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Patent 2766591 Summary

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(12) Patent: (11) CA 2766591
(54) English Title: RETUBE PLATFORM FOR NUCLEAR REACTOR
(54) French Title: PLATE-FORME DE REMPLACEMENT DES TUBES D'UN REACTEUR NUCLEAIRE
Status: Granted
Bibliographic Data
(51) International Patent Classification (IPC):
  • G21C 21/00 (2006.01)
  • E04G 1/15 (2006.01)
  • G21C 17/017 (2006.01)
(72) Inventors :
  • BRIGGS, MICHAEL ALEXANDER (Canada)
  • MORIKAWA, DAVID (Canada)
  • GHANAVI, REZA (Canada)
(73) Owners :
  • ATOMIC ENERGY OF CANADA LIMITED (Canada)
(71) Applicants :
  • ATOMIC ENERGY OF CANADA LIMITED (Canada)
(74) Agent: NORTON ROSE FULBRIGHT CANADA LLP/S.E.N.C.R.L., S.R.L.
(74) Associate agent:
(45) Issued: 2018-03-27
(22) Filed Date: 2012-01-16
(41) Open to Public Inspection: 2012-07-15
Examination requested: 2016-10-20
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data:
Application No. Country/Territory Date
61/433,215 United States of America 2011-01-15

Abstracts

English Abstract

A retube platform system for installation in a reactor vault adjacent an end face of a CANDU reactor core during a retube process. The retube platform system includes a plurality of columns, a platform, and an elevator system. Each of the plurality of columns is supported on at least one floor surface of the vault. The platform includes a frame and a decking surface secured to the frame to provide a working surface for personnel and retube tooling. The platform includes a front end adjacent the end face and a rear end remote from the end face. The elevator system is provided between the plurality of columns and the platform and is configured to move the platform with a vertical travel substantially equal to a height of the end face.


French Abstract

Un système de plateforme de remplacement est destiné à une installation dans une voûte de réacteur adjacente à une face dextrémité dun cur de réacteur CANDU pendant un procédé de remplacement des tubes. Le système de plateforme de remplacement comprend une pluralité de colonnes, une plateforme et un système dascenseur. Chacune de la pluralité des colonnes est supportée sur au moins une surface de plancher de la voûte. La plateforme comprend un cadre et une surface de plateforme fixée au cadre pour fournir une surface de travail au personnel et à loutillage de remplacement de tube. La plateforme comprend une extrémité avant adjacente à la face dextrémité et une extrémité arrière éloignée de la face dextrémité. Le système dascenseur est présent entre la pluralité de colonnes et la plateforme et est configuré pour déplacer la plateforme selon un déplacement vertical substantiellement égal à une hauteur de la face dextrémité.

Claims

Note: Claims are shown in the official language in which they were submitted.


WHAT IS CLAIMED IS:
1. A retube platform system for installation in a reactor vault adjacent an
end face of
a CANDU.TM.-type nuclear reactor core during a retube process, the retube
platform
system comprising:
a plurality of columns supported on at least one floor surface of the vault;
a platform including a frame and a decking surface secured to the frame to
provide a working surface for personnel and retube tooling, the platform
including a front
end adjacent the end face and a rear end remote from the end face; and
an elevator system provided between the plurality of columns and the platform
and configured to move the platform with a vertical travel to provide access
to a full
height of the end face,
wherein a portion of the decking surface of the platform is movably coupled to
the
frame to form a selectively openable hatch therein.
2. The retube platform system of claim 1, further comprising a perimeter
railing
assembly provided around a majority portion of a perimeter of the platform,
the perimeter
railing assembly including a laterally-sliding opening and a plurality of
cables.
3. The retube platform system of claim 1, wherein the platform includes at
least one
vertically-telescoping side platform.
4. The retube platform system of claim 1, wherein the platform includes a
removable
front extension assembly.
5. The retube platform system of claim 1, wherein the elevator system
includes a
servo motor at a top end of each of the plurality of columns.
18

6. The retube platform system of claim 5, wherein the elevator system
includes a
ball-screw jack driven by each servo motor, and a controller configured to
actuate all of
the servo motors synchronously to move the platform vertically.
7. The retube platform system of claim 1, further comprising a flexible
cable track
for housing a plurality of electrical cables at the rear end of the platform.
8. The retube platform system of claim 1, further comprising at least one
linear
bearing rail provided on the decking surface.
9. The retube platform system of claim 8, wherein the at least one linear
bearing rail
includes two linear bearing rails spanning substantially across a width of the
platform.
10. The retube platform system of claim 8, further comprising at least one
rack gear
positioned adjacent the at least one linear bearing rail.
11. The retube platform system of claim 1, further comprising at least one
radiation
shielding wall forming a shielded walk-off area remote from the front end of
the
platform.
12. The retube platform system of claim 1, wherein the plurality of columns
are also
braced to at least one adjacent vault wall.
13. The retube platform system of claim 1, wherein a servo motor is coupled
to the
portion of the decking surface and operable to open and close the hatch.
14. The retube platform of claim 13, wherein the portion of the decking
surface is one
of a plurality of portions of the decking surface forming a plurality of
hatches, each of the
plurality of hatches being independently openable and closable with a
corresponding
servo motor.
19

