Note: Descriptions are shown in the official language in which they were submitted.
CA 2766596 2017-03-07
Attorney Docket No. 027813-9027
FASTENER SHEARING TOOL
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority to U. S. Provisional Patent
Application No.
61/432,976, filed January 14, 2011.
BACKGROUND
[0002] The present invention relates to tooling for nuclear reactor
refurbishment operations,
for example, tooling for refurbishment operations of a CANDUTm-type nuclear
reactor.
[0003] More specifically, the invention relates to removal of feeder
components from the
primary heat transport system of a CANDUTNA-type nuclear reactor. The CANDUTM
("CANada
Deuterium Uranium") reactor is a pressurized heavy-water moderated, fission
reactor capable of
using fuels composed of natural uranium, other low-enrichment uranium,
recycled uranium,
mixed oxides, fissile and fertile actinides, and combinations thereof.
SUMMARY
[0004] In some embodiments, the invention provides a tool for separating a
feeder coupling
from an end-fitting of a nuclear reactor fuel channel by shearing one or more
feeder coupling
fasteners. A gripper has an inside surface and an outside surface. A portion
of the inside surface
is configured to engage a snout of the end fitting. A pusher is disposed about
the gripper. The
pusher has a nose portion for contact with the feeder coupling. An actuator
controllably acts
between the pusher and the gripper to drive the pusher into the feeder
coupling to shear the
feeder coupling fasteners.
[0005] Other embodiments, the invention provides a system for separating a
feeder coupling
from an end-fitting of a nuclear reactor fuel channel by shearing one or more
feeder coupling
fasteners. A hydraulic tool assembly includes a gripper having an inside
surface and an
outside surface. A portion of the inside surface is configured to engage a
snout of the end
fitting. A plunger is movably disposed within the inside surface of the
gripper. The plunger has
a first portion with a first outside diameter substantially conforming to an
inside diameter of the
end fitting, and a second portion having a second outside diameter
substantially greater than
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the inside diameter of the end fitting. The plunger defines a radial shoulder
between the first
portion and the second portion. The radial shoulder is configured to contact a
distal end of the
end fitting. A pusher is disposed about the gripper and the plunger. The
pusher has a nose
portion for engagement with the feeder coupling during shearing operations. A
hydraulic
cylinder acts between the pusher and the gripper to drive the pusher into the
feeder coupling to
shear the feeder coupling fasteners. The system further includes a hydraulic
supply, a user input
module, and a control module receiving user input signals from the user input
module, and
transmitting control signals to the hydraulic supply to controllably actuate
the hydraulic cylinder.
[0006] In other embodiments, the invention provides a method of separating
a feeder
coupling from an end-fitting of a nuclear reactor fuel channel. A gripper is
positioned into
engagement with a snout of the end fitting. A plunger is inserted into the end
fitting, such that a
first portion of the plunger with a first outside diameter substantially
conforms to an inside
diameter of the end fitting and a radial shoulder of the plunger contacts a
distal end of the end
fitting. A hydraulic fluid is controllably supplied to a hydraulic cylinder.
The hydraulic cylinder
acts upon the gripper and a pusher to cause relative motion therebetween. A
nose portion of the
pusher is engaged with the feeder coupling, thereby shearing a feeder coupling
fastener.
BRIEF DESCRIPTION OF THE DRAWINGS
100071 FIG. 1 is a perspective view of a reactor core of a nuclear reactor.
[0008] FIG. 2 is a cutaway view of a nuclear reactor fuel channel.
[0009] FIG. 3 is a front perspective view of a hydraulic tool assembly
(HTA) of a feeder
coupling disconnect tool.
[0010] FIG. 4 is a rear perspective view of the HTA of FIG. 3.
[0011] FIG. 5 is a front perspective view with a partial section of the
HTA.
[0012] FIG. 6 is a perspective view of a typical bolted connection of a
feeder to an end fitting
(EF).
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[0013] FIG. 7 is a cross-sectional view of the HTA, placed above an EF.
