Combined calandria tube insert release and removal tool and method of using same

Abstract

A device and method for removing a rolled joint insert are provided. The device comprising: a body extending axially from a first end to a second end; a carriage coupled to the first end. The carriage is configured to extend or retract the body into or out of a lattice site of the fuel channel assembly. The device also comprises a tool head having a distal end and a proximate end, the proximate end is coupled to the second end of the body, and the distal end has a surface configured to push an end of a pressure tube in a nuclear fuel channel to expose the rolled joint. The tool head comprises: a heater for heating the rolled joint insert; a removal member for removing the rolled joint; and at least one centering member for centering the tool head in the lattice site.

Description

COMBINED CALANDRIA TUBE INSERT RELEASE AND REMOVAL TOOL AND METHOD OF USING SAMECROSS REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY

[0001] The present application claims priority to U.S. provisional patent application no. 63 / 584,055 filed on September 20, 2023, the entire contents of which are hereby incorporated by reference.TECHNICAL FIELD

[0002] The disclosure relates generally to nuclear reactor fuel channel assemblies, and more particularly to removing nuclear reactor fuel channel assemblies at end of life.BACKGROUND

[0003] A nuclear reactor has a limited operational life. 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 significantly, as an alternative to decommissioning the reactor. 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. The removal process can also include removing closure plugs and positioning hardware assemblies, disconnecting feeder assemblies, severing bellows, removing end fittings, releasing and removing calandria tube inserts, severing and removing pressure tubes, and removing calandria tubes.

[0004] After the removal process is complete, an inspection and installation process is typically performed. For example, tube sheets positioned at each end of the reactor include a plurality of bores. Each of the plurality of bores supports a fuel channel assembly that spans between the tube sheets. When a fuel channel assembly is removed, each tube sheet bore is inspected to ensure that the removal of the fuel channel assembly has not damaged the tube sheet bore and that the tube sheet bore is ready for insertion of a new fuel channel assembly.

[0005] After the tube sheets are confirmed to be in suitable condition, the calandria tubes, pressure tubes, end fittings, and other components can be re-installed into the bores. For each fuel channel assembly, part of this process involves rolling the end of the calandria tube to the tube sheet of the calandria (e.g., using a deformable calandria insert), inserting an end fitting body into the bore, rolling the end of the pressure tube into the end fitting body, and inserting an end fitting liner into the end fitting.

[0006] The refurbishment of a nuclear reactor and retubing process may take up to two years to complete. A substantial portion of that time may be spent on the removal process, described above. Accordingly, there is a need for improved and faster removal of components of a fuel channel assembly, to reduce time for refurbishment of a nuclear reactor.SUMMARY

[0007] In one aspect, the disclosure describes a device for removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor, the rolled joint insert radially securing the calandria tube to the tube sheet. The device comprises: a body extending axially from a first end to a second end; a carriage coupled to the first end, the carriage configured to extend or retract the body into or out of a lattice site of the fuel channel assembly; a tool head having a distal end and a proximate end, the proximate end coupled to the second end of the body, the distal end having a surface configured to push an end of a pressure tube in the lattice site when the body is extended into the lattice site, surface positioned a distance radially from an longitudinal axis of the tool head to intersect the end of the pressure tube when the body is extended into the lattice site. The tool head comprises: a heater positioned at a distal end of the tool head for heating the rolled joint insert; a removal member for coupling to and removing the rolled joint insert from between the calandria tube and the tube sheet, the removal member positioned a distance inboard the heater; and at least one centering member configured to center the head in the lattice tube.

[0008] In an embodiment, the heater is an induction heating coil.

[0009] In an embodiment, the removal member is configured to radially extend and retract to engage the rolled joint insert, and wherein the removal member is configured to engage the rolled joint insert for removing rolled joint insert from the tube sheet. The removal member may be configured to move axially to into a chamber defined by tool head for receiving the rolled joint insert.

[0010] In an embodiment, the removal member has a datum member positioned to extend axially from the tool head and engage the rolled joint insert when the tool head is inserted into the lattice site.

[0011] In an embodiment, the device comprising a controller configured to: send data to the carriage to extend the body into the lattice site to push the pressure tube within the calandria tube away from the rolled joint insert. In an embodiment, the controller may be configured to: send data to the heater to heat the rolled joint insert to a first temperature; following the heating, allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature; send data to axially move the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert; send data to extend the removal member to radially engage and apply force against the rolled joint insert, where heating the rolled joint insert and the extending a removal member to radially engage and apply force against the rolled joint insert are performed by the tool head.