15. A method of using a retube platform system in a reactor vault to access
and
service an end face of a CANDU.TM.-type nuclear reactor core including a
plurality of fuel
channels arranged in a grid, the method comprising:
providing a plurality of columns supported on at least one floor surface of
the
vault;
providing a platform including a frame and a decking surface secured to the
frame;
coupling the platform to the plurality of columns with an elevator system;
operating the elevator system to move the platform with a vertical travel to
provide access to a full height of the end face to provide access for
personnel and retube
tooling to each of the plurality of fuel channels during a retube process; and
opening a hatch to provide access through the decking surface.
16. The method of claim 15, further comprising providing the elevator
system with a
plurality of servo motors, a plurality of ball-screw jacks, and a controller
coupled to the
plurality of servo motors, and wherein operating the elevator system includes
synchronously actuating the plurality of servo motors with the controller.
17. The method of claim 15, wherein opening the hatch includes driving a
portion of
the decking surface to drop below and slide under an adjacent portion of the
decking
surface.
18. The method of claim 15, wherein opening the hatch includes pivoting a
hinged
portion of the decking surface downwardly.

Description

Note: Descriptions are shown in the official language in which they were submitted.


CA 2766591 2017-02-28
Attorney Docket No. 027813-9045-CA
RETUBE PLATFORM FOR NUCLEAR REACTOR
CROSS-REFERENCE TO RELATED APPLICATIONS
100011 This application claims priority to U.S. Provisional Patent
Application No.
61/433,215, filed January 15, 2011.
BACKGROUND
[0002] The present invention relates to nuclear reactors. More
particularly, the invention
relates to systems used in maintenance or refurbishment (e.g., a full retube)
of a nuclear reactor.
SUMMARY
[0003] In some embodiments, the invention provides a retube platform system
for
installation in a reactor vault adjacent an end face (reactor face) of a
CANDUTM reactor core
during a retube process. The retube platform system includes a plurality of
columns, a platform,
and an elevator system. Each of the plurality of columns is supported on at
least one floor
surface of the vault. The platform includes a frame and a decking surface
secured to the frame to
provide a working surface for personnel and retube tooling. The platform
includes a front end
adjacent the end face and a rear end remote from the end face. The elevator
system is provided
between the plurality of columns and the platform and is configured to move
the platform with a
vertical travel substantially equal to a height of the end face.
[0004] The invention also provides a method of using a retube platform
system in a reactor
vault to access and service an end face of a CANDUTM reactor core including a
plurality of fuel
channels arranged in a grid. A plurality of columns is provided, each of the
plurality of columns
being supported on at least one floor surface of the vault. A platform is
provided including a
frame and a decking surface secured to the frame. The platform is coupled to
the plurality of
columns with an elevator system. The elevator system is operated to move the
platform with a
vertical travel substantially equal to a height of the end face to provide
access for personnel and
retube tooling to each of the plurality of fuel channels during a retube
process.
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CA 02766591 2012-01-16
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Attorney Docket No. 027813-9045-CA
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] Fig. 1 is a perspective view of a reactor core.
[0006] Fig. 2 is a cut-away view of a fuel channel assembly of the
reactor core of Fig. 1.
[0007] Fig. 3 is a perspective view of a retube platform system installed
in a vault adjacent
the reactor core.
100081 Fig. 4 is a plan view of the retube platform system.
[0009] Fig. 5 is a side elevation of the retube platform system
illustrating the vertical stroke.
[0010] Fig. 6A is an assembly view of the retube platform system in a
first configuration
with perimeter side rails installed.
[0011] Fig. 6B is an assembly view of the retube platform system in a
second configuration
with inboard extensions installed.
[0012] Fig. 7A is a detail perspective view of a cable handrail system
that may be installed at
the front or the rear of the platform.
[0013] Fig. 7B is a perspective view of the retube platform system
illustrating a
configuration for a cable handrail system including a single traveling opening
at the rear side of
the platform.
[0014] Fig. 7C is a perspective view of the retube platform system
illustrating a
configuration for a cable handrail system including two traveling openings at
the rear side of the
platform.
[0015] Fig. 8A is a perspective view of a detachable front extension
assembly.
[0016] Figs. 8B and 8C are exploded assembly views of the two ends of the
detachable front
extension assembly of Fig. 8A.
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CA 02766591 2012-01-16
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Attorney Docket No. 027813-9045-CA
[0017] Fig. 9 is a plan view of a retube platform system of an
alternate construction,
illustrating exemplary lateral braces and alternate walk-off platforms.
[0018] Fig. 10 is an exploded assembly view of a first hatch in the
decking surface.
[0019] Fig. 11 is a perspective view of a second hatch in the
decking surface.
[0020] Fig. 12 is a perspective view showing front pylons installed
for the retube platform
system.
[0021] Fig. 13 is perspective view showing the front pylons with an
elevator fork in place.
[0022] Fig. 14 is a perspective view of the rear column and side-
beam installed.
[0023] Fig. 15 is a perspective view of a front structural assembly
of the retube platform
installed.
[0024] Fig. 16 is a perspective view of a middle structural assembly
of the retube platform
installed.
[0025] Fig. 17 is a perspective view of a rear beam of the retube
platform installed.
[0026] Fig. 18 is a perspective view of the retube platform assembly
with decking, handrails,
and a cable track installed.
[0027] Fig. 19 is a detail perspective view of a drive mechanism for
an elevator system of the
retube platform system.
DETAILED DESCRIPTION
[0028] 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.
3

