is mounted
on the inner wall of the reactor pressure vessel 1.
[0005] Various maintenance/repair devices have been proposed for
maintaining and repairing such a reactor internal structure.
[0006] At first, there is described a case in which an outer
surface of the jet pump 3 is maintained and repaired. In this case,
a maintenance/repair device is firstly fitted onto a distal end of
a cable or a distal end of an articulated operation pole, and the
maintenance/repair device is sent into the reaction pressure vessel
1 from the upper part thereof in a hanging manner. Then, the
maintenance/repair device is fixed on a reactor internal structure
above the jet pump 3 or the riser brace 9. Thereafter, a target
region is subjected to a maintaining and repairing operation by the
maintenance/repair device. Such a maintenance/repair device is
disclosed in JP11-109081A and JP2002-148385A.
[0007] Next, there is described a case in which an inner surface of
the jet pump 3 is maintained and repaired. In this case, the inlet
mixer 5 is firstly removed. Then, the maintenance/repair device is
sent into the reaction pressure vessel 1 from the upper part
thereof in a hanging manner. Then, the maintenance/repair device is
inserted into the jet pump 3. Thereafter, a target region is
subjected to a maintaining and repairing operation by the
maintenance/repair device. In an alternative method, the
maintenance/repair device is inserted into the diffuser 6 from the
lower part of the reaction pressure vessel 1, and a target region
is subjected to a maintaining and repairing operation. Such a
maintenance/repair device is disclosed in JP5-209864A and
JP2003-185784A.
[0008] Next, there is described a case in which the inner surface
of the jet pump 3 is maintained and repaired without removing the
inlet mixer 5. In this case, the maintenance/repair device is
inserted into a gap formed in an opening of the mixer nozzle 7, and
a target region is subjected to a maintaining and repairing
operation. Such a maintenance/repair device is disclosed in
JP2001-65778A, JP2002-311183A, and JP2004-251894A.
[0009] However, the aforementioned maintenance/repair devices are
intended to maintain and repair the diffuser 6 which is a part of
the jet pump 3, and thus cannot maintain and repair the inside and
the outside of the riser pipe 8.
[0010] Next, there is described a case in which a wall of the
shroud 2 is maintained and repaired. In this case, a
maintenance/repair device is inserted into the annulus part from
the upper part of the reactor pressure vessel 1. Alternatively, the
maintenance/repair device is inserted from the upper part of the
reactor pressure vessel 1 through an upper lattice plate 47
disposed above the shroud 2. Thereafter, a target region is
subjected to a maintaining and repairing operation by the
maintenance/repair device. Such maintenance/repair device are
disclosed in JP Patent Nos. 3288924, 3075952, and 3069005, and
JP11-174192A. However, the maintenance/repair devices are intended
to maintain and repair the wall of the shroud 2, and thus cannot
maintain and repair another reactor internal structure in the
reactor pressure vessel 1, in particular, a cylindrical structure
such as a pipe.
[0011] Next, there is described a case in which a bottom part of
the reactor pressure vessel 1 is maintained and repaired. Such
maintenance/repair devices are disclosed in JP2002-651159A and JP
Patent No. 3011583. Although these maintenance/repair devices are
advantageous in their small dimensions and free movableness in
water, the maintenance/repair devices cannot maintain and repair
the outer surface and the inner surface of the jet pump 3, because
the space of the annulus part is further narrower.
[0012] Almost all the above-described maintenance/repair devices
are sent into the reactor pressure vessel 1 from the upper part
thereof through a cable or a wire in a hanging manner, and are
brought closer to a cylindrical structure such as a pipe installed
in the reactor pressure vessel 1 so as to be fixed onto the outer
surface of the cylindrical structure. When the maintenance/repair
device is fixed onto the inner surface of the cylindrical
structure, a plurality of arms of the maintenance/repair device are
expanded in a radial direction of the inner surface of the
cylindrical structure. Thus, the plurality of arms are pressed onto
the inner surface of the cylindrical structure, whereby the
maintenance/repair device can be fixed thereon.
[0013] When the aforementioned maintenance/repair device is fixed
onto the outer surface of the cylindrical structure, since there
are various cylindrical structures of different shapes and
different dimensions, it is necessary to change the structure or
the configuration of the maintenance/repair device in accordance
with a target region to be maintained and repaired. Thus, the
structure of the maintenance/repair device is complicated, and the
size of the maintenance/repair device is further enlarged.
DISCLOSURE OF THE INVENTION
[0014] The present invention has been made in view of the above
circumstances. The object of the present invention is to provide: a
preventive maintenance/repair device that is capable of precisely,
circumferentially moving along an outer circumferential surface of
a cylindrical structure of a cylindrical shape among reactor
internal structures installed in a reactor pressure vessel, and of
being securely held on the outer circumferential surface of the
cylindrical structure, so as to maintain and repair the cylindrical
structure; and a preventive maintenance/repair method thereof.
[0015] The present invention is a preventive maintenance/repair
device for use in maintaining and repairing a cylindrical structure
of a cylindrical shape among reactor internal structures installed
in a reactor pressure vessel, the preventive maintenance/repair
device comprising: a device body; a holding mechanism connected to
the device body, the holding mechanism being configured to hold the
device body on an outer circumferential surface of the cylindrical
structure; a traveling and driving part disposed on the device
body, the traveling and driving part being configured to be
circumferentially movable along the outer circumferential surface
of the cylindrical structure; and a maintenance/repair mechanism
disposed on the holding mechanism, the maintenance/repair mechanism
being configured to maintain and repair the cylindrical
structure.
[0016] The present invention is the preventive maintenance/repair
device wherein the holding mechanism includes: a pair of arms each
having a shape along the outer circumferential surface of the
cylindrical structure; guide rollers respectively disposed on
distal ends of the pair of arms; arm cylinders configured to
respectively drive the pair of arms; and links connected between
the arms and the arm cylinders, the links being configured to
transmit drives of the arm cylinders to the arms.
