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Sommaire du brevet 2766586 

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Disponibilité de l'Abrégé et des Revendications

L'apparition de différences dans le texte et l'image des Revendications et de l'Abrégé dépend du moment auquel le document est publié. Les textes des Revendications et de l'Abrégé sont affichés :

  • lorsque la demande peut être examinée par le public;
  • lorsque le brevet est émis (délivrance).
(12) Brevet: (11) CA 2766586
(54) Titre français: OBTURATEUR INSERE POUR TUBE A TREILLIS DE REACTEUR NUCLEAIRE ET METHODE CONNEXE
(54) Titre anglais: NUCLEAR REACTOR LATTICE TUBE PLUG INSERT AND METHOD
Statut: Octroyé
Données bibliographiques
(51) Classification internationale des brevets (CIB):
  • G21C 13/06 (2006.01)
(72) Inventeurs :
  • SCOTT, DAVID (Canada)
  • SOLTI, GEORGE (Canada)
  • NOSELLA, LAWRENCE PAUL (Canada)
(73) Titulaires :
  • ATOMIC ENERGY OF CANADA LIMITED (Canada)
(71) Demandeurs :
  • ATOMIC ENERGY OF CANADA LIMITED (Canada)
(74) Agent: NORTON ROSE FULBRIGHT CANADA LLP/S.E.N.C.R.L., S.R.L.
(74) Co-agent:
(45) Délivré: 2018-03-06
(22) Date de dépôt: 2012-01-16
(41) Mise à la disponibilité du public: 2012-07-17
Requête d'examen: 2016-10-20
Licence disponible: S.O.
(25) Langue des documents déposés: Anglais

Traité de coopération en matière de brevets (PCT): Non

(30) Données de priorité de la demande:
Numéro de la demande Pays / territoire Date
61/433,325 Etats-Unis d'Amérique 2011-01-17

Abrégés

Abrégé français

Linvention propose un appareil et un procédé de blocage dun rayonnement dun réacteur nucléaire ayant au moins un tube de canal de combustible qui comprend linsertion dun obturateur dans une extrémité du tube de canal de combustible, procurant un joint étanche aux gaz avec lobturateur dans le tube de canal de combustible, et installant une bride autour de lobturateur et/ou autour de lextrémité dun manchon également inséré à lintérieur du tube de canal de combustible. Dans certains modes de réalisation, le manchon reçoit lobturateur et peut protéger le tube de canal de combustible et une ouverture de paroi dans laquelle lobturateur de canal de combustible est reçu contre des dommages. De même dans certains modes de réalisation, une fuite de rayonnement peut être réduite ou empêchée par lobturateur, la bride et/ou par un système détanchéité entre le manchon et lobturateur et/ou entre le manchon et le tube de canal de combustible.


Abrégé anglais

An apparatus and method of shielding radiation from a nuclear reactor having at least one fuel channel tube includes inserting a plug into an end of the fuel channel tube, providing a gas-tight seal with the plug in the fuel channel tube, and installing a flange about the plug and/or about the end of a sleeve also inserted within the fuel channel tube. In some embodiments, the sleeve receives the plug, and can protect the fuel channel tube and a wall aperture in which the fuel channel plug is received against damage. Also in some embodiments, radiation leakage can be reduced or prevented by the plug, the flange, and/or by a sealing arrangement between the sleeve and the plug and/or between the sleeve and the fuel channel tube.

Revendications

Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.





CLAIMS
What is claimed is:

1. A method of shielding radiation from a nuclear reactor having at least a
portion of an
open end of a tube of a fuel channel assembly, the method comprising:
inserting a plug into the open end of the tube;
sealing the plug within the tube against passage of gas along the tube and
past the plug;
and
installing a flange about at least one of the open end of the tube and the
plug, wherein the
flange substantially surrounds the at least one of the open end of the tube
and the plug.

2. The method of claim 1, further comprising installing a sleeve into the open
end of the
tube, wherein inserting the plug into the open end of the tube comprises
inserting the plug into
the sleeve.

3. The method of claim 2, further comprising fastening the flange to an end
shield with at
least one fastener.

4. The method of claim 2, wherein installing the flange comprises sliding the
flange on the
open end of the sleeve.

5. The method of claim 2, further comprising receiving the sleeve within a
portion of the
tube in axial alignment with an aperture in an end shield.

6. The method of claim 2, wherein sealing the plug comprises forming a seal
between the
plug and the sleeve.

7. The method of claim 2, further comprising forming a seal between the sleeve
and the tube
against passage of gas along the tube and past the sleeve.





8. The method of claim 1, further comprising removing the plug while keeping
the flange in
place after installing the flange.

9. The method of claim 1, further comprising removing the plug while keeping
the sleeve in
place after installing the flange.

10. The method of claim 1, wherein installing the flange comprises positioning
the flange to
cover and shield a portion of a face of the nuclear reactor.

11. The method of claim 10, further comprising repeating the inserting,
sealing, and
installing steps with multiple adjacent fuel channel assemblies, wherein
installing the flange in at
least some of the installing steps comprises orienting at least one side of
the flange with at least
one side of a flange corresponding to an adjacent fuel channel assembly.