CA 2766591 2017-02-28
Attorney Docket No. 027813-9045-CA
[0029] FIG. 1 is a perspective of a reactor core of a CANDUTm-type 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. The fuel
channel assemblies
28 are generally arranged in a horizontal and vertical grid on the end faces
of the reactor
core. Upper feeder tubes and lower feeder tubes 59 communicate with the fuel
channel
assemblies 28 to provide heavy-water to the fuel channel assemblies 28 during
operation of the
reactor.
[0030] 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.
[0031] 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.
[0032] 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
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CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
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.
[0033] As also shown in FIG. 2, an end fitting 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. Each end fitting 50 also includes a feeder assembly 54. 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. 2, the feeder
assemblies 54 can be
attached to the end fitting 50 using a coupling assembly 56 including a number
of screws,
washers, seals, and/or other types of connectors.
[0034] Coolant from the inlet feeder assembly 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 assembly 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
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 that carry coolant to or away from the reactor 6.
[0035] 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.
[0036] 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

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
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.
[0037] During a retube of the reactor 6, many of the major components of
the reactor core
are removed and replaced. Other components are inspected and/or repaired. For
example, all of
the fuel channel end fittings 50 are removed, all of the calandria tube
inserts 34 are removed, and
then the calandria tubes 32, the pressure tubes 36, and the associated annulus
spacers 48 (e.g.,
garter springs) are removed. In order to accommodate tooling and materials
used adjacent each
end face of the reactor core for at least these processes during a retube, a
retube platform system
100 is provided adjacent each end of the reactor core. One exemplary retube
platform system
100 is shown in Fig. 3, with the understanding that a substantially similar
retube platform system
can be provided in the vault on the opposite end of the reactor core.
Therefore, it will be
understood that the below description relates to the illustrated retube
platform assembly 100, but
multiple retube platform assemblies 100 would typically be provided to enable
servicing both
end faces of the reactor core simultaneously.
[0038] The retube platform system 100 is a stand-alone elevating platform
that provides
access to the reactor face for retube work. The retube platform system 100
includes a plurality of
columns 104 (e.g., four vertical columns), a platform 106 movably supported by
the columns
104, and an elevator system 108 for moving the platform 106 relative to the
columns 104. The
platform 106 includes a structural (e.g., steel) frame 110 and a decking
surface 112 coupled to
the frame 110. The platform 106 is sized (spatially and structurally) to
accommodate all of the
required tooling for removal, inspection, and installation series, including
heavy shielded flasks.
The platform 106 can have a plan view width W at least as wide as the
calandria 10 (e.g., about
22 feet) and a plan view length L measured perpendicular to the width W. The
platform 106 can
provide a working surface of about 500 square feet or more (e.g., the width W
can be about 29-
31 feet, and the length L can be about 17-24 feet). The platform 106 provides
a working surface
nearly filling the plan view area that the fueling machine and gantry normally
occupies. To
maximize working space, the platform 106 provides small clearances with
respect to surrounding
structures, including the underside when at the lowest elevation. The platform
106 can be
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CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
movable via the elevator system 108 to have a vertical stroke V (Fig. 5) that
is at least equal to
the height of the calandria 10 (e.g., about 22 feet), so that all of the fuel
channel assemblies 28
across the entire reactor end face are accessible from the platform 106. In
the illustrated
construction, the vertical stroke V is about 27 feet, or about 5 feet more
than the height of the
calandria 10. The elevator system 108 can position the platform 106 at any
desired height within
the vertical stroke V. Although the retube platform system 100 may be
configured to lower the
platform 106 into a pit or recess in the vault floor as illustrated, this is
dependent upon the vault
design at a particular reactor site and is not a necessary feature of the
invention.
[0039] The platform 106 provides a precision tooling base, as well as a
personnel work
platform onto which most of the tooling required for reactor disassembly and
reassembly may be
mounted. The accuracy of positioning of the tooling with respect to reactor
fuel channels is
achieved by providing the platform 106 with high relative rigidity and
stability. The retube
platform system 100 also serves as the primary elevating device for movement
of the heavy
shielded flasks from a lower elevation (e.g., vault floor) to the target
lattice site. In some
applications, the use of the retube platform system 100 provides a more
efficient method of
vertical movement than individually craning each of the large flasks down to a
lower elevation.
[0040] To support the platform 106, the columns 104 may be installed on
either side of
existing reactor area bridge columns 116 (e.g., four columns 104 for
positioning adjacent
corresponding corners of the platform 106). As described in further detail
below, a portion of the
elevator system 108 (e.g., a shaft 120 of a ball-screw jack) can be coupled to
each column 104 in
some constructions. Each ball-screw shaft 120 can be driven by a servo motor
124, which can be
coupled to an upper end of the corresponding column 104. Movement of the
platform 106
relative to the columns 104 by the servo motors 124 can provide at least
"coarse" vertical
positioning of the retube tooling to the target lattice site. In addition to
the columns 104, which
bear vertical loads, lateral braces 128 can be provided to bear lateral loads,
including seismic and
operational loads. Lateral brace configuration will depend upon vault design
at a particular
reactor site, but one example is shown in Fig. 9. Each lateral brace 128 can
couple one of the
columns 104 to the existing reactor area bridge columns 116 and/or the
surrounding structural
steel in the vault walls.
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CA 02766591 2012-01-16
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100411 As shown in Figs. 3, 4, 6A, and 6B, the platform 106 can include at
least one linear
bearing rail 130A, 130B. The illustrated platform 106 is provided with two
linear bearing rails
130A, 130B spaced in the length L direction and each spanning the width W of
the platform 106.
The first or inboard linear bearing rail 130A is provided at the inboard
(reactor-facing) edge of
the platform 106. The second or outboard linear bearing rail 130B is provided
on the outboard
portion of the platform 106, and may optionally be provided at the outboard
edge. The linear
bearing rails 130A, 130B are configured to slidably mount retubing equipment