[0017] The present invention is the preventive maintenance/repair
device wherein each of the arms of the holding mechanism is
separable into a proximal arm body and a distal arm end, and in
order to hold the device body on an outer circumferential surface
of another cylindrical structure of a different outer diameter, the
arm end can be replaced with another arm end of a different length
with respect to the arm body.
[0018] The present invention is the preventive maintenance/repair
device wherein each of the arms of the holding mechanism is
separable into a proximal arm body and a distal arm end, and in
order to hold the device body on an outer circumferential surface
of another cylindrical structure of a different outer diameter, the
arm body can be replaced with another arm body of a different
length with respect to the device body.
[0019] The present invention is the preventive maintenance/repair
device wherein a distance sensor is disposed on an outer surface of
the device body on a side opposed to a surrounding structure.
[0020] The present invention is the preventive maintenance/repair
device wherein a distance sensor is disposed on an outer surface of
the device body on a side opposed to a surrounding structure.
[0021] The present invention is the preventive maintenance/repair
device wherein the maintenance/repair mechanism includes an
equipment configured to maintain and repair the cylindrical
structure, and an equipment cylinder configured to drive the
equipment in a longitudinal direction of the cylindrical
structure.
[0022] The present invention is the preventive maintenance/repair
device wherein the equipment of the maintenance/repair mechanism is
formed of an ultrasonic flaw-detecting probe.
[0023] The present invention is the preventive maintenance/repair
device wherein the equipment of the maintenance/repair mechanism is
a camera for a visual observation.
[0024] The present invention is the preventive maintenance/repair
device wherein the equipment of the maintenance/repair mechanism is
a polishing jig.
[0025] The present invention is the preventive maintenance/repair
device wherein the device body is provided with an access device
configured to bring the device body closer to the cylindrical
structure so as to attach the device body to the outer
circumferential surface of the cylindrical structure and to detach
therefrom the device body, and an operation pole is connected to
the access device,
[0026] The present invention is the preventive maintenance/repair
device wherein the access device includes: an access-device holding
part engageable with the device body; and a rotating and driving
part interposed between the operation pole and the access-device
holding part, the rotating and driving part being configured to
rotate the device body and the access-device holding part with
respect to the operation pole.
[0027] The present invention is a preventive maintenance/repair
device for use in maintaining and repairing a cylindrical structure
of a cylindrical shape among reactor internal structures installed
in a reactor pressure vessel, the preventive maintenance/repair
device comprising: a device body; a holding mechanism connected to
the device body, the holding mechanism being configured to hold the
device body on an outer circumferential surface of the cylindrical
structure; a traveling and driving part disposed on the device
body, the traveling and driving part being configured to be
circumferentially movable along the outer circumferential surface
of the cylindrical structure; and a maintenance/repair mechanism
disposed on the device body, the maintenance/repair mechanism being
configured to maintain and repair the cylindrical structure;
wherein the device body is provided with a thruster driving part
configured to move the device body in water.
[0028] The present invention is the preventive maintenance/repair
device wherein a buoyant member is located in one of the device
body and the maintenance/repair mechanism.
[0029] The present invention is a preventive maintenance/repair
method comprising the steps of: mounting the access device and the
operation pole on the device body; sending the device body into the
reactor pressure vessel in a hanging manner through the operation
pole and bringing the device body closer to the cylindrical
structure; holding the device body on the outer circumferential
surface of the cylindrical body by the holding mechanism; removing
the access device from the device body, after the device body has
been held on the cylindrical structure by the holding mechanism;
and performing a maintenance/repair operation to the cylindrical
structure by the maintenance/repair mechanism.
[0030] According to the present invention, the preventive
maintenance/repair device can be securely held on the outer
circumferential surface of the cylindrical structure in the reactor
pressure vessel. In addition, the maintenance/repair device can be
circumferentially moved on the outer circumferential surface of the
cylindrical structure. Thus, the maintenance/repair device can be
precisely moved to a target region of the outer circumferential
surface of the cylindrical structure, so that the outer
circumferential surface of the cylindrical structure can be
maintained and repaired.
[0031] According to the present invention, the preventive
maintenance/repair device can be securely held on the outer
circumferential surface of the cylindrical structure in the reactor
pressure vessel. In addition, the maintenance/repair device can be
circumferentially moved on the outer circumferential surface of the
cylindrical structure. In addition, the maintenance/repair device
can be moved in water. Thus, the maintenance/repair device can be
precisely moved to a target region of the outer circumferential
surface of the cylindrical structure, so that the outer
circumferential surface of the cylindrical structure can be
maintained and repaired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is an overall structural view for explaining a
preventive maintenance/repair device in a first embodiment of the
present invention.
[0033] FIG. 2 is a view for explaining a method of determining an
initial holding position at which the preventive maintenance/repair
device in the first embodiment of the present invention is
held.
[0034] FIG. 3 is a structural view for explaining a traveling and
driving part in the first embodiment of the present invention.
[0035] FIG. 4 is a structural view for explaining a
maintenance/repair mechanism in the first embodiment of the present
invention.
[0036] FIG. 5 is a structural view for explaining an access device
in the first embodiment of the present invention.
[0037] FIG. 6 is a view for explaining the connection of an
operation pole to the access device in the first embodiment of the
present invention.
[0038] FIG. 7 is an overall structural view for explaining a
preventive maintenance/repair device in a second embodiment of the
present invention.
[0039] FIG. 8 is a structural view for explaining a thruster
driving part in the second embodiment of the present invention.
[0040] FIG. 9 is a structural view for explaining an inside of a
reactor pressure vessel in a boiling water reactor.
[0041] FIG. 10 is a structural view showing a jet pump in the
boiling water reactor.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
[0042] Embodiments of the present invention will be described
herebelow with reference to the accompanying drawings. FIGS. 1 to 6
show a preventive maintenance/repair device in a first embodiment
of the present invention. FIGS. 1(a) and 1(b) are overall
structural views for explaining the preventive maintenance/repair
device. FIGS. 2(a) and 2(b) are views for explaining a method of
determining an initial holding position at which the preventive
maintenance/repair device is held. FIGS. 3(a) and 3(b) are
structural views for explaining a traveling and driving part. FIGS.