[0014] FIG. 8 is a cross-sectional view of the HTA of FIG. 7, lowered over
the EF.
[0015] FIG. 9 is a cross-sectional view of the HTA showing a plunger in an
advanced
position.
[0016] FIG. 10 is a cross-section view of the HTA with a push tube extended
into
interference with a feeder coupling.
[0017] FIG. 11 is a detailed view of a front portion of the HTA showing a
nosepiece,
wedges, and alignment pins, with both alignment pins in a retracted position.
[0018] FIG. 12 is a detailed view of the front portion of the HTA showing
the nosepiece,
wedges and alignment pins, with one pin extended.
[0019] FIG. 13 is a layout of a system control pendant.
[0020] FIG. 14 illustrates installation of a bolt retainer on a CANDUTm 6-
type EF.
100211 FIG. 15 is a perspective view of a nonCANDUTM 6 EF with a bolt
retention device
13 installed.
[0022] FIG. 16 is a section view of the EF and EF bushing of FIG. 14.
[0023] FIG. 17 is a perspective view of a square catch tray.
[0024] FIG. 18 is an image of the square catch tray installed in an array
of EF' s.
[0025] FIG. 19 is a perspective view of the square catch tray with support
arms.
[0026] FIG. 20 is an image of the square catch tray with support arms
installed in an array of
EFs.
[0027] FIG. 21 is a perspective view of a profiled catch tray 16.
[0028] FIG. 22 is an image of the profiled catch tray installed in an array
of EFs.
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[0029] FIG. 23 is a front perspective view of a powerpack skid.
[0030] FIG. 24 is a rear perspective view of the powerpack skid of FIG. 23.
[0031] FIG. 25 is a perspective view of an A-frame support.
[0032] FIG. 26 is an illustration of feeder coupling removal operations.
[0033] FIG. 27 is an alternative illustration of feeder coupling removal
operations.
[0034] FIG. 28 is a block diagram of the FCDT.
DETAILED DESCRIPTION
[0035] Before any embodiments of the invention are explained in detail, it
is to be
understood that the invention is not limited in its application to the details
of construction and the
arrangement of components set forth in the following description or
illustrated in the following
drawings. The invention is capable of other embodiments and of being practiced
or of being
carried out in various ways.
[0036] FIG. 1 is a perspective of a reactor core of a reactor 6. The
reactor core is typically
contained within a vault that is sealed with an air lock for radiation control
and shielding. A
generally cylindrical vessel, known as a calandria 10, contains a heavy-water
moderator. The
calandria 10 has an annular shell 14 and a tube sheet 18 at a first end 22 and
a second end 24.
The tube sheets 18 include a plurality of bores that accept a fuel channel
assembly 28. As shown
in FIG. 1, a number of fuel channel assemblies 28 pass through the tube sheets
18 of calandria 10
from the first end 22 to the second end 24.
[0037] FIG. 2 is a cut-away view of the fuel channel assembly 28. As
illustrated in FIG. 2,
each fuel channel assembly 28 is surrounded by a calandria tube ("CT") 32. The
CT 32 forms a
first boundary between the heavy water moderator of the calandria 10 and the
fuel bundles or
assemblies 40. The CTs 32 are positioned in the bores on the tube sheet 18. A
CT rolled joint
insert 34 within each bore is used to secure the CT 32 to the tube sheet 18.
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[0038] A pressure tube ("PT") 36 forms an inner wall of the fuel channel
assembly 28. The
PT 36 provides a conduit for reactor coolant and the fuel bundles or
assemblies 40. The PT 36,
for example, generally holds two or more fuel assemblies 40 and acts as a
conduit for reactor
coolant that passes through each fuel assembly 40. An annulus space 44 is
defined by a gap
between the PT 36 and the CT 32. The annulus space 44 is normally filled with
a circulating
gas, such as dry carbon dioxide, helium, nitrogen, air, or mixtures thereof
The annulus space 44
and gas are part of an annulus gas system. The annulus gas system has two
primary functions.