to the platform
106. Such equipment can include, but is not limited to heavy work tables HWT
as shown in
Figs. 7B, 7C, and 9. A rack gear 131 can be provided adjacent each linear
bearing rail 130A,
130B or integrated therein to facilitate driving bearing-mounted equipment
across the platform
106. Although the teeth of the rack gear 131 are not necessarily visible in
the drawings due to
the resolution, it should be understood that each rack gear 131 provides a
straight, flat gear with
evenly spaced teeth provided along the length. The number of teeth per inch
can be 1 or more.
The rack gears 131 cooperate with pinion gears and drives provided on
tools/equipment such as
tables to allow controlled lateral movement of the tools/equipment along the
platform 106.
[0042] A cable management assembly 132 is used to provide electrical and
controls services
to all electrical devices used on the platform 106, including work tables and
tools. The cable
management assembly 132 can be a flexible cable track configured to
automatically collapse and
expand (e.g., fold and unfold) as necessary as the platform 106 travels up and
down. System
geometry is optimized to eliminate the floor gaps normally associated with
cable management
systems.
100431 With reference to Figs. 3-6A, handrails 136 can be provided at any
or all portions of
the perimeter of the platform 106. The handrails 136 can be removable and
reconfigurable as
desired, with little or no hardware required for installation and removal of
handrail sections. For
example, Fig. 3 illustrates handrails 136 enclosing the entire perimeter
except for two openings
138 at the lateral sides. These openings 138 can be used for ingress/egress of
workers to and
from the platform 106 (e.g., via movable staircases, fixed ladders, portable
lifts or other means).
As shown in Figs. 4-6A, each of these openings 138 can provide access to a
side extension walk-
off area 140 extending from the side of the platform 106. The walk-off area
140 can be
selectively enclosed with one or more handrails (metal or cable). The walk-off
area 140 can be
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CA 2766591 2017-02-28
Attorney Docket No. 027813-9045-CA
utilized as a shielded area at the working level, useful for workers to
minimize radiation dosage
during brief "standby" periods when they are not directly engaged in work on
the platform 106.
For this purpose, at least one radiation shielding plate 142 can be provided
at the reactor-facing
side of the walk-off area 140. Furthermore, one or more seats may be provided
in the walk-off
area 140. Also, as shown in Fig. 6A, the walk-off areas 140 can be
telescopically coupled to the
platform 106 (e.g., to allow the platform 106 to drop into a floor recess, if
provided).
[0044] Fig. 7A illustrates an alternate means of enclosing the perimeter of
the platform 106
or a portion thereof. Instead of metal handrails 136, a cable handrail system
136' is provided
with a traveling (e.g., laterally-sliding) opening 146. The traveling opening
146 is movable
along the perimeter of the platform 106, and can be positioned where retube
tooling will pass
through. Cables 148 of the handrail system 136' are coupled with the traveling
opening 146 on
one or both sides to move with the opening 146 so that the clearance necessary
for ingress/egress
of tooling is provided while keeping constraints in place everywhere else to
maintain worker
protection. Doors 150 for worker ingress/egress can optionally be provided
adjacent the
traveling opening 146.
[0045] As shown in Fig. 6B, the working surface of the platform 106 can
selectively be
extended on the inboard or front side (toward the reactor 6) via a front
extension assembly 154.
For example, the front extension assembly 154 may be installed on the platform
106 after
removal of end fittings to provide direct personnel access to the reactor
face. The front extension
assembly 154 includes one or more panels 156 and underlying structural beams
158 quickly and
non-permanently attachable to and removable from the platform 106 (e.g.,
without bolted joints).
The front extension assembly 154 is designed so that plant interferences, such
as end shield
cooling piping, are avoided and to provide a complete operating envelope from
top to bottom of
the reactor 6.
[0046] Figs. 7A-11 illustrate detailed features of the retube platform
system 100, which are
illustrated in conjunction with an alternate platform 106'. The platform 106'
can be modified for
a CANDUTm-6 type reactor. The platform 106' has a different aspect ratio of
length L' to width
W' compared to the platform 106. However, it should be understood that minor
feature
alterations, which may be due to reactor site-specific conditions, do not
significantly alter the
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CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
scope of the invention, and unless explicitly prohibited, features shown in
conjunction with one
of the platforms 106, 106' are applicable to the other. Features of the
alternate platform 106'
which are similar to features already described with respect to the platform
106 are amended
with(').
[0047] The platform 106' includes alternate walk-off areas or platforms
140'. The walk-off
areas 140' are located at the lateral sides of the platform 106'and each is
provided with two seats
141. The seats 141 may fold to a stowage position when not in use. Similar to
the walk-off
areas 140 discussed above, each of the walk-off areas 140' can be shielded to
reduce radiation
dose for workers on the platform 106' that are not directly engaged in a work
task.
[0048] The platform 106' includes a front extension assembly 154', which is
not attached in
Figs. 7B and 7C, but is attached in Fig. 9. Figs. 8A-8C illustrate the front
extension assembly
154' in further detail. The front extension assembly 154' includes a plurality
of panels 156' and
underlying structural beams 158'. In the illustrated construction, there are
six panels 156', each
of which is constructed of three sub-panels, but the exact configuration can
vary to include more
or less panels. Removable metal handrails 136' are provided for attachment to
a central section
and both side end sections of the front extension assembly 154'. Open working
spaces for
accessing the reactor 6 are provided between the handrails 136' at the central
and end sections.
The opposing ends of each panel 156' include coupling structures 162 for
coupling the panels
156' to the underlying structural beams 158'. In the illustrated construction,
the coupling
structures 162 are passive couplings, such as open concave-shaped brackets
configured to engage
an upper portion of a tubular member of the underlying structural beams 158'.
The facing
coupling structures 162 of adjacent panels 156' can engage a common member of
the underlying
structural beams 158 in an inter-woven relationship as best shown in Figs. 8B
and 8C to inhibit
lateral movement of the panels 156'. The panels 156' are held vertically in
place by gravity.
Thus, no bolted joints are required to couple the panels 156' to the
underlying structural beams
158'. Similarly, no bolted joints are required to couple the underlying
structural beams 158' to
the platform 106'. The platform 106' can be provided with receiver brackets
166 pre-installed
(e.g., bolted to the structural steel frame 110'¨Figs. 10-11). Each receiver
bracket 166 defines a
vertical channel 168 configured to vertically receive a corresponding tab or
tenon 172 of the
underlying structural beams 158'. The vertical channels 168 and the
corresponding tabs 172 are

