CA2766459A1

CA2766459A1 - Calandria tube, pressure tube, and annulus spacers removal apparatus and method for nuclear reactor retubing

Info

Publication number: CA2766459A1
Application number: CA2766459A
Authority: CA
Inventors: Bryan John Murdoch; George Solti; Frank Kamler; Marcos Ara Montrichard
Original assignee: Atomic Energy of Canada Ltd AECL
Current assignee: Atomic Energy of Canada Ltd AECL
Priority date: 2011-01-17
Filing date: 2012-01-16
Publication date: 2012-07-17
Anticipated expiration: 2032-01-16
Also published as: CA2766459C

Abstract

Methods, tools, and systems for removing a calandria tube and a pressure tube from a nuclear reactor. One method includes gripping at least a portion of a first diameter of a calandria tube contained at a lattice site with a guide tool, wherein the calandria tube includes a pressure tube rotated from an operational position to a removal position, and gripping at least a portion of a second diameter of the calandria tube with a retrieval tool. The method also includes pulling the calandria tube with the retrieval tool to remove the calandria tube from at least one tube sheet and advancing the calandria tube and the rotated pressure tube as a package with the retrieval tool and the guide tool across at least a portion of the calandria toward a receiving end of the reactor. The method further includes releasing the guide tool from the first diameter of the calandria tube, and retracting the guide tool from the lattice site at the pushing end of the reactor.

Description

Attorney Docket No. 027813-9038-CA00 CALANDRIA TUBE, PRESSURE TUBE, AND ANNULUS SPACERS REMOVAL
APPARATUS AND METHOD FOR NUCLEAR REACTOR RETUBING
RELATED APPLICATIONS

[0001] The present application claims priority to U.S. Provisional Application No.
61/433,349 titled "NUCLEAR REACTOR PRESSURE TUBE SEVERING TOOL AND
METHOD" filed January 17, 2011, and U.S. Provisional Application No.
61/433,479 titled "CALANDRIA TUBE, PRESSURE TUBE, AND ANNULUS SPACERS REMOVAL
APPARATUS AND METHOD FOR NUCLEAR REACTOR RETUBING" filed January 17, 2011, the entire contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to methods and systems for retubing nuclear reactors.
SUMMARY

[0003] A nuclear reactor has a limited life of operation. For example, second generation CANDU-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 CANDU-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] Therefore, embodiments of the present invention provide methods and systems for retubing a nuclear reactor. The retubing process includes a removal process of various reactor components. During the removal process, the existing calandria tube, pressure tube, and annulus spacers that separate the pressure tube and the calandria tube can be removed as a package. To create the removable package, the pressure tube is severed and rotated while contained inside the calandria tube. Rotating the pressure tube counters the sag typically found in existing calandria Attorney Docket No. 027813-9038-CAOO

and pressure tubes and applies a constraining load to the annulus spacers.
Thus the result is a straighter package with constrained components that is easier to remove from the reactor. Also, by rotating the pressure tube as just described, the annulus spacers are better contained within the package during removal, which allows for easier handling and control. This procedure eliminates one removal step (i.e., separately removing the pressure tube from the calandria tube), and allows two components to be transported and disposed of as one package.

[0005] Accordingly, one embodiment of the invention provides a method of removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor. The method includes gripping, with a guide tool advanced into the lattice site from a pushing end of the reactor, at least a portion of a first diameter of a calandria tube contained in the lattice site, wherein the calandria tube includes a pressure tube rotated from an operational position to a removal position, and gripping, with a retrieval tool advanced into the lattice site from a receiving end of the reactor, at least a portion of a second diameter of the calandria tube. The method further includes pulling, with the retrieval tool, the calandria tube to remove the calandria tube from at least one tube sheet, and advancing, with the retrieval tool and the guide tool, the calandria tube and the rotated pressure tube as a package across at least a portion of the calandria toward the receiving end of the reactor. In addition, the method includes releasing the guide tool from the first diameter of the calandria tube, and retracting the guide tool from the lattice site at the pushing end of the reactor.

[0006] Another embodiment of the invention provides a tool for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor. The tool includes a retrieval tool configured to be positioned within a diameter of a calandria tube contained in a lattice site, the calandria tube including a pressure tube rotated from an operational position to a removal position. The tool also includes at least one gripper positioned on the retrieval tool configured to grip at least a portion of the diameter of the calandria tube. In addition, the tool includes a puller positioned on the retrieval tool and configured to pull the calandria tube free from at least one tube sheet. The retrieval tool is configured to move the calandria tube and the rotated pressure tube as a package across a calandria.

Attorney Docket No. 027813-9038-CAOO

[0007] Still another embodiment of the invention provides a tool for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor. The tool includes a guide tool configured to be positioned within a diameter of a calandria tube contained in a lattice site, the calandria tube including a pressure tube rotated from an operational position to a removal position. The tool also includes at least one gripper positioned on the guide tool, the at least one gripper configured to grip at least a portion of the diameter of the calandria tube, and a pusher positioned on the guide tool configured to push the calandria tube and the rotated pressure tube as a package across a calandria.

[0008] Furthermore, another embodiment of the invention provides a system for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor. The system includes a retrieval tool and a guide tool. The retrieval tool is configured to be advanced into a lattice site including a calandria tube and a pressure tube rotated from an operational position to a removal position from a receiving end of the reactor until the retrieval tool is positioned within a first diameter of the calandria tube, to grip at least a portion of the first diameter of the calandria tube, to pull the calandria tube to release the calandria tube from at least one tube sheet, and to move the calandria tube and the rotated pressure tube as a package across a calandria and out of the lattice site at the receiving end of the reactor. The guide tool is configured to be advanced into the lattice site from a pushing end of the reactor until the guide tool is positioned within a second diameter of the calandria tube, to grip at least a portion of the second diameter of the calandria tube, and to guide the calandria tube and the rotated pressure tube as a package across at least a portion the calandria toward the receiving end of the reactor.