First, a gas boundary between the CT 32 and PT 36 provides thermal insulation
between hot
reactor coolant and fuel within the PTs 36 and the relatively cool CTs 32.
Second, the annulus
gas system provides an indication of a leaking CT 32 or PT 36 via the presence
of moisture,
deuterium, or both in the annulus gas.
[0039] An annulus spacer or garter spring 48 is disposed between the CT 32
and PT 36. The
annulus spacer 48 maintains the gap between the PT 36 and the corresponding CT
32, while
allowing the passage of the annulus gas through and around the annulus spacer
48. Maintaining
the gap helps ensure safe and efficient long-term operation of the reactor 6.
[0040] As also shown in FIG. 2, an end fitting (EF) 50 is attached around
the fuel channel
assembly 28 outside of the tube sheet 18 at each end 22, 24. At the front of
each end fitting 50 is
a closure plug 52. A feeder assembly 54 is coupled to each EF 50. The feeder
assemblies 54
feed reactor coolant into or remove reactor coolant from the PTs 36. In
particular, for a single
fuel channel assembly 28, the feeder assembly 54 on one end of the fuel
channel assembly 28
acts as an inlet feeder, and the feeder assembly 54 on the opposite end of the
fuel channel
assembly 28 acts as an outlet feeder. As shown in FIG. 6, the feeder
assemblies 54 are attached
to the end fitting 50 via a feeder coupling 56. The feeder coupling 56 is
fastened to the end
fitting 50 with a four feeder fasteners 57.
[0041] Referring back to FIG. 2, coolant from the inlet feeder flows along
a perimeter
channel of the end fitting 50 until it reaches a shield plug 58. The shield
plug 58 is contained
inside the end fitting 50 and provides radiation shielding. The shield plug 58
also includes a
number of openings that allow the coolant provided by the inlet feeder to
enter an end of a PT
36. A shield plug 58 located within the end fitting 50 at the other end of the
fuel channel
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assembly 28 includes similar openings that allow coolant passing through the
PT 36 to exit the
PT 36 and flow to the outlet feeder assembly 54 through a perimeter channel of
another end
fitting 50 at the opposite face of the reactor 6. As shown in FIG. 1, feeder
tubes 59 are
connected to the feeder assemblies 54 in order to carry coolant to or away
from the reactor 6.
[0042] Returning to FIG. 2, a positioning hardware assembly 60 and
bellows 62 are also
coupled to each end fitting 50. The bellows 62 allows the fuel channel
assemblies 28 to move
axially. The positioning hardware assemblies 60 are used to set an end of a
fuel channel
assembly 28 in either a locked or unlocked position. In a locked position, the
end of the fuel
channel assembly 28 is held stationary. In an unlocked position, the end of
the fuel channel
assembly 28 is allowed to move. A tool can be used with the positioning
hardware assemblies
60 to switch the position of a particular fuel channel assembly 28.
100431 The positioning hardware assemblies 60 are also coupled to an
end shield 64. The
end shields 64 provide additional radiation shielding. Positioned between the
tube sheet 18 and
the end shield 64 is a lattice sleeve or tube 65. The lattice tube 65 encases
the connection
between the end fitting 50 and the PT 36 containing the fuel assemblies 40.
Shielding ball
bearings 66 and cooling water surround the exterior the lattice tubes 65,
which provides
additional radiation shielding.
[0044] In a reactor, periodic refurbishment operations may include
retubing. Retubing is the
process of removing CTs, PTs, and associated feeder piping from the Calandria,
and replacing
them with new or refurbished components.
[0045] One portion of the retubing process includes disconnecting each
feeder assembly 54
from its corresponding end fitting EF 50. As previously mentioned, the feeder
54 is coupled to
the EF 50 at a feeder coupling 56 by multiple fasteners 57, as best
illustrated in FIG. 6. As
explained in greater detail below, rather than remove each fastener 57
individually, a Feeder
Coupling Disconnect Tool (FCDT) applies an axial force to the feeder coupling
56 to break the
bolts 57.