[0012] In an embodiment, the controller is configured to send data to a cooler to cool the rolled joint insert to the second temperature, wherein the cooling is by at least one of conduction by the cooler, convection by a cooling medium supplied by nozzles defined by the cooler, and radiation absorption by the cooler.

[0013] In an embodiment, the controller is in communication with a worktable and platform, where the device is positioned on the worktable, and the controller is configured to send data to the worktable and platform to move the device to a lattice site of the nuclear reactor comprising the fuel channel assembly. The controller may be configured to send data to the worktable to push the tool head against the pressure tube within the calandria tube away rom a rolled joint.

[0014] In an embodiment, the controller is configured to record a datum position; and move the tool head a predetermined distance from the datum position to a position where the heater is radially aligned with the roller joint insert.

[0015] In an embodiment, the at least one centering member comprises at least one of a plurality of rollers for centering the tool head in the lattice site, and a sleeve.

[0016] In another aspect, the disclosure describes a method of removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor, the rolled joint insert radially securing the calandria tube to the tube sheet. The method comprises: pushing a pressure tube within the calandria tube away from the rolled joint insert; heating the rolled joint insert to a first temperature; following the heating, allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature; axially moving the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert; extending a removal member to radially engage and apply force against the rolled joint insert. Heating the rolled joint insert and extending the removal member to radially engage and apply force against the rolled joint insert are performed by the tool head.

[0017] In an embodiment, the method comprises axially withdrawing the rolled joint insert from the tube sheet.

[0018] In an embodiment, the first temperature is between 800°C and 1500°C.

[0019] In an embodiment, the rolled joint insert reaches the first temperature in1.8 to 2.2 seconds.

[0020] In an embodiment, the second temperature is between 20°C and 180°C.

[0021] In an embodiment, the heating defines a heating region in which the tube sheet is not heated as the rolled joint insert is heated.

[0022] In an embodiment, the heating is by at least one of induction, conduction and convection.

[0023] In an embodiment, the cooling is by at least one of conduction, convection, and radiation.

[0024] In an embodiment, the method comprises depositing the withdrawn rolled joint insert into a containment flask.

[0025] In an embodiment, the method comprises: recording a datum position when removal member is positioned proximate to the rolled joint insert; and moving the tool head a predetermined distance from the datum position to the first position.

[0026] Embodiments may include combinations of the above features.

[0027] Further details of these and other aspects of the subject matter of this application will be apparent from the detailed description included below and the drawings.DESCRIPTION OF THE DRAWINGS

[0028] Reference is now made to the accompanying drawings, in which:

[0029] FIG. 1 is a perspective view of a CANDU™-type reactor.

[0030] FIG. 2A is a cutaway view of a CANDUTM-type nuclear reactor fuel channel assembly.

[0031] FIG. 2B is a perspective view of a platform, work table and a calandria tube insert removal tool adjacent a face of the CANDUTM-type reactor, according to an embodiment.

[0032] FIG. 3 is a perspective view of an example combined Calandria Tube Insert (CTI) release and removal tool.

[0033] FIG. 4 is a perspective view of a tool head of CTI release and removal tool 100 shown in FIG. 3.

[0034] FIG. 5 is a side elevation view of the CTI release and removal tool of FIG. 3 in an extended position at a target lattice site where the tool head is extended into the target lattice site.

[0035] FIG. 6 is a side cutaway view of a pressure tube and a closure plug at the opposite end of the target lattice site shown in FIG. 3.

[0036] FIG. 7 is a side cutaway view of a lattice site, a calandria tube insert, and tool head of FIG. 4 in a datum position. A fragmentary view of detail A is also shown.

[0037] FIG. 8 is a side cutaway view of a lattice site, a calandria tube insert, and tool head of FIG. 4 in a release position.

[0038] FIGs. 9A and 9B are side cutaway view of a lattice site and calandria tube insert showing tool head of FIG. 4 moved to a CTI cooling / removal position. FIG. 9A shows the tool head of FIG. 4 positioned to engage and apply a force to the CTI to release the CTI from the tubesheet, and FIG. 9B shows a removal member of the tool head moving the CTI into a chamber of the tool head.

[0039] FIG. 10 is a schematic view of an example method for removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor.

[0040] FIG. 11 is a schematic view of an example system for controlling a Calandria Tube Insert (CTI) release and removal tool.DETAILED DESCRIPTION

[0041] Before any embodiments are explained in detail, it is to be understood that the disclosure 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 disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.

[0042] DEFINITIONS

[0043] Although terms such as “maximize”, “minimize” and “optimize” may be used in the present disclosure, it should be understood that such terms may be used to refer to improvements, tuning and refinements which may not be strictly limited to maximal, minimal or optimal.