12. The method of claim 1, further comprising maintaining a vacuum in the tube
with the
plug.

16




13. A method of installing a shield on a nuclear reactor having a plurality of
fuel channel
tubes, the method comprising:
inserting a first plug into an end of a first one of the fuel channel tubes;
coupling a first flange to the first one of the fuel channel tubes;
inserting a second plug into an end of a second one of the fuel channel tubes;

coupling a second flange to the end of the second one of the fuel channel
tubes;
positioning the first flange immediately adjacent the second flange; and
shielding radiation from the nuclear reactor with the first and second plugs
and with the
first and second flanges.

14. The method of claim 13, further comprising coupling the first flange to a
tube sheet with
a first fastener.

15. The method of claim 13, further comprising removing the first plug without
removal of
the first flange to permit access to an interior of the first fuel channel
tube.

16. The method of claim 13, further comprising removing the first flange
without removal of
the first plug to permit access to the tube sheet.

17. The method of claim 13, further comprising:
inserting a first sleeve into the first fuel channel tube; and
positioning the first sleeve between the first plug and the first fuel channel
tube.

18. The method of claim 17, wherein coupling the first flange to the first
fuel channel tube
comprises coupling the first flange to the first sleeve.

19. The method of claim 17, further comprising forming a seal between the
first sleeve and
the first fuel channel tube.

20. The method of claim 17, further comprising forming a seal between the
first sleeve and
the first plug.

17




21. The method of claim 13, further comprising:
releasably mating an end of the first plug with an end of an insertion tool;
and
inserting the first plug into the first tube with the insertion tool.

22. The method of claim 13, further comprising:
extending the first plug through an aperture in a tube sheet; and

positioning the first plug to be simultaneously within the aperture in the
tube sheet and
within the first sleeve.

23. The method of claim 13, further comprising removing one plate of the first
flange from at
least one other plate of the first flange.


18




24. A modular shield assembly for shielding radiation from a nuclear reactor
having a tube
sheet defining a plurality of apertures and a plurality of fuel channel tubes
each extending
through a respective one of the plurality of apertures in the tube sheet, the
assembly comprising:
a plurality of discrete shields, each shield including
a sleeve insertable into an end of one of the plurality of fuel channel tubes,
a plug insertable into the end of the one of the plurality of fuel channel
tubes, and
a flange couplable to the one of the plurality of fuel channel tubes;
wherein at least one of the plug and the flange is removable from the
corresponding fuel
channel tube without requiring removal of adjacent shields; and
wherein the shields collectively define a substantially continuous wall
covering at least a
portion of the tube sheet to shield radiation from the nuclear reactor.

25. The assembly of claim 24, wherein each of the plugs is separately
removable from the
respective one of the fuel channel tubes.

26. The assembly of claim 24, wherein each of the flanges is separately
removable from the
respective one of the fuel channel tubes.

27. The assembly of claim 24, further comprising a plurality of fasteners
extending through
respective apertures in the flanges and into respective holes in the tube
sheet.

28. The assembly of claim 24, wherein each of the flanges is substantially
square and
includes an aperture through which a respective one of the sleeves extends.

19




29. The assembly of claim 24, wherein:
the flanges collectively form a wall spaced from the tube sheet;
the wall defines apertures extending therethrough; and
the apertures in the wall are substantially aligned with the apertures in the
tube sheet.
30. The assembly of claim 24, wherein each plug extends into a respective
aperture in the
tube sheet and into a respective sleeve.

31. The assembly of claim 24, wherein each sleeve forms a gas-tight seal
within a respective
fuel channel tube in which the sleeve is received.

32. The assembly of claim 24, wherein each plug forms a gas-tight seal within
a respective
sleeve in which the plug is received.

33. The assembly of claim 24, wherein the plurality of discrete shields seal
the fuel channel
tubes to maintain a substantial vacuum inside the fuel channel tubes.

34. The assembly of claim 33, wherein the substantial vacuum inhibits escape
of radioactive
particles from the fuel channel tubes when the discrete shields are removed
from the fuel channel
tubes.





35. A modular shield assembly for shielding radiation from a nuclear reactor
having a tube
sheet defining a plurality of apertures and a plurality of fuel channel tubes
each extending
through a respective one of the plurality of apertures in the tube sheet, the
assembly comprising:
a sleeve insertable into an end of one of the plurality of fuel channel tubes,
the sleeve
extending through one of the apertures in the tube sheet;
a plug insertable into the end of the one of the plurality of fuel channel
tubes, the plug
extending through the one of the apertures in the tube sheet and located
within the sleeve,
wherein the plug forms a shield to block radiation within the one of the
plurality of fuel channel
tubes from escaping to atmosphere; and
a flange releasably couplable to the one of the plurality of fuel channel
tubes to
substantially surround at least one of the sleeve and the plug in a position
shielding radiation
from the nuclear reactor escaping to atmosphere.

36. The assembly of claim 35, wherein the sleeve and the plug are located
within the flange.
37. The assembly of claim 35, wherein the plug and flange are independently
removable
from the one of the plurality of fuel channel tubes.

38. The assembly of claim 37, wherein removal of the plug provides access into
the one of
the plurality of fuel channel tubes.

39. The assembly of claim 37, wherein removal of the flange provides access to
the tube
sheet.

40. The assembly of claim 35, further comprising a fastener adapted to extend
through an
aperture in the flange and into a hole in the tube sheet to couple the flange
to the tube sheet.

41. The assembly of claim 35, wherein the flange is substantially square and
defines a flange
aperture substantially the same size as the one of the plurality of apertures
in the tube sheet.

21




42. The assembly of claim 35, wherein in at least one position of the plug
within the sleeve,
the plug is provided with a gas-tight seal within the sleeve.