[0046] The FCDT is a system including a hydraulic tool assembly (HTA)
68 (FIGS. 3 and
4)), a hydraulic power pack 70 (FIGS. 23 and 24), an optional EF bushing 72
(FIG. 16), a set of
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bolt retention devices 74 (FIGS. 14-16), catch trays 76, 78 (FIGS. 17-22), and
an overhead
support mechanism such as an A-frame support 80 (FIG. 25).
[0047] Referring to FIGS. 14-16, the bolt retention device 74 is installed
over the feeder
coupling 56 on the target EF 50 to stop the broken bolt heads and other
hardware from ejecting.
Multiple bolt retention devices 74 are provided with each FCDT so that
uninterrupted tool cycles
can continue during the face series.
[0048] FIGS. 17-21 illustrate various catch trays. Referring to FIG. 17, a
square catch tray
76 is illustrated. Referring to FIG. 18, the square catch tray 76 can be
positioned between rows
of EFs 50. The square catch tray 76 is positioned under the EF 50 being worked
on to prevent
small reactor components from falling. Referring to FIG. 19, a pair of support
arms 82 may be
used in conjunction with the square catch tray 76. Referring to FIG. 20, the
support arms 82 are
used to support the square catch tray 76 where no EFs are available for
support below the target
EF.
[0049] Referring to FIG. 21 a profiled catch tray 78 is used when vertical
feeders are near the
target EF 50. As illustrated in FIG. 22, the profiled catch tray simply rests
on the EFs 50 below
the target EF 50.
[0050] As shown in FIG. 15, an EF 50 may have a helical thread-like
interface 83 for the
closure plug 52 (FIG. I), which creates difficulty in transmitting the extreme
loading generated
by the IITA 68 to the EF 50. To facilitate this, if required, the EF bushing
72 is inserted into the
EF SO before the I4TA 68 is installed. FIG. 16 illustrates an end-fitting
bushing 72 installed in an
EF 50. The end-fitting bushing 72 is only used for those reactors using a
helical groove closure
plug. For those reactors having EFs 50 without helical closure grooves, such
as are illustrated in
FIG. 14, no bushing 72 is used.
[0051] In some embodiments, the HTA 68 applies an axial force to the feeder
coupling 56 to
break the feeder fasteners 57. The HTA applies sufficient force to break 3/4"
and larger 7/9"
Inconel 718 bolts. The HTA 68 of the FCDT weighs approximately 1200 - 1300
lbs. In other
embodiments, the tool weighs approximately 1100 lbs. Referring to FIG. 3, the
HTA 68 is
roughly 12" in diameter and 62" long, with two support legs 84 and two handles
86.
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[0052] Referring to FIG. 7, the HTA includes a gripper 88, a pusher 90, a
plunger 92, and an
actuator, such as a hydraulic cylinder 94.
[0053] The gripper 88 includes a hollow body having an inside surface 98
and an outside
surface 102. The inside surface 98 has an inside diameter 104. A portion of
the inside surface
defines a semi-annular groove 106 configured to engage a snout 108 of the EF
50.
[0054] Referring to FIG. 8, the plunger 92 includes a substantially
cylindrical body having a
first portion 110 with a first diameter 112 substantially conforming to an
inside diameter of the
EF 50, and a second portion 114 having a second outside diameter 116
substantially greater than
the inside diameter of the EF 50. The second outside diameter 116
substantially conforms to the
inside diameter 104 of the gripper 88. The plunger further defines a radial
shoulder 118 between
the first portion 110 and the second portion 114. The radial shoulder 118 is
configured to contact
the snout 108 of the EF 50.
[0055] The plunger 92 is coupled to a plunger actuator assembly 120. In the
illustrated
embodiment, the plunger actuator assembly 120 includes a lead screw 122. The
lead screw 122
is rotatably coupled to the gripper 88 and drivingly coupled to the plunger
92. A handle 124,
also illustrated in FIGS. 3-4, is fixed to the lead screw 122 for user
actuation of the lead screw.