4(a), 4(b), 4(c), and 4(d) are structural views for explaining a
maintenance/repair mechanism. FIG. 5 is a view for explaining an
access device. FIG. 6 is a view for explaining the connection of an
operation pole to the access device.
[0043] At first, a preventive maintenance/repair device 10 in the
first embodiment of the present invention is described with
reference to FIGS. 1(a) and 1(b). FIG. 1(a) is a plan view of the
overall structure for explaining the preventive maintenance/repair
device 10, and FIG. 1(b) is a front view of the overall structure
for explaining the preventive maintenance/repair device 10. The
preventive maintenance/repair device 10 in this embodiment is a
device for cleaning, checking, inspecting, maintaining, and
repairing an outer surface of a cylindrical structure 19 of a
cylindrical shape such as a pipe among reactor internal structures
installed in a reactor pressure vessel 1 in a BWR plant. In
particular, target regions are welding portions of a jet pump 3, a
core spray pipe 48 (hereinafter referred to as "CS pipe"), and a
control-rod drive mechanism housing 4 (hereinafter referred to as
"CRD housing"), which are generically referred to as a cylindrical
structure 19 installed in the reactor pressure vessel 1.
[0044] At first, the overall structure of the preventive
maintenance/repair device 10 in this embodiment is described with
reference to FIGS. 1(a) and 1(b). The preventive maintenance/repair
device 10 includes: a device body 11; a pair of holding mechanisms
13a and 13b connected to the device body 11, the holding mechanism
13a and 13b being capable of holding the device body 11 on an outer
circumferential surface of the cylindrical structure 19; and a
traveling and driving part 20 disposed on the device body 11, the
traveling and driving part 20 being capable of circumferentially
moving along the outer circumferential surface of the cylindrical
structure 19. Each of the holding mechanisms 13a and 13b is
provided with a maintenance/repair mechanism 16 that maintains and
repairs the cylindrical structure 19.
[0045] The pair of holding mechanisms 13a and 13b respectively
include: a pair of arms 12a and 12b each having a shape along the
outer circumferential surface of the cylindrical structure 19; and
guide rollers 14a and 14b disposed on distal ends of the pair of
arms 12a and 12b. Respectively connected to the pair of arms 12a
and 12b are arm cylinders 17a and 17b and arm cylinders 17c and 17d
for driving the arms 12a and 12b pneumatically or hydraulically.
The arm 12a and the arm cylinders 17a and 17b are connected by a
link 18a, and the arm 12b and the arm cylinders 17c and 17d are
connected by a link 8b, the links 18a and 18b being configured to
transmit the driving force of the arm cylinders 17a and 17b and the
driving force of the arm cylinders 17c and 17d to the arms 12a and
12b. The arms 12a and 12b can be removed from the connection
portions of the links 18a and 18b, so that arm bodies 49a and 49b
and arm ends 49c and 49d can be replaced with other arm bodies 49a
and 49b of different lengths and other arm ends 49c and 49d of
different lengths so as to correspond to a different outer diameter
of another cylindrical structure 19.
[0046] In addition, the arms 12a and 12b of the holding mechanisms
13a and 13b respectively have lengths corresponding to the outer
diameter of the cylindrical structure 19. The arms 12a and 12b
respectively include: the arm bodies 49a and 49b disposed on the
side of the device body 11 (on the proximal side); and the arm ends
49c and 49d that are disposed on distal ends of the arm bodies 49a
and 49b so as to be separable therefrom. Thus, in order to hold the
device body 11 on an outer circumferential surface of another
cylindrical structure 19 of a different outer diameter, the arm
ends 49c and 49d of the arms 12a and 12b are replaceable with other
arm ends 49c and 49d having lengths different from those of the
former arm ends 49c and 49d so as to correspond to the different
outer diameter of the other cylindrical structure 19.
[0047] As shown in FIGS. 2(a) and 2(b), a distance sensor 28 is
disposed on an outer surface of the device body 11 on a side
opposed to a surrounding structure. The distance sensor 28 is
formed of an ultrasonic distance sensor, and is capable of
measuring a distance between the distance sensor 28 and a
surrounding structure. FIG. 2(a) shows a state before an initial
holding position at which the preventive maintenance/repair device
10 is held on the cylindrical structure 19 is not determined yet,
and FIG. 2(b) shows a state after the initial holding position of
the preventive maintenance/repair device 10 has been determined and
the preventive maintenance/repair device 10 is held on the initial
holding position.
[0048] As shown in FIGS. 3(a) and 3(b), the traveling and driving
part 20 disposed on the device body 11 includes a traveling wheel
21 that is driven in rotation in contact with the outer
circumferential surface of the cylindrical structure 19, and a
motor 26 that drives the traveling wheel 21 in rotation. FIG. 3(a)
is a front view for explaining the traveling and driving part 20,
and FIG. 3(b) is a bottom view of the traveling and driving part
20. A shaft 25 is connected to the traveling wheel 21, and a gear
22 is connected to the shaft 25. The gear 22 is connected to an
output shaft of the motor 26 via gears 23 and 24. Further,
connected to the motor 26 are cables 27a and 27b for remotely
operating the motor 26. The traveling and driving part 20 is
removably mounted on the device body 11.
[0049] As shown in FIGS. 4(a), 4(b), 4(c), and 4(d), the
maintenance/repair mechanism 16 includes an equipment 15 that
maintains and repairs the cylindrical structure 19, and an
equipment cylinder 30 that drives the equipment 15 in a
longitudinal direction of the cylindrical body 19. FIG. 4(a) is a
front view for explaining a state in which the equipment 15 of the
maintenance/repair mechanism 16 is held at an upper position, FIG.
4(b) is a side view for explaining a state in which the equipment
15 of the maintenance/repair mechanism 16 is held at the upper
position, FIG. 4(c) is a front view for explaining the equipment 15
of the maintenance/repair mechanism 16 is held at a lower position,
and FIG. 4(d) is a side view for explaining the equipment 15 of the
maintenance/repair mechanism 16 at the lower position.