[0044] The term “connected” or "coupled to" may include both direct coupling (in which two elements that are coupled to each other and contact each other) and indirect coupling (in which at least one additional element is located between the two elements).

[0045] The term “substantially” as used herein may be applied to modify any quantitative representation which could permissibly vary without resulting in a change in the basic function to which it is related.

[0046] Terms such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0047] The singular forms "a," "an," and "the" include the plural reference unless the context clearly dictates otherwise. The term "and / or" means any one of the items, any combination of the items, or all of the items with which this term is associated.

[0048] The term "about" can refer to a variation of± 5%, ± 10%, ± 20%, or± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and / or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0049] Aspects of various embodiments are described through reference to the drawings.

[0050] 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. Although aspects are described with particular reference to the CANDUTM-type reactor 6 for convenience, the disclosure is not limited to CANDUTM-type reactors, and may be useful outside this particular field as well. A generally cylindrical vessel, known as the calandria vessel 10 of the CANDUTM-type reactor 6, contains a heavy-water moderator. The calandria vessel 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 (referred to herein as bores 19) 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 vessel 10 from the first end 22 to the second end 24.

[0051] As in the illustrated embodiment of Figs. 1 and 2A, 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 bores 19 (i.e. , in the tube sheet 18 and the end shield 64, respectively).

[0052] FIG. 2A is a cutaway view of one fuel channel assembly 28 of the reactor core illustrated in FIG. 1. As illustrated in FIG. 2A, 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 bores 19 in the tube sheets 18. In some embodiments, a rolled joint insert, for example calandria tube insert 34, is used to secure the CT 32 to the tube sheet 18 within the bores 19. 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. One or more annulus spacers or garter springs 48 are disposed between the CT 32 and PT 36. The annulus spacers 48 maintain the gap between the PT 36 and the corresponding CT 32, while allowing passage of annulus gas through and around the annulus spacers 48.

[0053] As also shown in FIG. 2A, each end of each fuel channel assembly 28 is provided with an end fitting assembly 50 located outside of the corresponding tube sheet 18. Each end fitting assembly 50 includes an end fitting body 57 and an end fitting liner 58. At the terminal end of each end fitting assembly 50 is a closure plug 52. Each end fitting assembly 50 also includes a feeder assembly 54. The feeder assemblies 54 feed reactor coolant into or remove reactor coolant from the PTs 36 via feeder tubes 59 (FIG. 1). 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, andthe feeder assembly 54 on the opposite end of the fuel channel assembly 28 acts as an outlet feeder. As shown in FIG. 2A, the feeder assemblies 54 can be attached to the end fitting assemblies 50 using a coupling assembly 56 including a number of screws, washers, seals, and / or other types of connectors. The lattice tube 65 (described above) encases the connection between the end fitting assembly 50 and the PT 36 containing the fuel assemblies 40. Shielding ball bearings 66 and cooling water surround the exterior of the lattice tubes 65, which provides additional radiation shielding.

[0054] A positioning hardware assembly 60 and bellows 62 are also coupled to each end fitting assembly 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 configuration that fixes the axial position, or an unlocked configuration. The positioning hardware assemblies 60 are also coupled to the end shield 64. The illustrated 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. Again, it should be understood that although a CANDUTM-type reactor is illustrated in FIGS. 1- 2A, the invention may also apply to other types of reactors, including reactors having components that are similar to those illustrated in FIGS. 1-2A.

[0055] Rolled joint inserts, e.g. calandria tube insert 34, may be used to secure the calandria tube 32 to the tube sheet 18 within the bores 19. During decommissioning, the rolled joint insert, may need to be removed such that the calandria tube may also be removed. Previously, a release of the Calandria Tube Insert (CTI) and removal of the CTI was conducted in series and separately. A CTI Release Tool would be mounted on a Fueling Machine Bridge (FMB) and has historically generated fuel channel accessibility issues. Coordination of movements between the Fuel Channel Platform (FCP), Heavy Work Table (HWT), FMB and FMB Carriage would be required for separate CTI Release and Removal operations. In comparison, a Combined CTI Release and Removal operation minimizes the interaction with the movement of the FCP, HWT and FMB. Combining a CTI release and removal tool may simplify coordination of movement between tools on the face of the Calandria andreduce accessibility issues to fuel channels of the calandria. Example combined CTI Release and Removal devices are described in International Patent Application No. PCT / CA2018 / 050770 (Published as WO2018232526A1) the entire contents of which are incorporated by reference herein.