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
formed with slanted walls to form a dove-tail joint that prevents lateral
movement when joined.
A stop 174 is provided at the bottom of each vertical channel 168 to limit the
vertical travel of
the tabs 172 and maintain the tabs 172 within the channels 168 by gravity.
[0049] The platform 106' includes at least one selectively openable hatch
176 in the decking
surface 112'. In the illustrated construction, three hatches 176 are provided,
including a pair of
opposed side hatches 176A, 176B and a middle hatch 176C. The hatches 176 are
illustrated in
Figs. 7B and 7C by the lack of any decking surface 112'. However, the decking
surface 112'
does extend over each of the hatches 176. One or more hatch panels 180 are
movably coupled to
the structural steel frame 110' in the area of each hatch 176. The first and
second hatches 176A,
176B are similar in structure, and each is formed by a pair of hinged (i.e.,
pivoting) hatch panels
180A, 180B. This construction is illustrated in further detail in Fig. 10,
with respect to the hatch
176A (with the understanding that the hatch 176B is substantially similar). A
plurality of hinges
182 couple opposite outside edges of each of the hatch panels 180 to the
structural steel frame
110'. The hinges 182 are configured to allow each of the hatch panels 180A to
swing down from
the adjacent decking surface 112' to open the hatch 176A. The opening and
closing of the hatch
panels 180A is controlled via a single servo motor 184 coupled to a plurality
of cam carriages
186 movable along the ends of the hatch panels 180A (i.e., the two
perpendicular ends adjacent
the hinged edge). Each end of each hatch panel 180A includes a downwardly-
facing cam surface
188 engaged with at least one cam follower 190 (e.g., roller) of a
corresponding one of the cam
carriages 186.
[0050] When the cam carriages 186 are positioned toward the free edges of
the hatch panels
180A, the cam roller(s) 190 engage the extended portion of the cam surfaces
188 to support the
hatch panels 180A in the horizontal orientation. When the cam carriages 186
are moved toward
the hinged edges of the hatch panels 180A, the cam surfaces 188 are shaped to
allow the hatch
panels 180A to gradually pivot downwardly to open the hatch 176A. The two cam
carriages 186
at each end of the hatch 176A are coupled to oppositely-threaded portions
192A, 192B of a
common ball screw shaft so that rotation of the ball screw shafts at each end
of the hatch causes
both hatch panels 180A to open/close simultaneously. The ball screw shafts at
the opposing ends
of the hatch 176A are rotated simultaneously by the servo motor 184 through a
primary 90-
degree gearbox 194, two oppositely-extending transmission shafts 196, two
secondary 90-degree
11