[0050] As shown in FIGS. 4(a), 4(b), 4(c), and 4(d), a plate 29 is
removably mounted on the arm 12b of the holding mechanism 13b. The
plate 29 has an equipment cylinder 30 and a slide guide 31. The
equipment 15 is mounted on the slide guide 31 via a plate 32b.
Fixed via a plate 32a on a surface of the equipment 15 which is
opposed to the surface on which the plate 32b is disposed is an
L-shaped fitting 33 to be connected to an end of a shaft of the
equipment cylinder 30.
[0051] As shown in FIGS. 4(a), 4(b), 4(c), and 4(d), the arm 12b is
provided with a cutout 12c corresponding to the maintenance/repair
mechanism 16. Although not shown, the other arm 12a, which is
disposed on the side opposite to the arm 12b with respect to the
cylindrical structure 19, is provided with the same cutout 12c.
Thus, the maintenance/repair mechanism 16 can be mounted not only
on the arm 12b but also on the arm 12a.
[0052] In FIGS. 4(a), 4(b), 4(c), and 4(d), although the cutout 12c
of the arm 12b faces downward, the cutout 12c may be formed to face
upward. Thus, in FIGS. 4(a), 4(b), 4(c), and 4(d), the
maintenance/repair mechanism 16 can be mounted on the arm 12b to
face downward or upward. Similarly, in FIGS. 4(a), 4(b), 4(c), and
4(d), the maintenance/repair mechanism 16 can be mounted on the arm
12a to face downward or upward.
[0053] The equipment 15 of the maintenance/repair mechanism 16 is
formed of an ultrasonic flaw-detecting probe, such as a
phased-array UT probe, which can ultrasonically detect a flaw such
as a crack of the cylindrical structure 19 without contacting the
cylindrical structure 19.
[0054] Alternatively, the equipment 15 of the maintenance/repair
mechanism 16 may be a camera for a visual observation. Further, the
equipment 15 of the maintenance/repair mechanism 16 may be a
polishing jig.
[0055] As shown in FIG. 5, the device body 11 is equipped with an
access device 34 that brings the device body 11 closer to the
cylindrical structure 19 so as to attach the device body 11 to the
outer circumferential surface of the cylindrical structure 19 and
to detach therefrom the device body 11. In addition, connected to
the access device 34 is an operation pole 46 via a connection part
45.
[0056] The access device 34 includes: an access-device holding part
35 engageable with the device body 11; and a rotating and driving
part 36 interposed between the connection part 45 on the side of
the operation pole 46 and the access-device holding part 35, the
rotating and driving part 36 being capable of rotating the device
body 11 and the access-device holding part 35 with respect to the
connection part 45 and the operation pole 46.
[0057] The access-device holding part 35 includes a plurality of
device-body side pins 35a to be inserted into a plurality of holes
formed in the device body 11, holding pins 35b for holding the
device-body side pins 35a, and holding cylinder 37 for pressing the
holding pins 35b onto the device-body side pins 35a via fittings
35c.
[0058] The rotating and driving part 36 includes a frame 38
rotatably connected to the access-device holding part 35 through a
pin 42, and a rotational cylinder 40. A fixed side of the
rotational cylinder 40 is rotatably connected to the frame 38
through a pin 39, and an end of a shaft 43 is rotatably connected
to a fixed side of the holding cylinder 37 through a pin 44. The
frame 38 has the connection part 45 to which the operation pole 46
can be connected.
[0059] As shown in FIG. 6, the operation pole 46 is composed of an
operation pole 46a and an operation pole 46b. The operation pole
46a is connected to the connection part 45 of the frame 38 (see,
FIG. 5), and the operation pole 46a and the operation pole 46b are
connected to each other.
[0060] Next, an operation of this embodiment as structured above is
described. Given herein as an example to describe the process is a
case where a pipe installed vertically in the reactor pressure
vessel 1 is maintained and repaired.
[0061] How to fit the access device 34 on the device body 11 is
described with reference to FIG. 5. At this time, the plurality of
device-body side pins 35a of the access-device holding part 35
disposed on the access device 34 are firstly inserted into the
plurality of holes formed in the device body 11. Then, the holding
cylinders 37 of the rotating and driving part 36 are driven so as
to press the holding pins 35b onto the device-body side pins 35a
via the fittings 35c. Thus, the device body 11 can be held by the
access device 34, without the device-body side pins 35a coming off
from the holes formed in the device body 11.
[0062] Next, how to fit the operation pole 46a on the connection
part 45 of the frame 38 (see, FIG. 5) disposed on the access device
34 is described with reference to FIG. 6. At this time, one end of
the operation pole 46a is connected to the connection part 45 of
the frame 38 of the rotating and driving part 36 of the access
device 34. Then, the operation pole 46b is connected to the other
end of the operation pole 46a.
[0063] Thereafter, the device body 11 hanging from the operation
pole 46 composed of the operation poles 46a and 46b is sent into
the reactor pressure vessel 1, and is brought closer to the
cylindrical structure 19. At this time, as shown in FIG. 5, the
rotation cylinder 40 of the rotating and driving part 36 of the
access device 34 is driven so as to contract the shaft 43 of the
rotation cylinder 40. Thus, the device body 11 and the
access-device holding part 35 are rotated with respect to the
operation pole 46a, so that the device body 11 is oriented in
substantially the same direction as the longitudinal direction of
the operation poles 46a and 46b.
[0064] Then, as shown in FIG. 6, the preventive maintenance/repair
device 10, which is held by the operation poles 46a and 46b
connected to the access device 34, is sent in the hanging manner
via the access device 34. After that, the preventive
maintenance/repair device 10 is sent into the reactor pressure
vessel 1 through the lateral side of the CS pipe 48, and is brought
closer to a target region of the cylindrical structure 19.