[0009] Still another embodiment of the invention provides a method of removing a calandria tube, a pressure tube, and a plurality of annulus spacers from a calandria of a nuclear reactor during retubing of the reactor. The method includes gripping at least a portion of a first diameter of the pressure tube from a pushing end of the reactor, advancing the pressure tube across the calandria to a receiving end of the reactor and into a flask, and sweeping the plurality of annulus spacers from within the calandria tube. The method also includes gripping at least a portion of a first diameter of the calandria tube from a pushing end of the reactor, gripping at least a portion Attorney Docket No. 027813-9038-CA00 of a second diameter of the calandria tube from a receiving end of the reactor, and advancing the calandria tube across the calandria to the receiving end of the reactor.

[0010] Other aspects of the present invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 is a perspective view of a reactor core of a CANDU-type nuclear reactor.

[0012] FIG. 2 is a cut-away view of a CANDU-type nuclear reactor fuel channel assembly.

[0013] FIGS. 3 and 4 are perspective views of a pressure tube severing tool according to embodiments of the present invention.

[0014] FIG. 5 illustrates a cutting head of the pressure tube severing tool of FIGS. 3 and 4 according to an embodiment of the present invention, shown with cutting wheels extended.

[0015] FIG. 6 is a flow chart illustrating a method for severing a pressure tube using the pressure tube severing tool of FIGS. 3 and 4 according to an embodiment of the present invention.

[0016] FIG. 7 is a cut-away view of the cutting head of the pressure tube severing tool of FIG. 3 inserted inside a pressure tube.

[0017] FIG. 8 is a perspective view of a retrieval tool according to an embodiment of the invention.

[0018] FIG. 9 is a perspective view of a receiving guide sleeve according to an embodiment of the invention.

[0019] FIG. 10 is a perspective view of a pushing guide sleeve according to an embodiment of the invention.

[0020] FIG. 11 is a perspective view of a guide tool according to an embodiment of the invention.

Attorney Docket No. 027813-9038-CAOO

[0021] FIG. 12 is a perspective view of receiving tooling installed at a receiving end of a reactor.

[0022] FIG. 13 is a perspective view of guide tooling installed at a pushing end of a reactor.

[0023] FIGS. 14 and 15 are flow charts illustrating a removal process for removing a calandria tube, a pressure tube, and annulus spacers as a single package according to an embodiment of the invention.

[0024] FIG. 16 is a cut-away view of the guide tool of FIG. 11 on the pushing end of the reactor, shown gripping a diameter of a calandria tube.

[0025] FIG. 17 is a cut-away view of the retrieval tool of FIG. 8 on the receiving end of the reactor, shown gripping a diameter of the calandria tube.

[0026] FIG. 18 is a cut-away view of the retrieval tool of FIG. 8 on the receiving end of the reactor, shown performing a first pull of a calandria tube.

[0027] FIG. 19 is a cut-away view of the guide tool of FIG. 11 on the pushing end of the reactor after the first pull of the calandria tube.

[0028] FIG. 20 is a cut-away view of the retrieval tool of FIG. 8 on the receiving end of the reactor moving the calandria tube through the receiving guide sleeve of FIG.
9.

[0029] FIG. 21 is a cut-away view of the guide tool of FIG. 11 on the pushing end of the reactor, shown after the calandria tube is moved through the receiving guide sleeve of FIG. 9.

[0030] FIG. 22 is a cut-away view of the guide tool of FIG. 11 on the receiving end of the reactor, shown before a second pull of the calandria tube.

[0031] FIG. 23 is a cut-away view of the retrieval tool of FIG. 8 on the receiving end of the reactor, shown before the second pull of the calandria tube.

[0032] FIG. 24 is a cut-away view of the retrieval tool of FIG. 8 on the receiving end of the reactor, shown after the second pull of the calandria tube.

Attorney Docket No. 027813-9038-CA00

[0033] FIG. 25 is a cut-away view of the guide tool of FIG. 11 on the pushing end of the reactor, shown after the second pull of the calandria tube.

[0034] FIG. 26 is a cut-away view of the guide tool of FIG. 11 on the pushing end of the reactor, shown retracting from the calandria tube.

DETAILED DESCRIPTION

[0035] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the methods and processes described herein can be performed in various orders. Therefore, unless otherwise indicated herein, no required order is to be implied from the order in which elements, steps, or limitations are presented in the detailed description or claims of the present application. Also unless otherwise indicated herein, the method and process steps described herein can be combined into fewer steps or separated into additional steps.

[0036] FIG. 1 is a perspective of a reactor core of a CANDU-type reactor 6.
The reactor core is typically contained within a vault that is sealed with an air lock for radiation control and shielding. A generally cylindrical vessel, known as a calandria 10, contains a heavy-water moderator. The calandria 10 has an annular shell 14 and a tube sheet 18 at a first end 22 and a second end 24. The tube sheets 18 include a plurality of bores that accept a fuel channel assembly 28. As shown in FIG. 1, a number of fuel channel assemblies 28 pass through the tube sheets 18 of calandria 10 from the first end 22 to the second end 24.

[0037] FIG. 2 is a cut-away view of the fuel channel assembly 28. As illustrated in FIG. 2, each fuel channel assembly 28 is surrounded by a calandria tube ("CT") 32. The CT 32 forms a first boundary between the heavy water moderator of the calandria 10 and the fuel bundles or assemblies 40. The CTs 32 are positioned in the bores on the tube sheet 18. A
CT rolled joint insert 34 within each bore is used to secure the CT 32 to the tube sheet 18.