[0056] FIG. 2B illustrates one embodiment of a heavy work table (“HWT”) 96 installed on a retube tooling platform (“RTP”) 95 adjacent the end 24 of the nuclear reactor. A similar HWT can be installed adjacent the end 22 of the nuclear reactor. The HWT 96 and any tools mounted on the HWT are controlled by a control station (not shown).

[0057] A calandria tube insert removal tool, CTI removal tool 100, is mounted on the HWT 96 and is positioned to remove calandria tube inserts 34 from tube sheet 18 at the end 24. As shown, CTI removal tool 100 may be positioned on a face of the nuclear reactor. The control of a position of the CTI removal tool 100 with respect to the end shield 64 and operation of the tool 100 may occur from the control station. Specifically, the operator can control the height of the RTP 95 along axis Y, the location of the CTI removal tool 100 on the HWT 96 along axis X and the pitch with respect to the end shield 64 to orient axis Z to be perpendicular to the end shield 64. In some embodiments, the height of RTP 95 may be adjusted by ball screws, for example, by way of one ball screw at each corner of RTP 95.

[0058] When the CTI removal tool 100 is aligned with the selected opening in the end shield 64, the operator can insert the CTI removal tool 100 into the appropriate fuel channel along axis Z. The CTI removal tool 100 can include any number of suitable sensors and / or cameras to verify that the CTI removal tool 100 is properly aligned with the respective opening in the end shield 64.

[0059] An induction heating power supply and control system 98 shown in FIG. 2B may be used to control heater 103 of CTI removal tool 100, described in more detail below.

[0060] FIG. 3 illustrates a perspective view of an example combined CTI release and removal tool 100. Combined CTI Release / Removal Tool 100 may be designed to combine the functions of release and removal of the CTI from the calandria tube sheet into a single tool head, as shown in FIG. 3. The CTI release and removaltool 100 may have a head 101 that pushes PT 36 further inboard. Shock heating of the CTI may be performed in a similar manner to the existing release tools using a coil with power provided via the CTI Release Load Matching Station (LMS) in carriage 102.After the CTI is removed using the removal member, CTI release and removal tool 100 may to deposit the CTI into a waste transfer flask.

[0061] FIG. 4 illustrates a perspective view of a tool head 101 of CTI release and removal tool 100 shown in FIG. 3. CTI release and removal tool 100 may comprise an heater 103, removal member 104, at least one centering member 105, and camera 106. In the embodiment of tool head 101 geometry shown in FIG. 4, heater 103 is positioned at a distal end of tool head 101 for heating a target CTI. Removal member 104 may be positioned centrally on tool heat 101 adjacent to heater 103 for removing CTI insert 34. In an embodiment, heater 103 may be an induction heating coil for heating calandria tube insert 34 without substantially heating the calandria tube sheet 18. Heating may be by a heating element that uses induction, conduction, or convection to increase the temperature of the target CTI. In an embodiment, the at least one centering member is configured to center the head in the lattice tube.Centering member 105 may comprise a plurality of rollers and / or a sleeve positioned to center tool head 101 within a lattice tube of the nuclear reactor. Centering member 105 may a perimeter of position tool head 101, including heating coil 103 and / or removal member 104 approximately an equal distance from an inner diameter of the lattice site and / or calandria tube insert.

[0062] FIG. 5 shows CTI release and removal tool 100 in at a target lattice site. CTI removal tool 100 may operate on a HWT at opposite end 22 of the nuclear reactor 6. After the closure plugs 52, positioning hardware assemblies 60, feeder assemblies 54, and the end fittings have been removed, a temporary shield plug (not shown) also referred to as a “thumbtack” 68, is inserted through end shield 64 into lattice tube 65. In some embodiments, temporary shield plug may be contained with a lattice sleeve assembly (“LSA”). In some embodiments, thumbtack 68 may include a sleeve, a temporary shield plug within the sleeve, and a flange. In some embodiments, bellows 62 may also be removed either before or after the temporary shield plug is inserted through end shield 64 into lattice tube 65.

[0063] In some embodiments, the CTI removal tool 100 is aligned with the end shield 64 via the thumbtack 68. The temporary shield plug of thumbtack 68 may be removed prior to the insertion of CTI removal tool 100.

[0064] During operation of CTI release and removal tool 100, tool 100 is inserted into a target lattice tube 65 and CT 32 as shown in FIG. 5. The CTI removal tool 100 may then be moved along the direction of arrow B-B to be inserted into the end shield 64. Any suitable means can be utilized to move the CTI removal tool 100 into and out of the tube sheet 18, such as a rigid push-pull chain or a servo rack drive. The position of the CTI removal tool 100 on the HWT 96 may be controlled by an operator via the control station. The CTI removal tool 100 may be precisely inserted to a desired depth as discussed in detail below.