[0065] Then, as shown in FIG. 5, the rotation cylinder 40 is driven
so as to extend the shaft 43 of the rotation cylinder 40. Thus, the
device body 11 and the access-device holding part 35 are rotated
with respect to the operation pole 46a, so that the device body 11
is oriented in a direction substantially perpendicular to the
longitudinal direction of the operation poles 46a and 46b.
[0066] Then, the device body 11 is held by the holding mechanism 13
on the outer circumferential surface of the cylindrical structure
19. At this time, as shown in FIG. 1(a), the traveling wheel 21 of
the traveling and driving part 20 is in contact with the outer
circumferential surface of the cylindrical structure 19. In
addition, by driving the arm cylinder 17a, 17b, 17c, and 17d of the
holding mechanisms 13a and 13b, the guide rollers 14a and 14b
disposed on the distal ends of the arms 12a and 12b are pressed
onto the outer circumferential surface of the cylindrical structure
19 via the links 18a and 18b and the arms 12a and 12b. Thus, the
preventive maintenance/repair device 10 is held on the outer
circumferential surface of the cylindrical structure 19.
[0067] In a case in which another cylindrical structure 19 of a
different outer diameter is maintained and repaired, the arm ends
49c and 49d of the arms 12a and 12b are previously replaced with
other arm ends 49c and 49d so that the arms 12a and 12b have the
lengths corresponding to the outer diameter of this cylindrical
structure 19. Thus, the preventive maintenance/repair device 10 can
be securely held on the cylindrical structure 19 of a given outer
diameter.
[0068] As described above, after the device body 11 has been held
on the cylindrical structure 19 by the arms 12a and 12b of the
holding mechanism 13, the access device 34 is removed from the
device body 11. At this time, the holding cylinder 37 of the
access-device holding part 35 is driven so as to move the holding
pins 35b via the fittings 35c from the device-body side pins 35a to
a side opposed to the device-body side pins 35a. Then, the
access-device holding part 35 hanging from the operation poles 46a
and 46b is moved upward of the reactor pressure vessel 11. Thus,
the plurality of device-body side pins 35a can be drawn out from
the plurality of holes formed in the device body 11. Thereafter,
the access device 34 is moved further upward of the reactor
pressure vessel 1 in the hanging manner by means of the operation
poles 46a and 46b, and the access device 34 is withdrawn.
[0069] Then, the preventive maintenance/repair device 10 is
circumferentially moved along the outer circumferential surface of
the cylindrical structure 19. In this case, a drive command is
firstly given from a remote location to the motor 26 of the
traveling and driving part 20 through the cables 27a and 27b. At
this time, the motor 26 is driven, so that the rotational force of
the motor 26 is transmitted to the shaft 25 via the gear 24, the
gear 23, and the gear 22. The rotational force of the shaft 25 is
transmitted to the traveling wheel 11 connected to the shaft 25, so
that the traveling wheel 11 is drive in rotation. Thus, the
preventive maintenance/repair device 10 can be circumferentially
moved along the outer circumferential surface of the cylindrical
structure 19.
[0070] When the preventive maintenance/repair device 10 is
circumferentially moved along the outer circumferential surface of
the cylindrical structure 19, the guide rollers 14a and 14b
disposed on the distal ends of the arms 12a and 12b of the holding
mechanisms 13a and 13b are rotated in accordance with the movement
of the preventive maintenance/repair device 10. Also at this time,
as described above, the guide rollers 14a and 14b are pressed onto
the outer circumferential surface of the cylindrical structure 19
by the arm cylinders 17a, 17b, 17c, and 17d of the holding
mechanisms 13a and 13b. Thus, the preventive maintenance/repair
device 10 can be smoothly, circumferentially moved along the outer
circumferential surface of the cylindrical structure 19, while the
preventive maintenance/repair device 10 is being held on the outer
circumferential surface of the cylindrical structure 19. As a
result, the equipment 15 of the maintenance/repair mechanism 16 can
be smoothly moved to a desired circumferential position along the
outer circumferential surface of the cylindrical structure 19.
[0071] The traveling and driving part 20 can be easily mounted on
and removed from the device body 11. Thus, if the traveling and
driving part 20 is broken for some reason or another, the whole
preventive maintenance/repair device 10 is drawn upward, and the
broken traveling and driving part 20 can be replaced with another
normal traveling and driving part 20, which has been prepared
beforehand, for a short period of time.
[0072] Then, as shown in FIGS. 2(a) and 2(b), there is determined
an initial position at which the preventive maintenance/repair
device 10 is held on the outer circumferential surface of the
cylindrical structure 19. The reason for determining the initial
position is as follows. In order to hold the preventive
maintenance/repair device 10 on the cylindrical structure 19, since
the space of the annulus part surrounding the cylindrical structure
19 is narrow, it is necessary to bring the preventive
maintenance/repair device 10 closer to a target region of the
cylindrical structure 19 from a direction in which the preventive
maintenance/repair device 10 does not interfere with a structure
surrounding the cylindrical structure 19. Thus, the direction in
which the preventive maintenance/repair device 10 is held varies
for each time, i.e., the direction in which the preventive
maintenance/repair device 10 is held is not constant.
[0073] During the operation, there is a possibility that the
preventive maintenance/repair device 10 is not held on a target
region of the cylindrical structure 19 so as to be detached from
the target region for some reason or another. In this case, the
equipment 15 of the maintenance/repair mechanism 16 is not
appropriately opposed to the outer circumferential surface of the
cylindrical structure 19. Under this state, the target region of
the cylindrical structure 19 cannot be precisely maintained and
repaired. It is difficult to exactly return the preventive
maintenance/repair device 10 to the original target region from
which the preventive maintenance/repair device 10 has been
detached. Even when the preventive maintenance/repair device 10 is
returned to a region near the original target region from which the
preventive maintenance/repair device 10 has been detached so as to
continue the maintenance/repair operation, there may remain some
region that could not be maintained and operated, between the
original target region from which the preventive maintenance/repair
device 10 has been detached and the region to which the preventive
maintenance/repair device 10 is returned.