Attorney Docket No. 027813-903 8-CAOO

[0038) A pressure tube ("PT") 36 forms an inner wall of the fuel channel assembly 28. The PT 36 provides a conduit for reactor coolant and the fuel bundles or assemblies 40. The PT 36, for example, generally holds two or more fuel assemblies 40 and acts as a conduit for reactor coolant that passes through each fuel assembly 40. An annulus space 44 is defined by a gap between the PT 36 and the CT 32. The annulus space 44 is normally filled with a circulating gas, such as dry carbon dioxide, helium, nitrogen, air, or mixtures thereof.
The annulus space 44 and circulating gas are part of an annulus gas system. The annulus gas system can serve two functions. First, a gas boundary between the CT 32 and PT 36 provides thermal insulation between hot reactor coolant and fuel within the PTs 36 and the relatively cool CTs 32. Second, the annulus gas system provides an indication of a leaking CT 32 or PT 36 via the presence of moisture, deuterium, or both in the annulus gas.

[0039] An annulus spacer or garter spring 48 is disposed between the CT 32 and PT 36. The annulus spacer 48 maintains the annulus space 44 between the PT 36 and the corresponding CT
32, while allowing the passage of the annulus gas through and around the annulus spacer 48.
Maintaining the annulus space 44 helps ensure safe and efficient long-term operation of the reactor 6.

[0040] As also shown in FIG. 2, an end fitting 50 is attached at the fuel channel assembly 28 outside of the tube sheet 18 at each end 22, 24. At the front of each end fitting 50 is a closure plug 52. Each end fitting 50 also includes a feeder assembly 54. The feeder assemblies 54 feed reactor coolant into or remove reactor coolant from the PTs 36. In particular, for a single fuel channel assembly 28, the feeder assembly 54 on one end of the fuel channel assembly 28 acts as an inlet feeder, and the feeder assembly 54 on the opposite end of the fuel channel assembly 28 acts as an outlet feeder. As shown in FIG. 2, the feeder assemblies 54 can be attached to the end fitting 50 using a coupling assembly 56 including a number of screws, washers, seals, and/or other types of connectors.

[0041] Coolant from the inlet feeder assembly flows along an annular channel of the end fitting 50 until it reaches a shield plug 58. The shield plug 58 is contained inside the end fitting 50 and provides radiation shielding. The shield plug 58 also includes a number of openings that allow the coolant provided by the inlet feeder assembly to enter an end of a PT 36. A shield plug Attorney Docket No. 027813-9038-CA00 58 located within the end fitting 50 at the other end of the fuel channel assembly 28 includes similar openings that allow coolant passing through the PT 36 to exit the PT
36 and flow to the outlet feeder assembly 54 through a perimeter channel of another end fitting 50 at the opposite face of the reactor 6. As shown in FIG. 1, feeder tubes 59 are connected to the feeder assemblies 54 that carry coolant to or away from the reactor 6.

[0042] Returning to FIG. 2, a positioning hardware assembly 60 and bellows 62 are also coupled to each end fitting 50. The bellows 62 allows the fuel channel assemblies 28 to move axially. The positioning hardware assemblies 60 are used to set an end of a fuel channel assembly 28 in either a locked or an unlocked position. In a locked position, the end of the fuel channel assembly 28 is held stationary. In an unlocked position, the end of the fuel channel assembly 28 is allowed to move. A tool can be used with the positioning hardware assemblies 60 to switch the position of a particular fuel channel assembly 28.

[0043] The positioning hardware assemblies 60 are also coupled to an end shield 64. The end shields 64 provide additional radiation shielding. Positioned between the tube sheet 18 and the end shield 64 is a lattice sleeve or tube 65. The lattice tube 65 encases the connection between the end fitting 50 and the PT 36 containing the fuel assemblies 40.
Shielding ball bearings 66 and cooling water surround the exterior the lattice tubes 65, which provides additional radiation shielding.

[0044] It should be understood that although a CANDU-type reactor is illustrated in FIGS. 1 and 2, 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 and 2.

[0045] As described above, the reactor 6 can be retubed to extend its useful life. The retube process can include various steps and series of steps. For example, to prepare for retubing, the reactor 6 can be shut down and the reactor vault can be prepared for retubing.
A variety of material-handling equipment, tools, supports, and systems can also be installed and implemented to aid the retubing process. In some embodiments, a retube tool platform ("RTP") is installed.
The RTP is an adjustable platform upon which much of the fuel channel removal operations are performed. One or more heavy work tables ("HWTs") can be installed and mounted on the RTP, which can serve as the basis for tool delivery during the removal process. The HWTs provide a Attorney Docket No. 027813-9038-CA00 platform that supports retubing equipment. Various control and observation systems can also be installed and commissioned at this point in the process, such as a retube control center ("RCC"), a vault observation system ("VOS"), and a vault communication system ("VCS").

[0046] Once the reactor 6 is prepared for retubing, various initial components can be removed from the reactor 6, such as the closure plugs 52 and the positioning hardware assemblies 60. The feeder assemblies 54 can also be disconnected from the end fittings 50.

[0047] Also, in preparation for removing the fuel channel assemblies 28, the bellows 62 and the PTs 36 can be severed. A pressure tube severing tool ("PTST") 70 is illustrated in FIGS. 3 and 4. The PTST 70 can be installed adjacent a reactor face on a HWT 72. The HWT 72 carries and supports the PTST 70 as the PTST 70 is moved from lattice site to lattice site across the face of the calandria 10. The HWT 72 is laterally movable in an x direction (e.g., upon rails) by one or more drives at a common elevation across the face of the calandria 10. In some embodiments, the HWT 72 can also be vertically movable in a y and/or a z direction by one or more drives. In other embodiments, however, the HWT 72 is movable in an x direction, the HWT
72 is mounted upon a RTP assembled in front of the reactor face that is movable in the y direction, and additional tooling and systems (e.g., a removal pallet system) mounted on top of the HWT 72 are movable in the z direction.