22

Description

Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.


CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
NUCLEAR REACTOR LATTICE TUBE PLUG INSERT AND METHOD
RELATED APPLICATIONS
[0001] The present application claims priority to U.S. Provisional
Application No.
61/433,325 of the same title, filed January 17, 2011.
FIELD OF THE INVENTION
[0002] The present invention relates to methods, devices, and systems for
retubing nuclear
reactors.
SUMMARY
[0003] A nuclear reactor has a limited life of operation. For example,
second generation
CANDUTm-type reactors ("CANada Deuterium Uranium") are designed to operate for

approximately 25 to 30 years. After this time, the existing fuel channels can
be removed and
new fuel channels can be installed. Performing this "retubing" process can
extend the life of a
reactor. For example, retubing a CANDUTm-type reactor can extend the reactor's
life by an
additional 25 to 40 years. Without performing the retubing, a reactor that
reaches the end of its
useful life is typically decommissioned and replaced with a new reactor, which
poses significant
costs and time. Alternatively, replacement energy sources may be used to
extend the life of a
reactor. However, replacement energy sources are often more expensive than
installing a new
reactor, and can be difficult to acquire.
[0004] Nuclear reactor retubing processes include removal of a large number
of reactor
components, and include various other activities, such as shutting down the
reactor, preparing the
vault, and installing material handling equipment and various platforms and
equipment supports.
In the process of removing reactor components, it is sometimes necessary to
remove end fittings
of the reactor fuel channels, and to insert sleeves, plugs, or other
components in the unoccupied
reactor lattice sites.
[0005] During the removal process, particular procedures can be used to
improve the
efficiency of the process. For example, a stand-alone retube tooling platform
can be installed on
each face of the reactor, which is used to support operators and tools during
the retubing process.
1

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
Also, when components are removed from the reactor, they must be transported
and disposed of
properly. In some embodiments, the components are volume reduced before being
transported,
such as by cutting the components into smaller pieces.
[0006] As mentioned above, it is often necessary in the process of retubing
a nuclear reactor
to insert components in lattice sites left unoccupied during the retubing
process. In some cases,
lattice shield plugs can be installed in such sites. Based at least in part
upon the relatively large
number of such lattice sites in a typical reactor and the collective time
consumed in insertion and
removal operations, new and improved lattice tube shield plugs and methods of
inserting such
plugs are welcome additions to the art.
[0007] Embodiments of the present invention provide lattice tube shield
plug inserts and
lattice tube shield plug insert and removal tools and methods which can be
used to improve
nuclear reactor retubing operations and nuclear reactors that have been
retubed.
[0008] Some embodiments of the present invention provide a method of
shielding radiation
from a nuclear reactor having at least a portion of an open end of a tube of a
fuel channel
assembly, wherein the method comprises: inserting a plug into the open end of
the tube; sealing
the plug within the tube against passage of gas along the tube and past the
plug; and installing a
flange about at least one of the open end of the tube and the plug, wherein
the flange
substantially surrounds the at least one of the open end of the tube and the
plug.
[0009] In some embodiments, a method of installing a shield on a nuclear
reactor having a
plurality of fuel channel tubes is provided, and comprises: inserting a first
plug into an end of a
first one of the fuel channel tubes; coupling a first flange to the first one
of the fuel channel
tubes; inserting a second plug into an end of a second one of the fuel channel
tubes; coupling a
second flange to the end of the second one of the fuel channel tubes;
positioning the first flange
immediately adjacent the second flange; and shielding radiation from the
nuclear reactor with the
first and second plugs and with the first and second flanges.
[0010] Some embodiments of the present invention provide a modular shield
assembly for
shielding radiation from a nuclear reactor having a tube sheet defining a
plurality of apertures
and a plurality of fuel channel tubes each extending through a respective one
of the plurality of
2

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
apertures in the tube sheet, wherein the assembly comprises: a plurality of
discrete shields, each
shield including a sleeve insertable into an end of one of the plurality of
fuel channel tubes, a
plug insertable into the end of the one of the plurality of fuel channel
tubes, and a flange
couplable to the one of the plurality of fuel channel tubes; wherein at least
one of the plug and
the flange is removable from the corresponding fuel channel tube without
requiring removal of
adjacent shields; and wherein the shields collectively define a substantially
continuous wall
covering at least a portion of the tube sheet to shield radiation from the
nuclear reactor.
[0011] In some embodiments, a modular shield assembly for shielding
radiation from a
nuclear reactor having a tube sheet defining a plurality of apertures and a
plurality of fuel
channel tubes each extending through a respective one of the plurality of
apertures in the tube
sheet is provided, and comprises: a sleeve insertable into an end of one of
the plurality of fuel
channel tubes, the sleeve extending through one of the apertures in the tube
sheet; a plug
insertable into the end of the one of the plurality of fuel channel tubes, the
plug extending
through the one of the apertures in the tube sheet and located within the
sleeve, wherein the plug
forms a shield to block radiation within the one of the plurality of fuel
channel tubes from
escaping to atmosphere; and a flange releasably couplable to the one of the
plurality of fuel
channel tubes to substantially surround at least one of the sleeve and the
plug in a position
shielding radiation from the nuclear reactor escaping to atmosphere.
[0012] Other aspects of the invention will become apparent by consideration
of the detailed
description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013]rm
Fig. 1 is a perspective view of a CANDU reactor.
[0014]
Fig. 2 is a cut away view of a CANDU m-type nuclear reactor fuel channel
assembly.
[0015] Fig. 3 is a close up perspective view of the connection between the
tube sheet and the
bellows, the bellows ferrules, and the end fitting of Fig. 2.
3