[0074] In order to avoid this situation, in this embodiment, there
is determined an initial holding position at which the preventive
maintenance/repair device 10 is held on the outer circumferential
surface of the cylindrical structure 19. At this time, there is
used the distance sensor 28 which is disposed on the outer surface
of the device body 11 on a side opposed to the surrounding
structure, which is shown in FIGS. 2(a) and 2(b). At first, by
driving the motor 17 of the traveling and driving part 20, the
preventive maintenance/repair device 10 is circumferentially moved
along the outer circumferential surface of the cylindrical
structure 19, and a distance between the distance sensor 28 and the
surrounding structure is simultaneously measured. Then, there is
obtained a position of the preventive maintenance/repair device 10
at which the measured distance is shortest. The thus obtained
position is recorded, and the position is determined as an original
point of the initial holding position of the preventive
maintenance/repair device 10.
[0075] Below the guide roller 14a or 14b of the holding mechanism
13a or 13b, there are disposed a rotational sensor (not shown) that
measures an angle of a holding position of the preventive
maintenance/repair device 10, and a measurement wheel (not shown)
that rotates the rotational sensor. With the use of the rotational
sensor, an angle of the holding position of the preventive
maintenance/repair device 10 is measured. Thus, there can be
obtained an angle between the aforementioned original point and the
holding position of the preventive maintenance/repair device 10 at
which the preventive maintenance/repair device 10 has been
circumferentially moved along the outer circumferential surface of
the cylindrical structure 19 from the original point.
[0076] In this manner, an initial holding position of the
preventive maintenance/repair device 10 is determined. Thus, even
when the preventive maintenance/repair device 10 is detached from
the target region of the cylindrical structure 19 during the
maintaining and repairing operation, it is possible to specify the
position at which the preventive maintenance/repair device 10 has
been held before the preventive maintenance/repair device 10 is
detached therefrom. Accordingly, the maintaining and repairing
operation can be reliably performed both at the holding position in
the target region from which the preventive maintenance/repair
device 10 has been detached and at the holding position in the
target region to which the preventive maintenance/repair device 10
is returned.
[0077] Then, the equipment 15 of the maintenance/repair mechanism
16 is moved by the equipment cylinder 30 in the longitudinal
direction of the cylindrical structure 19. At this time, the shaft
of the equipment cylinder 30 for moving the equipment 15 in the
longitudinal direction of the cylindrical structure 19 is driven so
as to be expanded and contracted. Since the equipment 15 is
slidably disposed in the longitudinal direction of the cylindrical
structure 19 with respect to the fixed plate 29 by the slide guide
31, the expansion and contraction drive of the shaft of the
equipment cylinder 30 is transmitted to the equipment 15 via the
L-shaped fitting 33 and the plate 32a, so that the equipment 15 is
slid in the longitudinal direction of the cylindrical structure 19.
Thus, the equipment 15 can be precisely moved in the longitudinal
direction of the cylindrical structure 19 toward a target region of
the cylindrical structure 19.
[0078] Further, the plate 29 of the maintenance/repair mechanism 16
can be fixed not only to the arm 12b but also to the arm 12a.
Furthermore, the maintenance/repair mechanism 16 disposed to face
downward in FIGS. 4(a), 4(b), 4(c), and 4(d) may be disposed to
face upward in FIGS. 4(a), 4(b), 4(c), and 4(d). Thus, when a
working space in which the maintaining and repairing operation is
performed by the preventive maintenance/repair device 10 is
restricted, by changing the position and the direction of the
maintenance/repair mechanism 16, the maintaining and repairing
operation is performed over a wide range as much as possible by
effectively using the working space.
[0079] Then, by driving the motor 17 of the traveling and driving
part 20, the preventive maintenance/repair device 10 is
circumferentially moved along the outer circumferential surface of
the cylindrical structure 19. Thus, the equipment 15 can be
circumferentially moved along the outer circumferential surface of
the cylindrical structure 19. Accordingly, the cylindrical
structure 19 can be maintained and repaired by the equipment 15
over all the outer circumferential surface of the cylindrical
structure 19.
[0080] When the equipment 15 of the maintenance/repair mechanism 16
shown in FIGS. 4(a), 4(b), 4(c), and 4(d) is formed of an
ultrasonic flaw-detecting probe, a target region of the cylindrical
structure 19 can be ultrasonically detected. Thus, whether there is
a crack or not in a welding line of the cylindrical structure 19
can be checked.
[0081] Alternatively, the equipment 15 of the maintenance/repair
mechanism 16 is formed of a camera for a visual observation, the
appearance of the outer circumferential surface of the cylindrical
structure 19 can be visually checked.
[0082] In the above embodiment, there has been described the
maintaining and repairing operation which is performed when the
reactor pressure vessel 1 is filled with water. However, the
reactor pressure vessel 1 is not filled with water but with air,
the equipment 15 of the maintenance/repair mechanism 16 may be
replaced with another equipment so as to perform another
maintaining and repairing operation. Namely, when the equipment 15
is formed of a polishing jig, the outer circumferential surface of
the cylindrical structure 19 can be repaired. Alternatively, when
the equipment 15 is formed of a cleaning equipment such as a brush
or a water-cleaning nozzle, the outer circumferential surface of
the cylindrical structure 19 can be cleaned. Alternatively, when
the equipment 15 is formed of a maintenance equipment such as a
water-jet peening head or a laser peening head, the cylindrical
structure 19 can be maintained. Alternatively, when the equipment
15 is formed of a welding head or a grinding jig, the outer
circumferential surface of the cylindrical structure 19 can be
repaired.
[0083] According to this embodiment, the preventive
maintenance/repair device 10 can be securely held on the outer
circumferential surface of the cylindrical structure 19 installed
in the reactor pressure vessel 1. In addition, the preventive
maintenance/repair device 10 can be circumferentially moved on the
outer circumferential surface of the cylindrical structure 19.
Thus, the preventive maintenance/repair device 10 can be precisely
moved to a target region of the outer circumferential surface of
the cylindrical structure 19, so that the outer circumferential
surface of the cylindrical structure 19 can be maintained and
repaired.