[0065] When CTI release and removal tool 100 is inserted into the target lattice site and fuel channel, tool 100 may be centred in Calandria tube insert 34 by centering member 105 located on tool head 101. Centering member 105 may prevent damage to heater 103 due to misalignment. In an embodiment, centering member 105 may be roller and / or a sleeve positioned around a circumference of tool heat 101 and configured to extend into contact with in inner diameter of the target lattice site and / or fuel channel such that heat 103 and / or removal member 104 do not come into contact with lattice site and / or fuel channel as tool head 101 is inserted. Camera 106 may help locate and position tool 100 within CT 32. CTI release and removal tool 100 may be advanced into contact with an end of PT 36 pushing PT 36 within CT 32. Tool head 101 may push PT 36 inside and relative to CT 32 to allow tool head 101 to access a target CTI. In an embodiment, as shown in FIGs. 4 and 7, tool head 101 may comprise a surface 101a for engaging PT 36, the surface 101a positioned a distance radially from an longitudinal axis L of the tool head 101 configured to intersect an end of PT 36 when the tool head 101 is advanced within the lattice site and / or fuel channel. As shown in FIG. 6, on the opposite end of PT 36, the pushed PT 36 may maintain a gap 107 between the opposite end of PT 36 and thumbtack 68 at the opposite side of the target lattice site.

[0066] As shown in FIG. 7, CTI release and removal tool 100 may move tool head 101 to a datum position, e.g. where the datum member 104A on removal member 104 reaches an outboard end of CTI 34. Subsequently, CTI release and removal tool100 may move to a CTI Release position shown in FIG. 8. In an example, tool 100 may retract from the datum position a predetermined amount to align the heater 103 immediately adjacent to CTI 42 such that heater 103 is centered axially within the CTI 34. Heater 103 may then shock heat CTI 34.

[0067] In some embodiments, the calandria tube insert 34 is heated for a set time and / or to a set temperature. In some embodiments, heating may occur for a duration of between 1 and 10 seconds, in an example, 1 and 4 seconds, and in other embodiments more than 10 seconds. In some embodiments, heating may occur to reach a target temperature of between 800 and 1500 degrees Celsius of the calandria tube insert 34. In an example, the calandria tube insert 34 is heated to 1300 degrees Celsius in 1.8 to 2.2 seconds. One or more sensors, such as an optical sensor, a thermocouple or other suitable sensor, can be utilized to measure various features of the calandria tube insert 34.

[0068] In some embodiments, the calandria tube insert 34 is “shock heated”, for example, using induction heating, for a specific time and energy profile. The operator can use a timer or computer control to operate heater 103 for a set time. In some embodiments, control logic can be utilized to automatically actuate the heater 103 until a specific time period has elapsed and / or until the calandria tube insert 34 reaches a set temperature or a desired level of energy has been transmitted.

[0069] As shown in FIGs. 9A and 9B CTI release and removal tool 100 may move to a CTI Cooling / Removal position. In an embodiment, tool 100 may move to a CTI Cooling / Removal position for example about 60 seconds after heater 103 finishes shock heating CTI 34. After heating, CTI insert may shrink radially as it cools, thereby loosening it from the bore of Calandria tubesheet 18. As shown in FIG. 9A, tool head101 may be moved further inboard from CTI Datum position pushing PT 36 toward an opposite side of calandria 10. In an example, PT 36 is pushed only to an extent such that gap 107 is greater than or equal to a minimum clearance, e.g. of about 1 inch, from thumbtack 68 as shown in FIG. 6 to ensure that thumbtack 68 is not pushed out. To remove CTI 34, member 104 may be extended radially by with gradually increasing force until CTI 34 is released from tube sheet 18. Member 104 may then be moved axially to pull CTI 34 into tool 100. Tool 100 may comprise a chamber 108 for receiving CTI 34 and member 104. Once CTI 34 is secured, CTI release and removal tool 100may be withdrawn from the lattice site to its home position illustrated in FIG. 5 where CTI 34 may be dropped into a waste transfer flask (not shown).