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
100161 Fig. 4 is a perspective view of a lattice site shield plug insert
and removal tool in
conjunction with other tools according to an embodiment of the present
invention, shown
installed before a reactor face.
[0017] Fig. 5 is a cross sectional view of lattice sleeve assemblies each
having a lattice shield
plug, according to an embodiment of the present invention.
[0018] Fig. 6 is a perspective view of a lattice site shield plug insert
and removal tool
according to an embodiment of the present invention.
[0019] Fig. 7 shows the lattice site shield plug insert and removal tool of
Figs. 4 and 6
advancing with a lattice sleeve assembly attached thereto and in the process
of installing the
lattice sleeve assembly into a lattice site.
[0020] Fig. 8 shows the lattice site shield plug insert and removal tool of
Figs. 4 and 6, fully
advanced with the lattice sleeve assembly installed into a lattice site.
[0021] Fig. 9 is a close up perspective view of a reactor face with several
lattice shield plug
assemblies installed, according to an embodiment of the present invention.
[0022] Fig. 10 is a perspective view of a reactor face in which all lattice
sleeve assemblies
have been installed in lattice sites on the reactor face, according to an
embodiment of the present
invention.
DETAILED DESCRIPTION
[0023] 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
accompanying drawings. The invention is capable of other embodiments and of
being practiced
or of being carried out in various ways.
[0024] 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
4

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
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 apertures that each
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.
[0025] As in the illustrated embodiment, in some embodiments the reactor
core is provided
with two walls at each end 22, 24 of the reactor core: an inner wall defined
by the tube sheet 18
at each end 22. 24 of the reactor core, and an outer wall 64 (often referred
to as a "end shield")
located a distance outboard from the tube sheet 18 at each end 22, 24 of the
reactor core. A
lattice tube 65 spans the distance between the tube sheet 18 and the end
shield 64 at each pair of
apertures (i.e., in the tube sheet 18 and the end shield 64, respectively).
[0026] FIG. 2 is a cut away view of the fuel channel assembly 28. As
illustrated in FIG. 2,
each fuel channel assembly 28 includes a calandria tube ("CT") 32 surrounding
other
components of the fuel channel assembly 28. The CTs 32 each span the distance
between the
tube sheets 18. Also, the opposite ends of each CT 32 are received within and
sealed to
respective apertures in the tube sheets 18. In some embodiments, a CT rolled
joint insert 34 is
used to secure the CT 32 to the tube sheet 18 within the bores, although other
tube-to-sheet
joining structures and methods can instead be used. In this manner, the CTs 32
each form a first
boundary between the heavy water moderator of the calandria 10 and the
interior of the fuel
channels assemblies 28.
[0027] 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 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
each PT 36 and its corresponding 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 typically having at
least one of 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.

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
Second, the annulus gas system provides indication of a leaking calandria tube
32 or pressure
tube 36 via the presence of moisture, deuterium, or both detected in the
annulus gas.
[0028] 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 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.
[0029] As also shown in FIG. 2, each end of each fuel channel assembly 28
is provided with
an end fitting 50 located outside of the corresponding tube sheet 18. At the
terminal end 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 fittings 50 using a coupling assembly 56
including a number of
screws, washers, seals, and/or other types of connectors.
[0030] The lattice tube 65 (described above) 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.
[0031] With continued reference to FIGS. 2 and 3, coolant from the inlet
feeder assembly 54
flows along a perimeter channel of the end fitting 50 until it reaches a
shield plug 58. The shield
plug 58 is contained within the PT 36 and the lattice tube 65, and includes a
number of openings
that allow the coolant provided by the inlet feeder assembly to enter the end
of the PT 36.
Another shield plug 58 is located within the PT 36 and the lattice tube 65 at
the other end of the
fuel channel assembly 28, and 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.
6

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
[0032] Returning to FIGS. 2 and 3, 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 ¨ a capability that can be important where fuel channel
assemblies 28 experience
changes in length over time, which is common in many reactors. The positioning
hardware
assemblies 60 can be used to set an end of a fuel channel assembly 28 in
either a locked or an
unlocked position. In the locked position, the end of the fuel channel
assembly 28 is fixed in an
axial position. In the unlocked position, the end of the fuel channel assembly
28 is allowed to
move axially. A tool can be used with the positioning hardware assemblies 60
to switch the
position of a particular fuel channel assembly 28.
100331 The positioning hardware assemblies 60 are also coupled to the end
shield 64. The
positioning hardware assemblies 60 each include a rod having an end that is
received in a bore of
the respective end shield 64. In some embodiments, the rod end and the bore in
the end shield 64
are threaded.
[0034] It should be understood that although a CANDUT"-type reactor is
illustrated in FIGS.
1-3, the methods and systems described below for retubing a reactor also apply
to other types of
reactors containing similar components as illustrated in FIGS. 1-3.
[0035] As shown in FIG. 4, the various tools utilized in the present
invention can be installed
and/or used adjacent the calandria 10 of the nuclear reactor 6 on a mobile
table 70. The table 70
can carry and support tooling from lattice site to lattice site (i.e., those
positions on each side of
the reactor 6 defined by the locations of the fuel channel assemblies 28
described above) across
the face of the calandria 10. In some embodiments, the table 70 is laterally
movable in an x
direction (e.g., upon rails, on a cart, and the like) at a common elevation
across the face of the
calandria 10, whereas in other embodiments, the table 70 is also vertically
movable in a y
direction and/or is movable toward and away from the reactor face in a z
direction. By way of
example, in some embodiments, the table 70 is movable in x and z directions,
and is mounted
upon a retube tooling platform 72 ("RTP") assembled in front of the calandria
face and vertically
movable (in the y direction) to different lattice sites. In some embodiments,
the RTP 72 is an
adjustable platform upon which much of the fuel channel component removal
operations are
performed. Also in some embodiments, the RTP 72 is a stand-alone machine that
does not rely
7