[0048] The PTST 70 can include a cutting head 74 (see FIG. 5). The cutting head 74 can include a chipless tube cutter that minimizes the creation of loose contaminated debris during the severing, which can be difficult to control and clean. In some embodiments, the cutting head 74 contains a plurality of (e.g., approximately three) cutting wheels 75. A drive shaft 76 transmits rotational energy to the cutting head 74, while a second shaft 77 (e.g., located inside the drive shaft 76) can control extension of the cutting wheels 75 (see FIG. 7). This configuration can allow for dependant control of the cutting parameters (e.g., rotation and extension of the cutting wheels 75 are dependent on the same drive shaft 76). Due to the possible hardened state of the PT 36, cutting speeds and forces can be controlled to avoid a ragged cut edge.

[0049] In some embodiments, the cutting head 74 includes threads that connect to the PTST
70 using a right-handed thread direction. The threads create a self-tightening relationship between the cutting head 74 and the PTST 70 as the cutting head 74 is rotated to sever the PT 36.

Attorney Docket No. 027813-9038-CA00

[0050] FIG. 6 is a flow chart illustrating a method 80 of severing a PT 36 using the PTST 70 according to one embodiment of the invention. As shown in FIG. 6, the method 80 includes removing the shield plug 58 from a lattice site (at 81), aligning the PTST 70 with the lattice site (at 82), and inserting the PTST 70 into the lattice site (at 83). In some embodiments, the PTST
70 can be physically attached to the reactor 6 after being inserted into the lattice site. For example, clamps can be used to attach the PTST 70 to other components of the reactor 6 for stability (e.g., the end fittings 50).

[0051] FIG. 7 illustrates the PTST 70 inserted into a lattice site. In some embodiments, the PTST 70 is inserted into the lattice site until the cutting head 74 reaches a desired distance within the PT 36. For example, the cutting head 74 (i.e., the cutting wheels 75 located on the cutting head 74) can be positioned approximately 24.0 inches from the end of the PT
36. Severing the PT 36 at this location allows access to the CT 32 separate from the PT 36 (i.e., the CT 32 is longer than the severed PT 36 contained within the CT 32). In addition, this severing location limits deformation of the PT during the cutting process, which eliminates the ligament effect sometimes seen during PT cutting. Furthermore, severing the PT 36 at this location also contains all of the annulus spacers 48 contained in the fuel channel assembly 28.
Therefore, the location of the PT cut may vary based on the location and configuration of the annulus spacers 48 in a particular reactor.

[0052] With the cutting head 74 of the PTST 70 inserted into the lattice site within the PT 36 at the desired position (e.g., approximately 24.0 inches from the end of the PT 36), the cutting wheels 75 can be extended using the second shaft 77 to engage the wheels 75 with inside diameter of the PT 36 (at 84). Extending the cutting wheels 75 can plunge the sharp cutting wheels 75 into the PT 36. With the cutting wheels 75 engaged with the PT 36, the cutting head 74 is rotated (e.g., via the drive shaft 76) (at 85). As the cutting head 74 rotates, the cutting wheels 75 are rotated and sever the PT 36.

[0053] In some embodiments, after the PT 36 is severed from the end fitting 50, the PT 36 can be rotated with respect to the CT 32 from an operational position to a removal position to prepare the PT 36 for removal with the CT 32 as described below (at 86). In some cases, the removal position is approximately 180 degrees from the operational position, although, other Attorney Docket No. 027813-903 8-CA00 degrees of rotation can be performed to achieve similar results. Rotating the PT 36 to the removal position can turn the bottom surface of the PT 36 into the top surface, which helps maintain the annulus spacers 48 captive, and reduces the overall bow in the CT/PT combination.
For example, PTs 36 and CTs 32 can sag of as much as four inches over time.
These sags, however, can be effectively cancelled by rotating the PT 36 approximately 180 degrees within the CT 32, which creates a tube package that is significantly straighter than either of the individual tubes (the rotation of the sagged PT relative to the sagged CT
results in the two bows canceling each other, and both tubes are counter bent to a relatively straight position). A
straighter tube package reduces the forces of extraction of the CT, which reduces damage risks to the downstream tube sheet bore.

[0054] In some embodiments, the PTST 70 can be used to rotate the severed PT
36. For example, the cutting head 74 can include one or more radially extendible grippers (e.g., shoes, expanding split rings, bungs, wedges, cams, rotating circular grippers, or other mechanisms for gripping a PT 36) that extend to engage the PT 36. Once the grippers are engaged, the cutting head 74 can be rotated (as it is rotated during the severing process or using a separate drive mechanism). In other embodiments, a separate tool can be used to rotate the PT
36. For example, in some embodiments, after the bellows 62 is cut on one end of the reactor 6 for a particular lattice site (e.g., using a cutting tool similar to the PTST 70), the bellows 62 can be rotated using the cutting tool to ensure that the bellows 62 has been properly cut and is released from the end fitting 50. Therefore, the bellows 62 cutting tool can be used in a similar fashion to rotate the PT 36.

[0055] Similarly, in some embodiments, the bellows 62 cutting tool can rotate the end fitting 50 to verify that the bellows 62 has been cut (e.g., using radially-extendible shoes and/or clamps that can be engaged and disengaged from the end-fitting 50 to prevent or to allow the end-fitting 50 to rotate as the cutting tool rotates). Rotating an end fitting 50 will also rotate the PT 36 provided that the opposite end of the PT has already been severed. Therefore, after the PT 36 has been severed at one end of the reactor but before the opposite end of the PT 36 has been severed, the bellows 62 cutting tool can be used to rotate the end fitting 50 at the opposite end of the reactor, which also rotates the PT 36.