[0070] In an embodiment, the cooling section of CTI release and removal tool 100 includes at least one cooling element 109 ( “cooler”) that cools the calandria tube insert 34 to a desired temperature by at least one of conduction and convection. Cooling element 109 may be in fluid communication with a fan, pump, or pressurized system (not shown) which supplies a cooling medium to cooler 109. In some embodiments, the cooling medium may be at least one of liquid nitrogen, a cool air jet, cooling coils, an alcohol bath, liquid lead, helium or dry ice, etc., that contacts the calandria tube insert 34 either directly, for example, directed by nozzles 109 on CTI removal tool 100, or through a barrier. In some embodiments, the cooling element 109 can include a heat pipe. For example, the cooling medium can circulate within heat pipe of the cooling element and be surrounded by a thermally conductive material, such as metal, and the thermally conductive material of the heat pipe can contact the calandria tube insert 34 to actively cool the calandria tube insert 34. In some embodiments, the cooling section may include a radiator to absorb heat energy from calandria tube insert 34, for example, as a black body heat sink. Heat pipes and blackbodied heat sinks may be advantageous as they do not blow air which may disturb and / or mobilize radioactive debris. In some embodiments, the removal member 104 may comprise the cooling element. In the example shown in FIG. 9A, the cooling element comprises nozzles 109 for directing a cooling medium, e.g. air, from a blower (not shown) at the calandria tube insert 34. However, removal member 104 may also comprise a heat pipe and / or black-bodied heat sink for receiving heat energy from calandria tube insert 34.

[0071] In some embodiments, as shown in FIG. 9A and 9B, removal member 104 may extend to abut the calandria tube insert 34 to perform cooling of the calandria tube insert 34. In some embodiments, the removal member contacts the calandria tube insert 34 around at least a portion of the inner diameter of the calandria tube insert 34. In some embodiments, the removal member contacts a majority of the inner diameter of the calandria tube insert 34. In an embodiment, cooling element 109 of removal member 104 may comprise nozzles 109a to direct a cooling medium, e.g. air onto the calandria tube insert 34. In another embodiment, cooler 109 may be cooled, e.g. by aheat pipe and / or black-bodied heat sink, such that removal member 104 will cool calandria tube insert 34 when engaged with calandria tube insert 34.

[0072] FIG. 10 shows a schematic diagram illustrating a method 1000 for removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor. The rolled joint insert may be radially securing the calandria tube to the tube sheet.

[0073] At 1002, the method comprises pushing a pressure tube within the calandria tube away from the rolled joint insert.

[0074] At 1004, the method comprises heating the rolled joint insert to a first temperature. In an embodiment, the first temperature is between 800°C and 1500°C. In an example, the rolled joint insert may reach the first temperature in 1.8 to 2.2 seconds. Heating the rolled joint insert may be in a defined heating region in which the tube sheet is not heated, or heated a lower rate, in comparison to the rolled joint insert. Non limiting example of heating may be performed at least one of induction, conduction and convection.

[0075] At 1006, following the heating, the method comprises allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature. In an embodiment, the second temperature is between 20°C and 180°C. Non-limiting example of cooling may be by at least one of conduction and convection.

[0076] At 1008, the method comprises axially moving the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert.

[0077] At 1010, the method comprises extending a removal member to radially engage and apply force against the rolled joint insert. Heating the rolled joint insert and the extending a removal member to radially engage and apply force against the rolled joint insert are performed by the tool head.

[0078] In an embodiment, method 1000 comprises axially withdrawing the rolled joint insert from the tube sheet.

[0079] In another embodiment, method 1000 comprises depositing the withdrawn rolled joint insert into a containment flask.

[0080] In another embodiment, method 1000 comprises recording a datum position when removal member is positioned proximate to the rolled joint insert; and moving the tool head a predetermined distance from the datum position to the first position.

[0081] CONTROLLER

[0082] FIG. 11 shows a generalized schematic view of example system 2000 for controlling a cutting tool for segmenting a calandria vessel. System 2000 may comprise controller 2001, described herein. Controller 2001 includes a processor 2002 configured to implement processor readable instructions that, when executed, configure the processor 2002 to conduct operations described herein. The processor 2002 may be a microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, a programmable read-only memory (PROM), or combinations thereof. Controller 2001 may include a communication interface 2004 to communicate with other computing or sensor devices, to access or connect to network resources, or to perform other computing applications by connecting to a network (or multiple networks) capable of carrying data. In some examples, the communication interface 2004 may include one or more busses, interconnects, wires, circuits, and / or any other connection and / or control circuit, or combination thereof. The communication interface 2004 may provide an interface for communicating data between the system 2000 and a display 2015.

[0083] Controller 2001 may also comprise connections for communicating with any of CTI Release / Removal tool 100, worktable 96, platform 95, removal member 104, heater 103, and / or camera 106 according to this disclosure to transmit setpoint(s) or receive data such as position, orientation, and CTI Release / Removal tool status, among other data.

[0084] Controller 2001 may comprise a sensor 2010 and connection(s) for monitoring position, orientation, and / or CTI Release / Removal tool status.