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
gearboxes 198, and associated couplings (at least one of the couplings 200 can
be an adjustable
coupling to adjust and ensure precise simultaneous opening and closing of the
hatch panels
180A). The cam carriages 186 are coupled in pairs for each hatch panel 180A by
connecting
beams 202 that span each hatch panel 180A. The side hatches 176A, 176B can be
used to raise
and lower shielded shuttle flasks (for shielded removal of end fittings) to
and from the platform
106' during the retube process.
[0051] The construction of the middle hatch 176C is illustrated in detail
in Fig. 11. The
hatch panel 180C forming the middle hatch 176C is coupled to the structural
steel frame 110' via
a linkage 206 (which can include a plurality of links and pivots not shown) to
be movable
vertically downward from the decking surface 112' and to slide horizontally
underneath an
adjacent section of the decking (removed from Fig. 11 for clarity). Side edges
of the hatch panel
180C are engaged with a plurality of guide slots 208 provided in side plates
210 secured to the
structural steel frame 110'. A base of the linkage 206 is coupled to a
carriage 212 movable along
a ball screw 214 driven by a servo motor 216 that is secured to the structural
steel frame 110'.
As the ball screw 214 is rotated to draw the carriage 212 to the left in Fig.
11, the guide slots 208
force the hatch panel 180C to be drawn down below the decking surface 112' (as
enabled by the
linkage 206) and slide under an adjacent deck panel. When operated in the
reverse direction, the
hatch panel 180C is driven laterally toward the closed position of Fig. 11,
and just before
reaching the maximum lateral stroke, is forced upward by the guide slots 208
to assume the
closed position, which is in-line with the remaining decking surface 112'. The
middle hatch
176C can be used to raise and lower shielded flasks to and from a volume
reduction machine
used on the platform 106' during the retube process. In other constructions,
volume reduction
may take place off of the platform 106, 106', and the middle hatch 176C can be
used for raising
whole portions of the components removed from the reactor, new components for
attachment to
the reactor, shielded containers, tooling, equipment, etc.
[0052] Referring again to Figs. 3-6A and also to Fig. 19, the elevator
system 108 includes
separate, commonly-controlled elevator subsystems (e.g., ball-screw jacks)
positioned at each
column 104 in the illustrated construction. Each ball-screw jack includes one
of the vertically-
oriented ball-screw shafts 120, the corresponding servo motor 124 and
transmission, and a
carriage 232 secured to the platform 106, 106' as described further below. The
ball-screw shafts
12

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
120 are secured at the inboard (platform-facing) side of each column 104 in a
rotatable manner
(e.g., with one or more bearings). The servo motor 124, or other suitable
drive, is coupled to the
ball-screw shaft 120 through a 90-degree gearbox 220 (Fig. 19), which can be
secured to the top
of the corresponding column 104. The gearbox 220 is provided with dual input
shaft portions
222A, 222B, and the output of the gearbox 220 is coupled to the ball-screw
shaft 120. A first
one of the input shaft portions 222A is coupled to the servo motor 124 to
receive driving input
force from the servo motor 124. The servo motor 124 has an integrated encoder
and internal
brake. The second one of the input shaft portions 222B is coupled to an
external brake 224,
which serves as a redundant back-up braking system to the brake internal to
the servo motor 124.
A mechanical release lever 226 can be provided to manually release the
external brake 224 after
actuated, or alternately, the external brake 224 can be electrically released.
A redundant
confirmation encoder 228 is also provided on the shaft adjacent the external
brake 224. The
elevator system 108 and its mounting to the columns 104 are designed so that
the position of the
servo motor 124 and the external brake 224 with respect to the dual input
shaft portions 222A,
222B can be simply interchangeable to suit the desired orientation at each
column 104. The
platform 106, 106' is coupled to the elevator system 108 with an elevator
block or carriage 232
adjacent each column 104. Each carriage 232 is engaged with the corresponding
ball-screw shaft
120 to travel vertically when the ball-screw shaft 120 is rotated. Each
carriage 232 is secured to
the platform 106, 106' (e.g., the structural steel frame 110, 110' thereof)
with a corresponding
attachment plate 234. The attachment plates 234 may be of various shapes and
sizes to
accommodate the relative orientation between the platform 106, 106' and the
bases of the
columns 104. For example, in at least one of the illustrated constructions,
the attachment plates
234 at the outboard side of the platform 106 are significantly longer than the
attachment plates
234 at the inboard side of the platform 106 since the columns 104 at the
outboard side of the
platform 106 do not extend down into the vault floor pit like the columns 104
at the inboard side
of the platform 106.
[0053] All of the servo motors 124 of the elevator system 108 are coupled
to a common
controller so that the servo motors 124 can be actuated to move synchronously.
The encoders
internal to each servo motor 124 provide position feedback to the controller,
and the position is
further confirmed by the external encoders 228 adjacent each external brake
224. The controller
13