CA 2766586 2017-03-16
Attorney Docket No. 027813-9033-CA00
on existing plant structures for positioning or movement, and is adapted to
adjustably support
one or more tables.
100361 In some instances, it is desirable to insert a plug into an
unoccupied lattice site
resulting from nuclear reactor retubing operations. By way of example only,
during re-tubing
operations of CANDU I m reactors, all end fittings 50 are removed from the
CANDU TM reactor.
The end fittings 50 are illustrated schematically in FIG. 4. Using end fitting
removal tooling on
platforms located on opposite ends 22, 24 of the reactor 6 (which can be
identical, in some
embodiments), the end fittings 50 can be removed from the same fuel channel
assembly 28 from
opposite reactor faces. In such cases, the end fittings 50 of the same fuel
channel assembly 28
can be removed in a staggered fashion to accommodate end fitting flask trolley
vault traffic.
After end fitting removal, it will be necessary in some cases to plug the
lattice site.
[0037] After an end fitting 50 is removed from a fuel channel assembly 28,
a lattice sleeve
shield plug insertion and removal tool 74 (LS-SPIRT) can insert a lattice
sleeve assembly 76
(LSA, also referred to as a "thumbtack") into the remainder of the fuel
channel assembly 28 to
attenuate radiation that could otherwise emit from the open channel and/or
tube sheet face
adjacent the open channel. As an additional valuable feature, once the LSA is
installed in a
lattice site, the LSA 76 can function as a portal through the end shield 64
through which tooling
and reactor parts can be passed into and out of the reactor during re-tubing
operations.
Accordingly, the LSA 76 can protect the aperture at the lattice site from
damage while tooling
and reactor parts are moved through the aperture. For example, it may be
necessary to insert
tooling through the end shield aperture and lattice tube 65 at a lattice site
in order to remove
portions of a fuel channel assembly 28 (e.g., split ring, PT, and/or CT of the
fuel channel
assembly 28, and the like). Also, and as will be discussed in greater detail
below, the LSA 76
can provide a constant-diameter aperture by which proper tool and reactor part
alignment and
orientation are achieved. More particularly, an inner aperture through the LSA
76 can provide a
bearing surface for tooling inserted into the end aperture of the lattice
site.
100381 In some embodiments (and as will be described in greater detail
below), the LSA 76
can also be used to plug the lattice site and form a seal to maintain a vacuum
within the calandria
8

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
10, and/or can providing a tooling interface between the LS-SPIRT 74 and the
LSA 76 for LSA
installation and removal operations.
[0039] With reference back to FIGs. 2 and 3, an example of a LSA 76
application will now
be described. In order to remove or service components of the fuel channel
assembly 28 during a
re-tubing operation, the outlet feeder assembly 54 and the positioning
hardware assembly 60 are
typically removed first, followed by removal of the closure plug 52. Removal
of the closure plug
52 permits access to the inside of the end fitting 50 by appropriate tooling
to sever the end fitting
50. Although the end fitting 50 can be severed at any desired location, in
some embodiments
(and with particular reference to FIG. 3), the end fitting 50 is severed at
the ferrule on either end
of the bellows 62 depending upon whether it is desirable to keep the bellows
62 intact after the
retubing operations, to inspect the bellows 62 for damage or deterioration, or
to replace the
bellows 62. In the illustrated embodiment, the end fitting 50 has been severed
at the inboard
ferrule of the bellows 62, and so is not shown in FIG. 5. (Only the remainder
of the inboard
ferrule is visible between the flange 82 and the end shield 64 of each LSA 76
in FIG. 5, the rest
of the bellows 62 of each LSA already having been removed).
[0040] After the end fitting 50 has been severed and removed (with the
bellows 62 also
removed as shown in the illustrated embodiment, or with the bellows 62 still
intact at the lattice
site), the open lattice site can be plugged with an LSA as described herein.
In some applications,
LSAs 76 are inserted into each lattice tube 65 immediately after the end
fitting 50 thereof has
been severed and extracted.
[0041] As shown in FIG. 5, the LSA 76 of the illustrated embodiment
includes three major
components: a sleeve 78, a shield plug 80, and a flange 82. These components
of the LSA 76
can all be made from steel with a smooth plated surface finish to inhibit
corrosion and promote
easy decontamination, although other materials are possible. In some
embodiments, the outer
diameter of the sleeve 78 can provide a clearance fit with the inner diameter
of the lattice tube,
and/or the inner diameter of the sleeve 78 can be the same as that of the
inner diameter of the
lattice tube 65 inboard of the fully-inserted LSA 76 (see FIG. 5) or of any
component (e.g., split
bearing ring) similarly located. Once installed as shown in FIG. 5, the sleeve
78 protects the
9