[0085] Controller 2001 may be coupled to a data system 2014 for storing system data and / or may be configured to communicate with cloud services such as iCloud, Dropbox, Google clouds, or any other digital data servers. Data system 2014 may also comprises a universal asynchronous receiver-transmitter (UART) to allowcommunication with other devices, e.g. a smartphone or a computer, for transmitting data for analysis and / or storage. LIART may include or be coupled to a wireless transceiver for wireless communication with such other devices, e.g., by way of infrared, Bluetooth, Wi-Fi, or the like. Network 2500 may include any wired or wireless communication path, such as an electrical circuit. In some embodiments, the network 2500 may include one or more busses, interconnects, wires, circuits, and / or any other connection and / or control circuit, or a combination thereof. In some embodiments, the network 2500 may include a wired or a wireless wide area network (WAN), local area network (LAN), a combination thereof, or the like. In some embodiments, the network 2500 may include a Bluetooth® network, a Bluetooth® low energy network, a short- range communication network, or the like.

[0086] Controller 2001 may include memory 2006. The memory 2006 may include one or a combination of computer memory, such as static random-access memory (SRAM), random-access memory (RAM), read-only memory (ROM), electro- optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

[0087] The memory 2006 may store an application 2012 including processor readable instructions for conducting operations described herein. In some examples, the application 2012 may include operations for controlling a CTI Release / Removal tool according this disclosure.

[0088] In an embodiment, application 2012 may include operations for moving a worktable and platform to position CTI Release and Removal Tool for insertion into a lattice site of a nuclear reactor. Application 2012 may also include operation for moving the worktable toward an end shield of the nuclear reactor to insert the CTI release and removal tool into a lattice tube.

[0089] Application 2012 may also include operations for pushing a pressure tube within a calandria tube away from a rolled joint insert, e.g. by moving the worktable and CTI release and removal tool thereon toward the end shield to move an end of the CTI release and removal tool into contact with the pressure tube. CTI release and removal tool may also be configured to move independently of the worktable, and mayextend the head of the CTI release and removal tool into contact with the pressure tube to move the pressure tube, within the calandria tube, away from the calandria tube insert. In an embodiment, application 2012 may include operations for sending data to the carriage of the CTI Release and Removal Tool to extend the body of the CTI Release and Removal Tool into the lattice site to push the pressure tube within the calandria tube away from the rolled joint insert.

[0090] In another embodiment, Application 2012 may also include operations for heating the rolled joint insert to a first temperature. In an example, the first temperature is between 800°C and 1500°C. The rolled joint insert may reach the first temperature in 1.8 to 2.2 seconds. Heating may be defined in a heating region in which the tube sheet is not heated as the rolled joint insert is heated. Heat may be applied by at least one of induction, conduction and convection.

[0091] Application 2012 may also include operations for, following the heating, allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature. In an example, the second temperature is between 20°C and 180°C. Cooling may be by at least one of conduction and convection.

[0092] Application 2012 may also include operations for axially moving the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert.

[0093] Application 2012 may also include operations for extending a removal jaw member to radially engage and apply force against the rolled joint insert. In an embodiment, application 2012 may also include operations for axially withdrawing the rolled joint insert from the tube sheet. Heating the rolled joint insert and the extending a removal member to radially engage and apply force against the rolled joint insert are both performed by the tool head.

[0094] In an embodiment, application 2012 may also include operations for depositing the withdrawn rolled joint insert into a containment flask.

[0095] In an embodiment, application 2012 may also include operations for recording a datum position when removal member is positioned proximate to the rolledjoint insert; and moving the tool head a predetermined distance from the datum position to the first position. The datum position may also be recorded when any other component of the tool head is positioned adjacent a component of the nuclear reactor, e.g. when the camera at the end of the tool heat is initially inserted into the lattice tube.

[0096] Alternate embodiments

[0097] The above description is meant to be exemplary only, and one skilled in the relevant arts will recognize that changes may be made to the embodiments described without departing from the scope of the invention disclosed. The present disclosure may be embodied in other specific forms without departing from the subject matter of the claims. The present disclosure is intended to cover and embrace all suitable changes in technology. Modifications which fall within the scope of the present invention will be apparent to those skilled in the art, in light of a review of this disclosure, and such modifications are intended to fall within the appended claims. Also, the scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.

[0098] As can be understood, the detailed embodiments described above and illustrated are intended to be examples only. The invention is defined by the appended claims.

[0099] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations, unless such a limitation is explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.