Second Embodiment
[0084] Next, a preventive maintenance/repair device in a second
embodiment of the present invention is described with reference to
FIGS. 7 and 8. FIGS. 7(a) and 7(b) are overall structural views for
explaining the preventive maintenance/repair device. FIGS. 8(a) and
8(b) are structural views for explaining a thruster driving
part.
[0085] The second embodiment shown in FIGS. 7(a) and 7(b) and FIGS.
8(a) and 8(b) is embodied by applying a thruster driving part to
the first embodiment, and other structures of the second embodiment
are substantially the same as those of the first embodiment shown
in FIGS. 1 to 6.
[0086] In this embodiment, the parts and elements identical to
those of the first embodiment are shown by the same reference
numbers, and detailed description thereof is omitted. FIG. 7(a) is
a plan view of the overall structure for explaining the preventive
maintenance/repair device 100, and FIG. 7(b) is a front view of the
overall structure for explaining the preventive maintenance/repair
device 100. FIG. 8(a) is a structural view for explaining the
thruster driving part, and FIG. 8(b) is a structural view for
explaining a maintenance/repair mechanism 108. As shown in FIGS.
7(a) and 7(b), there are disposed: a device body 123; a pair of
holding mechanisms 104a and 104b connected to the device body 123,
the holding mechanisms 104 and 104b being capable of holding the
device body 123 on an outer circumferential surface of a
cylindrical structure 19; and a traveling and driving part 102
disposed on the device body 123, the traveling and driving part 102
being capable of circumferentially moving along the outer
circumferential surface of the cylindrical structure 19. Disposed
on a lower part of the device body 123 is a maintenance/repair
mechanism 108 that maintains and repairs the cylindrical structure
19. In addition, disposed on opposed side surfaces of the device
body 123 are a pair of thruster driving parts 106a and 106b that
moves the device body 123 in water.
[0087] The holding mechanisms 104a and 104b respectively include: a
pair of arms 103a and 103b each having a shape along the outer
circumferential surface of the cylindrical structure 19; and guide
rollers 105a and 105b disposed on distal ends of the pair of arms
103a and 103b. Respectively connected to the pair of arms 103a and
103b are arm cylinders 109a and 109b for driving the arms 103a and
the 103b pneumatically or hydraulically. The arm 103a and the arm
cylinder 109a, and the arm 103b and the arm cylinder 109b, are
respectively connected by links 110a and 110b that respectively
transmit driving forces of the arm cylinders 109a and 109b to the
arms 103a and 103b.
[0088] As shown in FIGS. 7(a) and 7(b), the traveling and driving
part 102 has a traveling wheel 101 which is driven in rotation,
while being in contact with the outer circumferential surface of
the cylindrical structure 19. Other structures are substantially
the same as those of the first embodiment shown in FIGS. 3(a) and
3(b). The traveling and driving part 102 is removably mounted on
the device body 123.
[0089] As shown in FIG. 8(a), the thruster driving parts 106a and
106b respectively include thrusters 114a and 114b, and motors 107a
and 107b for driving the thrusters 114a and 114b. Pulleys 113a and
113b are connected to output shafts of the motors 107a and 107b,
and pulleys 113j and 113k are connected to rotational shafts of the
thrusters 114a and 114b. Intermediate pulleys 113c and 113d are
disposed on positions near the pulleys 113a and 113b. Intermediate
pulleys 113e and 113f are disposed on positions nearer the
thrusters 114a and 114b to the intermediate pulleys 113c and 113d.
Further, intermediate pulleys 113g and 113h are disposed on
positions nearer to the thrusters 114a and 114b to the intermediate
pulleys 113e and 113f.
[0090] As shown in FIG. 8(a), the pulleys 113a and 113b on the side
of the motors 107a and 107b and the intermediate pulleys 113c and
113d are connected to each other by belts 112a and 112b. The
intermediate pulleys 113e and 113f and the intermediate pulleys
113g and 113h are connected to each other by belts 112c and 112d.
The intermediate pulleys 113g and 113h and the pulleys 113j and
113k on the side of the thrusters are connected to each other by
belts 112e and 112f.
[0091] As shown in FIG. 8(b), the maintenance/repair mechanism 108
includes a housing 115, an equipment 116 that maintains and repairs
the cylindrical structure 19, and a motor 117 that drives the
equipment 116 in a longitudinal direction of the cylindrical
structure 19. A gear 118a is connected to an output shaft of the
motor 117. Connected to the gear 118a is a ball screw 119 via a
gear 118b and a gear 118c. A nut 120 is engaged with the ball screw
119, and the nut 120 is connected to one end of a container case
122 for containing the equipment 116. Connected to the other end of
the container case 122 is a slide guide 121 that makes slidable the
container case 122 with respect to the housing 115. The
maintenance/repair mechanism 108 is removably mounted on the device
body 123.
[0092] As shown in FIG. 8(b), the equipment 116 of the
maintenance/repair mechanism 108 is formed of an ultrasonic
flaw-detecting probe, such as a phased-array UT probe, which can
ultrasonically detect a flaw such as a crack of the cylindrical
structure 19 without contacting the cylindrical structure 19.
[0093] In order to neutrally float the preventive
maintenance/repair device 100 so as to move the preventive
maintenance/repair device 100 in water by thrust force of the
thruster driving parts 106a and 106b, a buoyant member (not shown)
is located in one of the device body 123 and the maintenance/repair
mechanism 108.
[0094] As shown in FIGS. 7(a) and 7(b), arranged on an upper
surface of the device body 123 are pendant fittings 111a 111b to
which a rope and the like is fitted when the preventive
maintenance/repair device 100 is lowered from the upper part of the
reactor pressure vessel 1 in a hanging manner.