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
aperture in the end shield 64 and the lattice tube 65 from contact and
possible damage by tooling
and reactor parts moving through the sleeve 78 and lattice tube 65.
[0042] In some embodiments, one or more seals are provided between the
inside of the
lattice tube 65 and the outside or end of the sleeve 78 when fully installed.
By way of example
only, the inboard end of the sleeves 78 shown in FIG. 5 are provided with at
least one annular
seal 69 (e.g., 0-ring, labyrinth, and the like) carried by or otherwise
located on the sleeve 78.
Alternatively or in addition, such seal(s) can be carried by or otherwise
located on the lattice tube
65. With reference to the embodiment of FIG. 5, the seal(s) can match the
inner diameter of that
portion of the lattice tube 65 where the seals 69 are positioned when the LSA
76 is fully
installed. For example, the inner diameter of the lattice tubes 65 in FIG. 5
are reduced at a
shoulder located proximate the tube sheet 18, in which case the seals 69 are
located on a
similarly-reduced exterior diameter of the sleeve 78 to provide a seal between
the sleeve 76 and
the lattice tube 65. The seal generated by the seal(s) 69 are preferably gas-
tight and do not
permit gas or other fluid leakage despite a vacuum being maintained within the
CT 32. It will be
appreciated that any other suitable type of seal or sealing method can instead
be utilized as
desired.
[0043] With continued reference to the embodiment of FIG. 5, each of the
LSAs 76 includes
an internal shield plug 80. Although in some embodiments the sleeve 78 and
shield plug 80 are
integral (in which cases the sleeve 78 and shield plug 80 would have to be
removed together for
tooling and reactor part passage through the lattice tube in retubing
operations), the shield plug
80 and sleeve 78 are separate parts in the illustrated embodiment.
Accordingly, the shield plug
80 can be removed from the sleeve 78 in order to access the interior of the
fuel channel 28. In
some embodiments, the shield plug 80 can comprise a removable core, such as a
2" removable
core, or a core having any other shape with an exterior surface at least
partially matching the
interior surface of the sleeve 78 into which the shield plug 80 is inserted.
The shield plug 80 can
be constructed of a single element or of multiple elements secured together to
collectively
perform the functions described here.
[0044] In some embodiments, a gas-tight seal is provided between the shield
plug 80 and the
sleeve 78 when the shield plug 80 is installed within the sleeve 78, such as
to retain a vacuum

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
within the CT 32. Such a seal can be provided in any of the manners described
above in
connection with the gas-tight seal(s) between the sleeve 78 and the lattice
tube 65, such as by one
or more annular seals located between an inside diameter of the sleeve 78 and
an outside
diameter of the shield plug 80. However, in the illustrated embodiment, the
shield plug 80 of
each LSA 76 includes an annular shoulder 85 that overlaps the end of the
corresponding sleeve
78 to form a seal between the sleeve 78 and the shield plug 80, as well as
compensate for
tolerance variations. This seal can be rolled or formed in any other suitable
manner.
[0045] By utilizing appropriate seals between the sleeve 78 and the lattice
tube 65, and
between the shield plug 80 and the sleeve 78 as described herein, the LSA can
substantially seal
the lattice tube 65 from atmosphere while maintaining a negative pressure in
the calandria 10 to
inhibit leakage of radioactive material from inside the calandria 10 to
atmosphere.
[0046] Each of the shield plugs 80 illustrated in FIG. 5 include a recess
84 at an outboard end
of the shield plug (i.e., proximate the flange 82 of the shield plug 80). The
recess 84 defines a
mating feature for engagement by the LS-SPIRT 74 in order to insert the shield
plug 80 into the
sleeve 78 and flange 82, to remove the shield plug 80 from the sleeve 78 and
flange 82, or to
insert or remove the entire LSA 76 with respect to a lattice site. The recess
84 can also have a
deeper center hole for registration with a mating protrusion of the LS-SPIRT
74 for purposes of
proper registration between the LS-SPIRT 74 and the shield plug 80 during such
operations.
Although a recess 84 is provided in each of the shield plugs 80 of the
illustrated embodiment, it
should be noted that any other mating feature(s) can be utilized for
releasably coupling the shield
plug 80 (and therefore the entire LSA 76) to the LS-SPIRT 74, such as a
protrusion of the shield
plug 80 for releasable mating engagement in a recess at the end of the LS-
SPIRT 75, mating
bayonet fitting features on the shield plug 80 and LS-SPIRT 74, and the like.
[0047] As described above, each of the LSAs 76 in the illustrated
embodiment has a flange
82. With reference to FIG. 5, when the LSAs are installed as described herein,
the flanges 82
provide another layer of radiation protection by defining (with the shield
plugs 80 and the ends
of the sleeves 78 of the LSAs 76) a modular wall across the end shield 64. To
this end, each of
the flanges 78 has a shape matching the adjoining edges of adjacent flanges
78. As shown in
FIG. 7 by way of example only, the flanges 78 in the illustrated embodiment
are square.
11