Attorney Docket No. 027813-9038-CAOO

[0056] Furthermore, in some embodiments, the retrieval tool 100 and/or the guide tool 130 described below can be used to grip an end of a severed PT 36 and rotate the PT 36 to the removal position. For example, in some embodiments, the retrieval tool and/or the guide tool 130 described below can use their grippers to grip and rotate the PT 36. Also, in some embodiments, the tools 100 and/or 130 can include a second set of grippers that grip and rotate the severed PT 36. It should be understood that when the tools 100 and/or 130 include a second set of grippers for rotating the PT 36, the tools 100 and/or 130 can rotate the PT 36 before or after the retrieval tool and/or the guide tool 130 uses the other set of grippers to grip the CT 32.
For example, in some embodiments, the tools 100 and 130 can grip the CT 32 before or at the same time as gripping and rotating the severed PT 36 to ensure the CT 32 remains stationary.
100571 In some embodiments, while the PT 36 is rotated, the CT 32 will deflect out to the side. For example, when the PT 36 has been rotated approximately 90 degrees, the sag of the PT
36 will be sideways and the CT 32 will also deflect sideways (e.g., because the PT 36 has a slightly greater structural stiffness than that of the CT 32). The sideways sag will disappear when the PT 36 is rotated to its final 180 degrees. The momentary sideways sag of the CT 32 can be a concern depending on the nominal distance between the CT 32 and vertical reactivity mechanisms contained in the reactor. For example, in some reactors this distance is as small as approximately 5/8 of an inch. In addition, the vertical reactivity mechanisms are made from thin-walled zirconium (much like the CTs 32) and are intended to stay in position throughout a retubing process. Therefore, if the sideways sag of the CT 32 is greater than the small distance between the CT 32 and the vertical reactivity mechanisms, the sideways sag can damage the vertical reactivity mechanisms.

[00581 To overcome this concern, the direction of rotation of the PTs 36 (i.e., clockwise or counterclockwise) can be selected to avoid damage to the vertical reactivity mechanisms. In other embodiments, the CT 32 can be rotated in an opposite direction of the PT
36 rotation to counteract the sideways sag. In particular, the sag of the PT 36 can be pitted against the sag of the CT 32 during rotation of the PT 36 so that there is little or no sideways movement of the CT
32 as the PT 36 is rotated relative to the CT 32. To perform this synchronized rotation, the tool used to rotate the PT 36 can be also be configured to rotate the CT 32 in a synchronized manner.
Alternatively, a separate tool (inserted at the same end of the reactor as the tool used to rotate the Attorney Docket No. 027813-9038-CAOO

PT 36) can be used to rotate the CT 32. The tool used to rotate the CT 32 can also be configured to pull the CT 32 free from the tube sheet 18 (similar to the retrieval tool 100 described below) before rotating the CT 32.

[0059] After the severed PT 36 has been rotated (or before the rotation depending on the tool used to rotate the PT 36), the PTST 70 can be retracted from the lattice site (at 87) and the shield plug 58 can be reinstalled (at 88). The PTST 70 can then be positioned at another lattice site for PT severing (at 89) (e.g., using the HWT 72 and the RTP).

[0060] In some embodiments, the process of severing PTs 36 can be operated in parallel on opposite ends of the reactor 6. For example, one RTP and HWT can start from A-row and can be moved to sever PTs 36 down one end of the reactor 6, and a second RTP and HWT can start at Y-row and can be moved to sever PTs 36 up the opposite end of the reactor 6.

[0061] It should be understood that the PTST 70 can be remotely or locally operated and can be automated. Furthermore, the PTST 70 can be adapted to minimize any radiation emitting from the cutting head 74 and to support local control, maintenance, or troubleshooting. The PTST 70 can also be provided with one or more outboard motorized drives configured to rotate the PTST 70 and/or to actuate the cutting wheels 75 on the cutting head 74 as described above.
The drives can also include override attachments that allow the drives to be manually operated (e.g., to recover from motor failures).

[0062] In some embodiments, the cutting head 74 may require occasional maintenance or replacement (e.g., after severing approximately 40 to 60 PTs 36) to ensure cut quality consistency and to save valuable face production time. The cutting head 74 can be replaced through a semi-automated sequence to minimize radiation exposure and ensure proper installation. When PTST cutting head maintenance or replacement is needed, individuals (e.g., two tradesmen and a radiation protection qualified person) can access the PTST
70 to replace the used cutting head 74 with a new cutting head 74 containing new cutter wheels 75. A number of cutting head replacements may be performed during the processing of severing all of the PTs 36 contained in a reactor (e.g., between 8 and 12 replacements). The removed used cutting head 74 can be surveyed by qualified personnel, such as a radiation protection qualified person, and can be removed and bagged. The removed used cutting head 74 can be considered low level waste Attorney Docket No. 027813-9038-CA00 and, in some cases, does not require a shielded container for transport to the waste facility. In other embodiments, the cutting head 74 can be dismantled and the cutting wheels 75 can be replaced rather than replacing the entire cutting head 74.

[0063] A removal pallet system (also referred to as a "pallet") can be installed and implemented before or after severing the PTs 36 to remove additional components from the reactor 6. The pallet is designed to serve as a modular base for mounting and supporting various tooling systems. The pallet can be mounted on a HWT and can be controlled by one or more workstations. In some embodiment, a first workstation is used to manipulate shielding, and the another workstation is used to control a rigid chain to drive and deliver end effectors. Once installed, the pallet can remain on the HWT for the majority of the removal series.

[0064] After the pallet is installed, the end fittings 50 can be removed. With the end fittings 50 removed, the severed PTS 36 and CTs 32 can be removed. However, as described above, the CT inserts 34 (also referred to as "CTIs") attach the CTs 32 to the tube sheets 18 and hold the CTs 32 in place with a rolled joint assembly. Therefore, before the CTs 32 can be removed, the CT inserts 34 are removed. Also, in some embodiments, the CT inserts 34 are released before they are removed. Once so prepared, the CT inserts 34 can be removed from the reactor 6.