Rotation of the lead screw 122 causes the plunger 92 to advance or retract
along a plunger axis
126.
[0056] The pusher 90 includes a substantially cylindrical body 128 with an
extended nose
portion 130 for contact with the feeder coupling 56. The pusher 90 is disposed
about the gripper
88 and plunger 92. In the illustrated embodiment, the pusher is substantially
coaxial with the
gripper 88 and plunger 92 along the plunger axis 126. The pusher 90 may be
fabricated from
hardened tool steel. In some embodiments, an anti-friction coating may be
applied to all, or
portions of, the pusher 90.
[0057] RefeiTing to FIGS. 11 and 12, some embodiments of the pusher 90
include a nose
piece 132, and wedges 134 and 136. The nose piece 132 and wedges 134 and 136
are detachably
fastened to the pusher nose portion 130 so that they may be removed for
replacement or
inspection.
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[0058] FIGS. 11 and 12 further illustrate a first and second alignment pin
assemblies 138 and
140. Each alignment pin assembly 138 and 140 includes a pin member 142 and a
pin actuation
handle 144 coupled to the pin member 142. Each pin actuation handle 144
extends through a u-
shaped notch 146 defined in the pusher body 128. With the pin actuation handle
144 engaged to
a rear portion of the notch 146, as in FIG. 11, the alignment pin member 142
is retracted behind
the nose, nosepiece, and wedges. With the pin actuation handle 144 engage to a
forward portion
of the notch 146, as in FIG. 12, the pin member 142 extends beyond the nose
portion 130,
nosepiece 132, and wedges 134 and 136.
[0059] Referring to FIGS. 7-10, hydraulic cylinder 94 selectively drives
the pusher 90
relative to the gripper 88. In the illustrated embodiment, the hydraulic
cylinder 94 is a hollow-
piston, double-acting cylinder with a body 148 and a piston 150. The pusher 90
is fixedly
coupled to the body 148, while the gripper 88 is fixedly coupled to the piston
150. The hydraulic
cylinder 94 may be provided by EnerpacTM or another vendor. In other
embodiments, the
hydraulic cylinder 94 may be replaced or supplemented by another type of
actuator, including a
pneumatic piston, gear arrangement, lead screw or other mechanical or electro-
mechanical
actuating means.
[0060] Referring to FIGS. 23 and 24, the hydraulic cylinder 94 is actuated
by hydraulic fluid
received from the hydraulic power pack 70 of the FCDT. FIG. 28 is a block
diagram of the major
components of the hydraulic power pack 70. The hydraulic power pack 70
includes an electric
power supply 152, a control module 154, a hydraulic pump 156, and a control
valve 158. The
electric power supply 152 includes two circuits of 120V, one 15A and one 20A.
The hydraulic
power pack 70 may be a modified commercial unit with extra system monitoring
sensors added.
[0061] The control module 154 provides control signals to the control valve
158, which
controls the flow of hydraulic fluid to the hydraulic cylinder 94. A plunger
forward sensor 160,
coupled to the plunger 92, provides a control signal to the control module 154
related to a
position of the plunger 92 relative to the EF 50. A hydraulic cylinder
retracted sensor 162,
coupled to the hydraulic cylinder 94, provides a control signal to the control
module 154 related
to a retracted position of the hydraulic cylinder 94. A hydraulic cylinder
maximum stroke sensor
164 provides a control signal to the control module 154 related to a maximum
stroke position of
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the hydraulic cylinder 94. Each of the sensors 160, 162, and 164, may be, for
example, a
proximity sensor.
[0062] The control module 154 receives user inputs from a control pendent
166. FIG. 13
illustrates a configuration of the control pendent 166. The control pendent
includes a forward
button 168 and a reverse button 170. Pressing the forward button 168 causes
the hydraulic
cylinder 94 to advance until the maximum stroke sensor 164 indicates that the
hydraulic cylinder
94 has fully extended. Pressing the reverse button 170 causes the hydraulic
cylinder 94 to retract
until the retracted sensor 162 indicates the hydraulic cylinder 94 has fully
retracted.