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
However, depending at least in part upon the arrangement of fuel channel
assemblies 28 across
the reactor faces, other flange shapes are entirely possible, such as
triangular, hexagonal, and
other polygonal flanges 78. In still other embodiments, two or more different
flange shapes can
be used across the reactor faces to provide options for other polygonal,
round, rotund, irregular,
or other flange shapes. As with the illustrated embodiment, the alternative
flange shapes can
still cooperate to provide a substantially gapless wall across the end shield
64 for additional
radiation protection. Furthermore, and in contrast to conventional radiation
shields for nuclear
reactors, the modularity provided by enabling removal and replacement of
individual flanges
corresponding to lattice sites is a significant advancement over designs in
which only the entire
end shield or similar wall can be removed and replaced or cut. In this regard,
the use of LSAs 76
as disclosed herein enable service of particular fuel channel assemblies 28
without disturbing the
rest of the radiation shielding wall provided by the flanges of other LSAs 76
already in place.
[0048] As shown in FIG. 5, the flange 82 of each LSA 76 includes three
overlapping plates.
In other embodiments, any number of such plates (e.g., 1, 2, more the 4) can
be used as desired.
By using multiple plates 82, service personnel can more easily remove the
flanges 82 (which can
have significant weight, in some embodiments). Also, a flange design
permitting the installation
of multiple plates enables service personnel to select the appropriate level
of radiation shielding
by installing the number of plates desired across the reactor face. In this
regard, the plates 82 on
any LSA 76 can each have the same thickness or have different thicknesses as
desired.
[0049] In some embodiments, at least one (and in some cases, more than one
or all) of the
plates of each flange 82 are integral or otherwise permanently installed on
the sleeve 78 and/or
shield plug 80. Therefore, in such embodiments, removal of the entire flange
82 can require
removal of the sleeve 78 and/or shield plug 80. However, in the illustrated
embodiment, all
plates of the LSA 76 are removable for maximum modularity, adjustability, and
installation
flexibility. By enabling removal of the plates of the flange 82, access to the
tube sheet face 64
can be provided without having to remove the sleeve 78 or plug 80. In some
embodiments,
proper axial registration of the flange plates on the sleeve 78 is provided by
an annular rib,
collar, or other protrusion(s) formed on or attached to an exterior surface of
the sleeve 78. With
such features, the plates can be pushed into position on the sleeves 78 until
they are stopped
12

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
against such features, thereby preventing possible damage to the bellows 62,
bellows ferrule, or
other portion of the fuel channel assembly 28 behind the flange 82.
[0050] FIG. 6 illustrates an example of the LS-SPIRT 74 in greater detail.
The illustrated
LS-SPIRT 74 includes a housing 86, grippers 88 and a drive mechanism 90. The
drive
mechanism 90 moves the housing 86 and the grippers 88 in the direction of
arrow 92 with
respect to the table 70 shown in HG. 4 (i.e. toward and away from the
calandria 10). The
grippers 88 are at least partially insertable into the bores 84 of the LSAs
76, and can include at
least one axially adjustable shoe, pin, wedge, or other component that
selectively engages the
inside surface of the bores 84 of the LSAs 76 to grip the shield plug 80 of
the LSAs. Suitable
gripping tools are known in the art, and are not therefore described further
herein.
[0051] By gripping the inside surface of a bore 84 of an LSA 76, the LS-
SPIRT 74 can insert
or remove the plug 80 of the LSA 76, can insert or remove the plug 80 and
sleeve 78 of the LSA
with respect to a lattice tube 65 at a lattice site and/or can insert or
remove the entire LSA (i.e.,
with the flange 82) with respect to a lattice tube 65 at a lattice site.
Operation of the LS-SPIRT
74 can be controlled by an operator either on the RTP 72 or in a remote
location.
[0052] FIG. 7 illustrates the LS-SPIRT 74 engaging an LSA 76 with the LSA
76 spaced from
the end shield 64 of the calandria 10. The position illustrated in FIG. 7
shows the LSA 76 prior
to insertion into the lattice tube 65 or after removal of the LSA 76 from the
lattice tube 65. The
end fittings 50 shown in FIGS. 7-9 are shown schematically.
[0053] FIG. 8 illustrates the LS-SPIRT 74 engaging the LSA 76 with the LSA
76 fully
inserted into the lattice tube 65 at a lattice site. The position illustrated
in FIG. 8 shows the LSA
76 after insertion into the lattice tube 65 or prior to removal of the LSA 76
from the lattice tube
65.
[0054] FIG. 9 illustrates the tube sheet 64 after a number of end fittings
50 have been
removed from the reactor face, and after a number of LSAs 76 have been
installed. Some
embodiments of the present invention utilize one or more fasteners 94 (e.g.,
bolts, in the
illustrated embodiment) to secure the LSAs 76 to the fuelling machine tube
sheet 64. This
fastener installation process can be a manual face series operation in some
embodiments, and can
13