[0095] According to this embodiment, as shown in FIG. 8(a), when
the preventive maintenance/repair device 100 is moved in the water,
the motors 107a and 107b of the thruster driving parts 106a and
106b are driven. The rotations of the motors 107a and 107b are
transmitted to the intermediate pulleys 113c and 113d through the
pulleys 113a and 113b and the belts 112a and 112b. Then, the
rotations are transmitted to the intermediate pulleys 113g and 113h
through the intermediate pulleys 113e and 113f connected to the
intermediate pulleys 113c and 113d and through the belts 112c and
112d. The rotations are further transmitted to the pulleys 113j and
113k though the belts 112e and 112f connected to the intermediate
pulleys 113g and 113h. Thus, the rotations of the motors 107a and
the 107b are transmitted to the thrusters 114a and 114b, so that
the thrusters 114a and the 114b are rotated.
[0096] Since the buoyant member (not shown) is located in one of
the device body 123 and the maintenance/repair mechanism 108, the
preventive maintenance/repair device 100 can neutrally float.
[0097] Thus, the preventive maintenance/repair device 100 can be
moved in the water by the thrust force of the thruster driving
parts 106a and 106b. As a result, the preventive maintenance/repair
device 100 can be moved in the water, without the use of an access
device that attaches/detaches the preventive maintenance/repair
device 100 to/from the cylindrical structure 19.
[0098] As shown in FIGS. 7(a) and 7(b), the traveling wheel 101 of
the traveling and driving part 102 is in contact with the outer
circumferential surface of the cylindrical structure 19. In
addition, by driving the arm cylinders 109a and 109b of the holding
mechanisms 104a and 104b, the guide rollers 105a and 105b disposed
on the distal ends of the arms 103a and 103b are pressed onto the
outer circumferential surface of the cylindrical structure 19 via
the links 110a and 110b and the arms 103a and 103b. Therefore, the
preventive maintenance/repair device 100 can be held on the outer
circumferential surface of the cylindrical structure 19.
[0099] As shown in FIG. 8(b), when the equipment 116 of the
maintenance/repair mechanism 108 is moved in the longitudinal
direction of the cylindrical structure 19, the motor 117 of the
maintenance/repair mechanism 108 is driven. The equipment 116 is
slidably disposed in the longitudinal direction of the cylindrical
structure 19 with respect to the fixed housing 115 by the slide
guide 121. The rotational drive of the motor 117 is transmitted to
the ball screw 119 via the gears 118a, 118b, and 118c, and the
rotational motion of the ball screw 119 is converted into a
vertically linear motion by the nut 120. Thus, the equipment 116
connected to the nut 120 is slid in the longitudinal direction of
the cylindrical structure 19. Accordingly, the equipment 116 can be
precisely moved toward a target region of the cylindrical structure
19 in the longitudinal direction of the cylindrical structure
19.
[0100] The traveling and driving mechanism 108 can be easily
mounted on and removed from the device body 123. Thus, if the
maintenance/repair mechanism 108 is broken for some reason or
another, the whole preventive maintenance/repair device 100 is
drawn upward, and the broken maintenance/repair mechanism 108 can
be replaced with another normal maintenance/repair mechanism 108,
which has been prepared beforehand, for a short period of time.
[0101] As shown in FIGS. 7(a) and 7(b), when the preventive
maintenance/repair device 100 is circumferentially moved along the
outer circumferential surface of the cylindrical structure 19, the
motor (not shown) of the traveling and driving part 102 is driven
so that the traveling wheel 101 is driven in rotation. When the
preventive maintenance/repair device 100 is circumferentially moved
along the outer circumferential surface of the cylindrical
structure 19, the guide rollers 105a and 105b disposed on the
distal ends of the arms 103a and 103b of the holding mechanism 104a
and 104b are rotated in accordance with the movement of the
preventive maintenance/repair device 100. Also at this time, as
described above, the guide rollers 105a and the 105b are pressed
onto the outer circumferential surface of the cylindrical structure
19 by the arm cylinders 109a and 109b of the holding mechanisms
104a and 104b. Thus, the preventive maintenance/repair device 100
can be smoothly, circumferentially moved along the outer
circumferential surface of the cylindrical structure 19, while the
preventive maintenance/repair device 100 is being held on the outer
circumferential surface of the cylindrical structure 19.
Accordingly, the equipment 116 of the maintenance/repair mechanism
108 can be smoothly moved to a desired circumferential position
along the outer circumferential surface of the cylindrical
structure 19. As a result, the cylindrical structure 19 can be
maintained and repaired over all the circumferential surface
thereof by the equipment 116.
[0102] The traveling and driving part 102 can be easily mounted on
and removed from the device body 123. Thus, if the traveling and
driving part 102 is broken for some reason or another, the whole
preventive maintenance/repair device 100 is drawn upward, and the
broken traveling and driving part 102 can be replaced with another
normal traveling and driving part 102, which has been prepared
beforehand, for a short period of time.
[0103] When the equipment 116 of the maintenance/repair mechanism
108 shown in FIG. 8(b) is formed of an ultrasonic flaw-detecting
probe, a target region of the cylindrical structure 19 can be
ultrasonically detected. Thus, whether there is a crack or not in a
welding line of the cylindrical structure 19 can be checked. In
addition, various maintaining and repairing operations are possible
by using other equipments 116 that are similar to the equipments in
the first embodiment.
[0104] Due to the provision of the pendent fittings 111a and 111b
on the upper surface of the device body 123, the preventive
maintenance/repair device 100 can be lowered from the upper part of
the reactor pressure vessel 1 in a hanging manner, by connecting a
rope or the like to the pendent fittings 111a and 111b.
[0105] According to this embodiment, the preventive
maintenance/repair device 100 can be securely held on the outer
circumferential surface of the cylindrical structure 19 installed
in the reactor pressure vessel 1. In addition, the preventive
maintenance/repair device 100 can be circumferentially moved on the
outer circumferential surface of the cylindrical structure 19. In
addition, the preventive maintenance/repair device 100 can be moved
in water. Thus, the preventive maintenance/repair device 100 can be
precisely moved to a target region of the outer circumferential
surface of the cylindrical structure 19, so that the outer
circumferential surface of the cylindrical structure 19 can be
maintained and repaired.
* * * * *