[0063] The action of breaking the four bolts per connection is accomplished
through the
following steps. As shown in FIG. 7, the HTA 68 is first located over the
target EF 50. As
shown in FIG. 8, the HTA 68 is next placed on the EF 50, with the semi-annular
groove 106 of
the gripper 88 engaged to the snout 108. To securely fasten the HTA 68 to the
EF 50, the
plunger 92 is fully inserted in the EF 50 to strengthen the EF 50 and to lock
the HTA 68 onto the
EF 50. With the plunger 92 fully inserted into the EF 50, as indicated by the
plunger forward
sensor 160 (FIG. 28), the HTA 68 is substantially prevented from becoming
disconnected from
the EF 50.
[0064] With the gripper 88 engaged to the snout 108 and the plunger 92
inserted in the EF,
the HTA can still rotate about the plunger axis 126. This degree of freedom is
used in aligning
the nose portion 130 of the pusher 90 with the feeder coupling 56.
[0065] One alignment pin 142 is extended, as shown in FIG. 12, by moving
the alignment
pin handle 144 into a forward locked position. The HTA 68 is then rotated
about the plunger
axis 126, to position the alignment pin against one face of the feeder
coupling 56.
[0066] To start the HTA, the hydraulic cylinder 94 must be in its fully
retracted position, as
indicated by the hydraulic cylinder retracted sensor 162, and the plunger 92
must be fully seated
in the EF 50, as indicated by the plunger forward sensor 160. The plunger
forward sensor signal
satisfies two criteria. First, that the HTA 68 is locked on the EF 50 and
cannot be dislodged
partway through the cycle. Second, that the plunger 92 stiffens the EF
structure, allowing it to
bear the force being applied to break the feeder fasteners 57. If the plunger
92 were not present,
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the HTA 68 could pose a danger to the operator and the EF 50 could suffer
catastrophic damage.
It is desirable for the EF 50 to remain intact for subsequent refurbishment
operations.
[0067] Upon starting the HTA, an automatic cycle ensures that all four
feeder fasteners 57
will be sheared with one full stroke of the hydraulic cylinder 94. This action
is completed in two
stages. The HTA 68 initially applies forces off-center of the feeder coupling
56, causes two
fasteners in-line with a point of contact to break first. In this first phase
the feeder coupling 56
twists about the EF until it runs out of travel. When the first two feeder
fasteners 57 have broken
and the feeder coupling 56 is free to twist a bit more, the coupling now makes
contact with the
nose portion 130 at two points, and exerts all of the force on the two
remaining feeder fasteners
57. Once these last two bolts have broken the tool arrives at its maximum
stroke, as indicated by
the hydraulic cylinder maximum stroke sensor 164, a user is prompted to
reverse the hydraulic
cylinder 94 to return it to the starting position, as indicated by the
hydraulic cylinder retracted
sensor 162.
100681 The HTA 68 is extremely robust and does not require regular
maintenance except for
the nose piece 132 and wedges 134 and 136 which contact the feeder coupling
56. These
components may be checked periodically for damage and replaced if the contact
faces have
become damaged. In the event of a tool failure, the malfunctioning component
can be replaced
from spares provided with the FCDT system. Quick disconnects on sensor cables
and hydraulic
hoses provide for quick changeouts of the HTA 68, the hydraulic power pack 70
or both.
[0069] FIG. 25 is a perspective view of the A-frame support 80 for
supporting the HTA 68.
The A-frame 80 is equipped with a hoist 172. A pneumatic cylinder may that
isolates the hoist
172 from the excessive vertical loads that occur during operation of the HTA
68.
100701 Referring to FIGS. 26-27, the HTA 68 and A-frame support 80 are
located on a
retubing platform (RTP) 176 along with the operation pendants, while the
hydraulic power pack
70 are located on the vault floor connected by 75-foot (approximate)
cables/hoses.
100711 Thus, the invention provides, among other things, a tool for use in
the refurbishment
of nuclear reactors.
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