CA 02766591 2012-01-16
,
,
Attorney Docket No. 027813-9045-CA
can be configured to utilize the position feedback to ensure that all four
corners of the platform
106, 106' are kept within a predetermined absolute height tolerance range
(e.g., 0.25 inches).
The retube platform system 100 can be interlocked to prevent operation when
the predetermined
absolute height tolerance range is exceeded for any reason.
100541 The retube platform system 100 is designed to ease
installation and assembly as much
as possible, considering the space restrictions in the vaults. Precision
fabrication, modularization
and pre-assembly are used to ensure an efficient set-up time on critical path.
For example,
precision machining of connections results in less time to line up and adjust
in the field during
actual assembly, where time is critical and delays are costly. Pre-assembling
the retube platform
system 100 into large modules, considering the maximum size constraints of the
reactor building,
will also reduce assembly time. By designing and fabricating in this way, the
retube platform
system 100 requires a minimal number of individual components that can be
assembled in-situ
with a minimal number of steps, fasteners, and alignment time.
[0055] The retube platform system 100 is useful in various
configurations, as discussed in
some amount of detail above (e.g., handrail configurations, front and side
extensions, etc.). In
addition to the various configurations described above, the retube platform
106, 106' can be used
by itself, supported by the vault floor at or near floor level, with none (or
fewer than all four) of
the columns 104 installed. For example, the platform 106, 106' can be used as
a simple working
floor during feeder cabinet removal, feeder platform installation, and feeder
installation.
[0056] Of course, when the columns 104 and the elevator system 108
are installed, the
platform system 100 assumes another configuration in which the platform 106,
106' is made
fully operational. The retube platform system 100 can be provided in this
operational
configuration for feeder removal, the reactor components removal series (front
extensions
installed after end fitting removal), and the reactor components installation
series.
[0057] The installation process of the retube platform system 100
is described below.
Components of the retube platform system 100, including the columns 104, the
platform 106,
and the components of the elevator system 108 are transferred into the
respective reactor vaults
using plant crane facilities with custom lifting beams, forklifts, dollies,
and rigging. Components
14

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
are positioned using the reactor area crane, as well as portable hydraulic
cylinders and other
alignment and set-up tooling as required.
[0058] In some constructions, the following installation and removal
sequences are used.
Sole plate locations are surveyed before drilling cores and installing
adhesive anchors and grout
sole plates (precision placement is required to aid installation down stream
in the process). Front
pylons 240A, 240B are then installed (e.g., using rigging from reactor area
crane girders, with
the crane parked in the forward-most position) as shown in Fig. 12. The pylon
240A is a sub-
frame for supporting one of the front columns and pylon B is a temporary
support for one of the
platform front deck corners. An elevator fork 242 is positioned on top of the
pylons 240A,
240B in position for connection with the platform frame 110. The fork 242 is
part of the elevator
mechanism which connects the comers of the platform 106 to the columns 104 and
allows for
vertical translation of the platform 106. The carriage 232 which is installed
on the column 104 is
moved vertically up/down by means of the ball-screw and column drive system,
an the fork 242
is attached to the comer of the platform 106. A yoke/suspension links transfer
vertical loads
from the platform 106 to the column 104. Lateral forces are selectively
(depending on each
particular corner of the platform 106) transmitted from the platform 106 to
the columns 104 via
an eccentric pin and "buttons" incorporated into the vertical surfaces of the
elevator fork 242 and
the carriage 232.
[0059] The rear or outboard columns 104 are then installed. After the rear
columns 104 are
installed, a side beam 244 is installed between the platform foot 242 and the
rear column 104
with the ball-screw shaft 120, the carriage 232, and the attachment plate 234
on each side (using
reactor area crane and spreader bars) (one beam shown in Fig. 14). Once the
side beams 244 are
in place, the front section 246 of the platform's structural steel frame 110
can be installed (Fig.
15), followed by the middle section 248 (Fig. 16), and the rear beam 250 (Fig.
17), using the
reactor area crane and spreader bars. After the structural steel frame 110 is
completely
assembled, the decking 112, the handrails 136, and the walk-off areas 140 are
installed (Fig. 18).
The linear bearing rails 130A, 130B and gear racks 131 which support and guide
work tables and
tooling may either be integral to the structural steel frame 110, 110' (e.g.,
integral with the front
section 246 and the rear beam 250) or installed at the vault assembly stage.
Finally, the cable
management system 132 is installed at the rear of the platform 106 (Fig. 18).