[0065] With the CT inserts 34 removed, the PTs 36 and CTs 32 can be removed from the reactor 6. In some embodiments, this process includes removing a single CT 32, PT 36, and the annulus spacers 48 placed around the PT 36 together in a single stroke from a lattice site, placing the entire package into a shielded flask, removing the flask from the vault, and installing an empty flask back onto the removal tooling. This process can be repeated as many times as necessary (e.g., approximately 380 to 480 times for some reactors) to remove all of the CTs 32, PTs 36, and annulus spacers 48 from the reactor 6. In some embodiments, a full flask can be transported in a separate stream to an on-site volume reduction system where it is emptied and returned in cue for re-installation on the removal tooling.

[0066] In some embodiments, the CTs 32, PTs 36, and annulus spacers 48 are moved through the calandria 10 from one end (hereinafter a "pushing end" ) to an opposite end (hereinafter a "receiving end") of the reactor 6. In this configuration, the receiving end comprises "receive" tooling and the pushing end comprises "guide" tooling. It should be noted, Attorney Docket No. 027813-9038-CAOO

however, that although the term "pushing" is used herein with reference to various tools and components of the reactor 6, the same tools and components need not necessarily push the CTs 32, PTs 36, and annulus spacers 48, and that the CTs 32, PTs 36, and annulus spacers 48 may only be guided through the calandria 10 in some embodiments. Accordingly, the term "push" is used for ease of description only, and is intended to encompass embodiments in which the CTs 32, PTs 36, and annulus spacers 48 are not in fact "pushed." It should also be understood that other tube and annulus spacer movement directions can be used to remove the CTs 32, PTs 36, and annulus spacers 48 from the reactor 6. Also, in some embodiments, certain packages of the CT 32, PT 36, and annulus spacers 48 ("CT-PT-AS") can be removed in one direction while other packages are removed in an opposite direction.

[0067] The CT-PT-AS removal process can be divided into automated and manual operations. Automated operations can be controlled remotely from the RCC, and can include operations that are associated with a reactor face operation with tools on a HWT. Performing these activities remotely is for "as low as reasonably achievable" ("ALARA") purposes, so that people are kept away from highly radioactive operations as much as possible.
Manual operations can include, for example, those operations associated with hoisting and transportation of flasks containing removed CT-PT-AS packages.

[0068] In some embodiments, there are no or little configuration changes of the RTPs or the HWTs before the CT-PT-AS removal process begins, and most of the tooling used in the previous series (e.g., CT insert release and removal) can be re-used in this series of steps. For example, any front extensions installed on the front of HWTs in previous series can be retained and the pallet, a lattice sleeve/shield plug insertion and removal tool ("LS-SPIRT"), a sleeve carriage, and a vision system on both reactor faces can be re-used from previous series. These common features benefit ALARA and critical path time by eliminating the need to remove, install, and commission new tools.

[0069] Transition into the CT-PT-AS removal series of steps can involve installing and commissioning one or more accessory tools onto the pallet on the RTP on both the pushing end and the receiving end of the reactor 6. These accessory tools are typically mechanical sub-assemblies that perform specialized functions in the CT-PT-AS removal series of steps. The Attorney Docket No. 027813-903 8-CAOO

accessory tools are designed to be moved on one or more floor trolleys, and hoisted by one or more vault cranes. The accessory tools required for the CT-PT-AS removal series can include a flask located at the receiving end, a retrieval tool located at the receiving end, a guide sleeve located at the receiving end, a guide tool located at the pushing end, and a guide sleeve located at the pushing end, each of which are described in more detail below. It should be understood that when the term "receiving" or "pushing" is used added to the name of particular tooling or equipment, it designates a location of the tooling or equipment. For example, the "receiving"
RTP indicates the RTP located on the receiving end of the reactor 6.
Similarly, the "pushing"
RTP indicates the RTP located on the pushing end of the reactor 6.

[0070] There are various benefits to removing the CT-PT-AS together in a single stroke from the reactor as compared with removing the PTs 36 and CTs 32 separately. First, the possibility of loose annulus spacers 48 is reduced or eliminated. This can be important when the annulus spacers 48 are made from material that attains a highly radioactive state after use in the reactor.
For example, annulus spacers 48 constructed from Inconel are many times more radioactive than annulus spacers 48 made from zirconium after use. Therefore, if Inconel annulus spacers 48 become loose, individuals could be exposed to high radiation, and there would be a loss of critical path time to recover the spacers 48. When the PT 36 is separately removed from the CT
32, loose annulus spacers 48 can be inherently generated. However, this problem is eliminated by keeping the PT 36 together with the CT 32, so that the CT 32 and the PT 36 trap the annulus spacers 48. Furthermore, as described above, by rotating the severed PT 36 from an operational position to a removal position, a load is induced on the annulus spacers due to the difference in direction of sag between the PT 36 and the CT 32 because the sag of the PT 36 has been rotated to oppose the sag of the CT 32, which provides more assurance that the spacers remain trapped.
In other embodiments, the annulus spacers 48 may be contained by inserting a ring of material that caps or fits into the annulus gap between the PT 36 and the CT 32, hence forming a vessel to trap the annulus spacers 48. As described below, rotating the PT 36 also straightens the CT-PT-AS package by counteracting the sag of both the CT 32 and the PT 36. Thus, the straighter CT-PT-AS is easier to remove from the reactor 6.