Claims

CLAIMSWHAT IS CLAIMED IS:

1. A device for removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor, the rolled joint insert radially securing the calandria tube to the tube sheet, the device comprising: a body extending axially from a first end to a second end; a carriage coupled to the first end, the carriage configured to extend or retract the body into or out of a lattice site of the fuel channel assembly; a tool head having a distal end and a proximate end, the proximate end coupled to the second end of the body, the distal end having a surface configured to push an end of a pressure tube in the lattice site when the body is extended into the lattice site, the surface positioned a distance radially from an longitudinal axis of the tool head to intersect the end of the pressure tube when the body is extended into the lattice site, the tool head comprising: a heater positioned at a distal end of the tool head for heating the rolled joint insert; a removal member for coupling to and removing the rolled joint insert from between the calandria tube and the tube sheet, the removal member positioned a distance inboard the heater; and at least one centering member configured to center the head in the lattice tube.

2. The device of claim 1 , wherein the heater is an induction heating coil.

3. The device of claim 1 , wherein the removal member is configured to radially extend and retract to engage the rolled joint insert, and wherein the removal member is configured to engage the rolled joint insert for removing rolled joint insert from the tube sheet.

4. The device of claim 3, wherein the removal member is configured to move axially to into a chamber defined by tool head for receiving the rolled joint insert.

5. The device of any one of claims 1-4, wherein the removal member has a datum member positioned to extend axially from the tool head and engage the rolled joint insert when the tool head is inserted into the lattice site.

6. The device of any one of claims 1-5, comprising a controller configured to: send data to the carriage to extend the body into the lattice site to push the pressure tube within the calandria tube away from the rolled joint insert.

7. The device of claim 6, wherein the controller is configured to: send data to the heater to heat the rolled joint insert to a first temperature; following the heating, allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature; send data to axially move the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert; send data to extend the removal member to radially engage and apply force against the rolled joint insert; wherein the heating the rolled joint insert and the extending a removal member to radially engage and apply force against the rolled joint insert are performed by the tool head.

8. The device of claim 7, wherein the controller is configured to send data to a cooler to cool the rolled joint insert to the second temperature, wherein the cooling is by at least one of conduction by the cooler, convection by a cooling medium supplied by nozzles defined by the cooler, and radiation absorption by the cooler.

9. The device of any one of claims 6-8 wherein the controller is in communication with a worktable and platform, wherein the device is positioned on the worktable, and wherein the controller is configured to send data to the worktable and platform to move the device to a lattice site of the nuclear reactor comprising the fuel channel assembly.

10. The device of claim 9, wherein the controller is configured to send data to the worktable to push the tool head against the pressure tube within the calandria tube away rom a rolled joint.

11. The device of claim 9 or 10, wherein the controller is configured to record a datum position; and move the tool head a predetermined distance from the datum position to a position where the heater is radially aligned with the roller joint insert.

12. The device of any one of claims 1-11, wherein the at least one centering member comprises at least one of a plurality of rollers for centering the tool head in the lattice site, and a sleeve.

13. A method of removing a rolled joint insert from between a calandria tube of a fuel channel assembly of a nuclear reactor and a tube sheet of the nuclear reactor, the rolled joint insert radially securing the calandria tube to the tube sheet, the method comprising: pushing a pressure tube within the calandria tube away from the rolled joint insert; heating the rolled joint insert to a first temperature; following the heating, allowing the rolled joint insert to cool to a second temperature, the second temperature less than the first temperature; axially moving the tool head along a defined axis from a first position of the tool head when heating the rolled joint insert to a second position where the removal member is radially aligned with the rolled joint insert; extending the removal member to radially engage and apply force against the rolled joint insert; wherein the heating the rolled joint insert and the extending the removal member to radially engage and apply force against the rolled joint insert are performed by the tool head.

14. The method of claim 13, comprising axially withdrawing the rolled joint insert from the tube sheet.

15. The method of claim 13 or claim 14, wherein the first temperature is between 800°C and 1500°C.

16. The method of any one of claims 13-15, wherein the rolled joint insert reaches the first temperature in 1 .8 to 2.2 seconds.

17. The method of any one of claims 13-16, wherein the second temperature is between 20°C and 180°C.

18. The method of any one of claims 13-17, wherein the heating defines a heating region in which the tube sheet is not heated as the rolled joint insert is heated.

19. The method of any one of claims 13-18, wherein the heating is by at least one of induction, conduction and convection.

20. The method of any one of claims 13-19, wherein the cooling is by at least one of conduction, convection, and radiation.21 . The method of any one of claims 13-20, comprising depositing the withdrawn rolled joint insert into a containment flask.

22. The method of any one of claims 13-21 , comprising: recording a datum position when removal member is positioned proximate to the rolled joint insert; and moving the tool head a predetermined distance from the datum position to the first position.

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