CA 02766586 2012-01-16
Attorney Docket No. 027813-9033-CA00
rely upon use of the RTP 72 (with optional front extensions 96) and various
tooling to facilitate
access to the LSAs 76. Commercial hand tools can be used for installing the
fastener 94. In
some embodiments, the fasteners 94 can facilitate separation of the components
of the LSAs 76,
such as to permit removal of the flange 82 without disturbing the sleeve 78
and/or plug 80 of an
LSA 80, or (in non-illustrated embodiments), to permit removal of the sleeve
78 and/or the plug
80 while the flange 82 remains installed. The fasteners 94 can be inserted
into the bore of the
respective tube sheet 64 previously occupied by the rod of the respective
positioning hardware
assemblies 60. To this end, apertures in the flanges 82 can permit passage of
the fasteners 94,
which can be threaded into the bores of the tube sheet 64. The apertures in
the flanges 82 of the
illustrated embodiment are unthreaded, but can be threaded in other
embodiments.
[0055] Once many of the LSAs 76 of the illustrated embodiment are installed
on the reactor
face, the flanges 82 together create thick shielding wall (e.g., of steel)
that reduces exposure to
radiation fields in front of the reactor face. By way of example only, in some
embodiments the
flanges 82 together create a 2" thick steel wall of shielding, thereby
reducing exposure to
radiation fields by a factor of eight. FIG. 10 shows all of the LSAs 76
installed on a reactor face.
One or more of the LSAs 76 can be removed to permit access to one or more of
the lattice tubes
65 and/or the tube sheet face 64. For example, one of the plugs 80 or one of
the flanges 82 can
be removed while the remaining plugs 80 and flanges 82 (as well as sleeves 78)
remain on the
reactor 6. This permits an operator to access a specific portion of the
calandria 10 without
exposing the operator to an excessive amount of the radiation emitted from the
calandria 10.
[0056] The embodiments described above and illustrated in the figures are
presented by way
of example only and are not intended as a limitation upon the concepts and
principles of the
present invention. As such, it will be appreciated by one having ordinary
skill in the art that
various changes in the elements and their configuration and arrangement are
possible without
departing from the spirit and scope of the present invention as set forth in
the appended claims.
14

Dessin représentatif
Une figure unique qui représente un dessin illustrant l'invention.
États administratifs

Pour une meilleure compréhension de l'état de la demande ou brevet qui figure sur cette page, la rubrique Mise en garde , et les descriptions de Brevet , États administratifs , Taxes périodiques et Historique des paiements devraient être consultées.

États administratifs

Titre Date
Date de délivrance prévu 2018-03-06
(22) Dépôt 2012-01-16
(41) Mise à la disponibilité du public 2012-07-17
Requête d'examen 2016-10-20
(45) Délivré 2018-03-06

Historique d'abandonnement

Il n'y a pas d'historique d'abandonnement

Taxes périodiques

Dernier paiement au montant de 263,14 $ a été reçu le 2023-12-21


 Montants des taxes pour le maintien en état à venir

Description Date Montant
Prochain paiement si taxe applicable aux petites entités 2025-01-16 125,00 $
Prochain paiement si taxe générale 2025-01-16 347,00 $

Avis : Si le paiement en totalité n'a pas été reçu au plus tard à la date indiquée, une taxe supplémentaire peut être imposée, soit une des taxes suivantes :

  • taxe de rétablissement ;
  • taxe pour paiement en souffrance ; ou
  • taxe additionnelle pour le renversement d'une péremption réputée.

Les taxes sur les brevets sont ajustées au 1er janvier de chaque année. Les montants ci-dessus sont les montants actuels s'ils sont reçus au plus tard le 31 décembre de l'année en cours.
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Historique des paiements

Type de taxes Anniversaire Échéance Montant payé Date payée
Le dépôt d'une demande de brevet 400,00 $ 2012-01-16
Taxe de maintien en état - Demande - nouvelle loi 2 2014-01-16 100,00 $ 2014-01-03
Taxe de maintien en état - Demande - nouvelle loi 3 2015-01-16 100,00 $ 2015-01-13
Taxe de maintien en état - Demande - nouvelle loi 4 2016-01-18 100,00 $ 2016-01-04
Requête d'examen 800,00 $ 2016-10-20
Taxe de maintien en état - Demande - nouvelle loi 5 2017-01-16 200,00 $ 2017-01-04
Taxe de maintien en état - Demande - nouvelle loi 6 2018-01-16 200,00 $ 2017-12-15
Taxe finale 300,00 $ 2018-01-17
Taxe de maintien en état - brevet - nouvelle loi 7 2019-01-16 200,00 $ 2019-01-15
Taxe de maintien en état - brevet - nouvelle loi 8 2020-01-16 200,00 $ 2020-01-10
Taxe de maintien en état - brevet - nouvelle loi 9 2021-01-18 204,00 $ 2021-01-08
Taxe de maintien en état - brevet - nouvelle loi 10 2022-01-17 255,00 $ 2021-12-16
Taxe de maintien en état - brevet - nouvelle loi 11 2023-01-16 254,49 $ 2022-12-16
Taxe de maintien en état - brevet - nouvelle loi 12 2024-01-16 263,14 $ 2023-12-21
Titulaires au dossier

Les titulaires actuels et antérieures au dossier sont affichés en ordre alphabétique.

Titulaires actuels au dossier
ATOMIC ENERGY OF CANADA LIMITED
Titulaires antérieures au dossier
S.O.
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Description du
Document 
Date
(yyyy-mm-dd) 
Nombre de pages   Taille de l'image (Ko) 
Abrégé 2012-01-16 1 19
Description 2012-01-16 14 789
Revendications 2012-01-16 8 212
Dessins 2012-01-16 10 451
Dessins représentatifs 2012-03-13 1 33
Page couverture 2012-07-10 1 64
Modification 2017-07-06 2 45
Description 2017-07-06 14 728
Taxe finale 2018-01-17 2 72
Dessins représentatifs 2018-02-07 1 21
Page couverture 2018-02-07 1 53
Cession 2012-01-16 5 163
Requête d'examen 2016-10-20 1 52
Poursuite-Amendment 2016-11-16 1 27
Modification 2017-03-16 23 1 137
Demande d'examen 2017-03-27 4 252
Description 2017-03-16 15 782
Dessins 2017-03-16 10 457
Demande d'examen 2017-05-04 3 161