[0071] Volume reduction is also achieved by leaving the PT 36 inside the CT 32 during and after the removal process. Leaving the PT 36 inside the CT 32 decreases the traffic of flasks into Attorney Docket No. 027813-9038-CAOO

and out of the vault because fewer flasks are needed to remove the CT-PT-AS
packages than if the PTs 36 and CTs 32 were removed separately. Also, because the PTs 36 are retained in the CTs 32, which decreases the amount of removed components that have to be disposed of, less volume reduction is needed to arrive at a particular volume of radioactive material to dispose of.
Furthermore, when volume reduction is performed outside of the vault rather than in the vault, additional benefits are realized. For example, the design of tooling in the vault is simplified because in-vault volume reduction equipment does not have to be considered.
Also, by using volume reduction systems located outside of the vault, such systems can be installed, commissioned, production operated, maintained, and removed off of the critical path.
Furthermore, volume reduction systems can be set up in a dedicated Zone 3 facility, which can be used at a reactor site or between reactor units and can be maintained or refurbished without moving to another facility. The design of volume reduction systems external to vaults can also be optimized for process efficiency and reliability because the systems are not restricted in size, weight, and cycle time due to vault constraints. Fully installed and commissioned backup volume reduction systems can also be used, which help ensure little or no critical path time is wasted in troubleshooting or replacing a volume reduction system.

[0072] Removing the CTs 32 and PTs 36 together also reduces the number of removals from the calandria by half, which directly reduces critical path time. Also, the design of removal tooling in the vault is simplified because such tooling only needs to consider CT removal, and does have to consider PT removal separately.

[0073] As described in detail above, to prepare for removing a CT-PT-AS
package, the PT
36 can be severed. During this severing, the PT 36 can be severed, for example, approximately two feet inboard of the end fitting 50, and the remaining PT 36 can be rotated from an operational position to a removal position. As previously noted, by rotating the PT 36, the sag of the PT 36 (typical in existing PTs 36 used for a period of time) opposes the sag of the CT 32 (also typical in existing CTs 32 used for a period of time), which nearly straightens both out. In some embodiments, the result is a relatively small upward hump of the CT 32, because the PT 36 has a slightly greater structural stiffness than that of the CT 32.
Straightening the CT 32 makes it is easier to remove the CT-PT-AS package from the lattice site. Specifically, clearing the CT 32 from the bore of the tube sheet 18 and other horizontal components installed in the reactor is Attorney Docket No. 027813-9038-CAOO

easier and less likely to cause damages to other components when the CT 32 is as straight as possible.

[0074] After the end fittings 50 are removed (e.g., with the two-foot stub of the PT 36 attached), the ends of the remaining PT 36 sit inward (e.g., approximately two feet) from either end of the CT 32. This configuration allows grippers from removal tooling to access a diameter of the CT 32 at each end of the CT 32. Cutting the PT 36 shorter in this manner also decreases the overall influence of the sag of the PT 36 so that the residual upward hump in the resulting CT-PT-AS package is smaller.

[0075] In some embodiments, once the CT-PT-AS packages are ready to be removed, the arrangement of tools and the presence of feeder pipe cantilever supports that were not removed can dictate a flow of work across the reactor face. However, in other embodiments, for planning and monitoring purposes, the order in which the CT-PT-AS packages are removed from lattice sites is systematic (as opposed to a random order). For example, in some embodiments, there are two removal order options available that are equally efficient. The first removal order option progresses along rows to the left or to the right and then up or down as rows are completed. The second removal order option progresses along columns up or down and then to the left or to the right as each column is completed. In some embodiments, progressing along rows can be more efficient because the HWTs may be more efficient at moving to the next lattice site than the RWT platform, and the RWT platform is not moved with every flask change using the first removal order option.

[0076] FIG. 8 is a perspective view of a retrieval tool 100 according to an embodiment of the invention. The retrieval tool 100 includes an attachment 102 that attaches to the end of a rigid push pull chain (e.g., a rigid push pull chain such as that manufactured by Serapid Inc.) on the pallet. As will be described in greater detail below, the retrieval tool 100 advances through the inside of a flask, a receiving guide sleeve, a receiving CT bell, and into a CT 32 a small distance from the receiving end of the reactor 6. The retrieval tool 100 also includes one or more grippers 104 that grip a diameter of the CT with enough traction force to allow the CT
32 to be pulled one or more times to release the CT 32 from the reactor 6. The grippers 104 can include shoes, expanding split rings, bungs, wedges, cams, rotating circular grippers, or other mechanisms for Attorney Docket No. 027813-9038-CAOO

gripping a portion of the CT 32. In some embodiments, the retrieval tool 100 includes two rows of grippers, which improves traction forces by a factor of two. The additional traction force can assure that the retrieval tool 100 is able to perform a first pull on the CT
32 without slipping under nominal conditions of released joints holding the CT 32 in place. If slippage occurs, however, a guide tool (described below) can be used to provide pushing assistance to remove the CT 32. As shown in FIG. 8, the retrieval tool 100 also includes an actuator 105 for the grippers 104.

[0077] The illustrated retrieval tool 100 also incorporates a puller 106 that can generate forces sufficient for one or more pulls on the CT 32 to counteract the nominal conditions of the released joints holding the CT 32 in place. The reaction force generated by a first pull can be directed into a guide sleeve positioned at the receiving end of the reactor, which in turn can direct the reaction force onto the outboard surface of the receiving tube sheet 18. In some embodiments, the reaction force generated by subsequent pulls on the CT 32 can be directed to a brake mechanism in the flask receiving removed CT-PT-AS packages.