CA 02766591 2012-01-16
Attorney Docket No. 027813-9045-CA
[0060] At this stage of assembly, the retube platform system 100 can be
utilized as a simple
working floor as discussed above, and work requiring this configuration (e.g.,
see above
examples) can be conducted. Once this work is completed, the front columns 104
are installed
and connected to the platform 106 (with the associated components of the
elevator system 108)
as shown in Fig. 3. Then the appropriate column lateral braces can be coupled
to reactor area
bridge columns 116 and/or surrounding structural steel on the vault walls. The
retube platform
system 100 is then commissioned (although some commissioning may be conducted
previously)
and made functional as a vertically movable platform that can span the entire
height of the
calandria 10. Work table(s) and the cable handrail system 136' of Fig. 7A can
then be installed.
Later, after the end fittings are removed, the front extension assembly 154,
154' can be installed
to provide direct personnel access to the reactor face.
[0061] The removal process for the retube platform system 100, after the
retube is complete,
is the reverse of the installation process, with the final step being the
removal of the sole plates
and repair of the concrete/epoxy floor.
[0062] The retube platform system 100, and in particular the elevator
system 108, is operated
via one or more human-machine interfaces (HMIs). The elevator system 108
includes the servo
motors 124 as described above, or at least one alternate prime mover to move
the platform 106,
106' up and down on command. One operator, either on the platform 106, 106' or
on the vault
floor adjacent the platform, with spotters as required, operates the elevator
system 108 during
most operations. When the platform 106, 106' is at lower elevations, two
operators may be used
to ensure that interference with other adjacent structures is avoided. In this
case, one operator
may operate the elevator system 108, while the other operator holds a dead-man
switch while
spotting.
[0063] The maximum vertical speed of the platform 106, 106' may be about 90
inches per
minute, although operational speed may be set at about 45 inches per minute,
at which rate the
total travel time from the lowest position to the top position is no more than
approximately 6.2
minutes. This time only represents time spent moving, as other factors will
affect the total time
to initiate and complete a move of the platform 106, 106' between the upper
and lower limits
16

CA 02766591 2012-01-16
,
Attorney Docket No. 027813-9045-CA
(e.g., soft acceleration and deceleration up to and down from set movement
speed, and slower set
speed at lower elevations).
[0064] Operator screens on the human-machine interface are
simplified as much as possible,
reducing the error-likely situations encountered with congested menus. Simple
move and jog
screens are provided, with all other operations automated, and error feedback
to the operations
center where technical specialists will troubleshoot remotely, with operator
input minimized.
[0065] Supplementary collision mitigation systems may be provided
to further protect
personnel and equipment from process breakdowns and provide further protection
from
collisions with equipment in conjunction with detailed operating procedures.
17

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date 2018-03-27
(22) Filed 2012-01-16
(41) Open to Public Inspection 2012-07-15
Examination Requested 2016-10-20
(45) Issued 2018-03-27

Abandonment History

There is no abandonment history.

Maintenance Fee

Last Payment of $263.14 was received on 2023-12-21


 Upcoming maintenance fee amounts

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Next Payment if small entity fee 2025-01-16 $125.00
Next Payment if standard fee 2025-01-16 $347.00

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Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2012-01-16
Maintenance Fee - Application - New Act 2 2014-01-16 $100.00 2014-01-03
Maintenance Fee - Application - New Act 3 2015-01-16 $100.00 2015-01-13
Maintenance Fee - Application - New Act 4 2016-01-18 $100.00 2016-01-04
Request for Examination $800.00 2016-10-20
Maintenance Fee - Application - New Act 5 2017-01-16 $200.00 2017-01-04
Maintenance Fee - Application - New Act 6 2018-01-16 $200.00 2017-12-15
Final Fee $300.00 2018-02-07
Maintenance Fee - Patent - New Act 7 2019-01-16 $200.00 2019-01-15
Maintenance Fee - Patent - New Act 8 2020-01-16 $200.00 2020-01-10
Maintenance Fee - Patent - New Act 9 2021-01-18 $204.00 2021-01-08
Maintenance Fee - Patent - New Act 10 2022-01-17 $255.00 2021-12-16
Maintenance Fee - Patent - New Act 11 2023-01-16 $254.49 2022-12-16
Maintenance Fee - Patent - New Act 12 2024-01-16 $263.14 2023-12-21
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
ATOMIC ENERGY OF CANADA LIMITED
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 2012-01-16 1 19
Description 2012-01-16 17 937
Claims 2012-01-16 3 107
Drawings 2012-01-16 23 867
Representative Drawing 2012-03-13 1 37
Cover Page 2012-07-10 2 77
Amendment 2017-07-21 4 109
Claims 2017-07-21 3 92
Interview Record Registered (Action) 2017-07-28 1 18
Amendment 2017-07-31 4 134
Claims 2017-07-31 3 95
Final Fee 2018-02-07 2 72
Representative Drawing 2018-02-27 1 31
Cover Page 2018-02-27 1 64
Assignment 2012-01-16 6 168
Request for Examination 2016-10-20 1 51
Prosecution-Amendment 2016-11-16 1 27
Examiner Requisition 2016-12-01 5 285
Drawings 2017-02-28 23 863
Claims 2017-02-28 3 103
Description 2017-02-28 17 931
Amendment 2017-02-28 18 1,006
Examiner Requisition 2017-04-26 4 222