[0078] In some embodiments, the retrieval tool 100 can use a water-hydraulic system mounted on the pallet to perform the gripping and pulling operations. Water can be used in case there is a leak from the tooling to the reactor, in which case water will not harm the reactor other permanent reactor components (i.e., leaked water evaporates, unlike hydraulic oil which would need to be cleaned up and would tend to leave a residue). The retrieval tool 100 can maintain its grip of the CT 32 as the retrieval tool 100 is pulled out of the lattice side by the rigid push pull chain. The retrieval tool 100 can also retract clear of the flask receiving a removed CT-PT-AS
package, and can be parked inside the rigid push pull chain drive unit. In some embodiments, the retrieval tool 100 uses separate water-hydraulic lines for operating the grippers 104 and the pullers 106, which allows the grippers 104 and the pullers 106 to be controlled independently.
This independence allows the retrieval tool 100 to perform second and subsequent pulls, without requiring that the grippers 104 disengage from the CT 32 to reset the puller 106. The grippers 104 and the puller 106 can be operated by an automated control system during production. They can also be operated by manual override as needed.

Attorney Docket No. 027813-903 8-CAOO

[0079] The retrieval tool 100 can be designed to be maintenance free during a re-tube outage, but may require maintenance in between re-tube outages. It should be understood that multiple retrieval tools 100 can be used as needed, and that some retrieval tools 100 can be used as spares or for training.

[0080] FIG. 9 is a perspective view of a guide sleeve 110 positioned at the receiving end of the reactor according to an embodiment of the invention. The receiving guide sleeve 110 guides the end of the CT 32 to protect the receiving tube sheet bore from damage as a CT-PT-AS
package is removed. The receiving guide sleeve 110 also accommodates the larger diameter bell sections of the CT 32 as they pass out of the receiving tube sheet 18. In addition, the receiving guide sleeve 110 can provide a hard stop that interfaces with the retrieval tool 100 for the first pull on the CT 32 and directs the force generated by the pull through the outboard face of the receiving tube sheet 18. The receiving guide sleeve 110 can attach to a compliant mount on a sleeve carriage (see FIG. 12). In some embodiments, the receiving guide sleeve 110 is approximately 4 feet long and 6 inches in diameter, and weighs approximately 50 pounds.

[0081] With continued reference to the illustrated receiving guide sleeve embodiment of FIG. 9, a guide mechanism 112 is located at the front of the receiving guide sleeve 110, such that when the receiving guide sleeve 110 is installed into a lattice site, the guide mechanism 112 becomes located just outboard of the receiving tube sheet 18. The guide mechanism 112 can be designed with rollers that can be radially contracted onto a diameter of the CT 32 or expanded from the diameter of the CT 32. This contraction can be used to support a minor diameter of the CT 32 for protection of the receiving tube sheet 18 while the CT-PT-AS package is being removed. The reaction loads from the guide mechanism 112 can be passed onto the inboard bearing of the lattice site. The rollers can also be expanded to accommodate the larger CT bell sections when they pass through the guide mechanism 112. The rollers can also be used to promote a frictionless contact between the receiving guide sleeve 110 and the CT-PT-AS
package and to avoid wear issues.

[0082] Expansion and contraction of the guide mechanism 112 can be achieved by axially compressing or releasing the body of the receiving guide sleeve 110. This can be performed by the z-axis of the pallet, which can advance to axially compress the body of the receiving guide Attorney Docket No. 027813-9038-CAOO

sleeve 110 against the outboard face of the receiving tube sheet 18, or retract from the body of the receiving guide sleeve to release the body. This operation can be achieved by an automated system for ALARA purposes.

[0083] As also shown in the illustrated embodiment of FIG. 9, the receiving guide sleeve 110 includes an internal hardstop 114. The hardstop 114 can be integral with the guide mechanism 112 and can enable the puller 106 on the retrieval tool 100 to direct its reaction force to the outboard surface of the receiving tube sheet 18 (see FIGS. 12-13, described in greater detail below). For ALARA purposes, installation and removal of the receiving guide sleeve 110 from a lattice site can be fully automated through advance and retract operations of the pallet with a sleeve carriage, which keeps individuals away from potential open radiation beams.

[0084] The receiving guide sleeve 110 can be designed to be maintenance free during a re-tube outage, but may require maintenance between re-tube outages. In some embodiments, the above-described roller mechanism undergoes inspection with every flask change to assure proper function is maintained. The receiving guide sleeve 110 can be removed from a sleeve carriage with relative ease for maintenance purposes. Again, it should be understood that multiple receiving guide sleeves 110 can be used as needed, and that some sleeves 110 can be used as spares or for training.

[0085] FIG. 10 is a perspective view of a guide sleeve 120 positioned at the pushing end of the reactor according to an embodiment of the invention. The pushing guide sleeve 120 guides the body of a guide tool, such that its trajectory into the calandria 10 is straight. The pushing guide sleeve 120 also prevents the guide tool from making contact with the pushing end tube sheet 18. The pushing guide sleeve 120 can be attached to a complaint mount on a sleeve carriage (see FIG. 8). The compliant mount makes it easier to install or remove the pushing guide sleeve 120 from the lattice site without binding because the pushing guide sleeve 120 can be deflected slightly sideways, upward, and/or downward and is slightly angled to account for misalignments. In some embodiments, the pushing guide sleeve 120 is approximately 4 feet long and 6 inches in diameter, and weighs approximately 50 pounds.

[0086] As shown in FIG. 10, the illustrated pushing guide sleeve 120 includes guide rollers 122 to obtain nearly frictionless contact with the guide tool. The illustrated rollers 122 are Attorney Docket No. 027813-9038-CAOO

located at the front of the pushing guide sleeve 120. Therefore, when the sleeve 120 is installed into the lattice site, the rollers 122 are located just outboard of the pushing end tube sheet 18.
The rollers 122 can be configured to support the body of the guide tool so that it clears and prevents damage to the tube sheet 18. Support loads can also react against the inboard bearing of the lattice site.

[00871 For ALARA purposes, installation and removal of the pushing guide sleeve 120 from a lattice site can be fully automated through advance and retract operations of the pallet with a sleeve carriage, which keeping individuals away from potentially open radiation beams.

[00881 The pushing guide sleeve 120 can be designed to be maintenance free during a re-tube outage, but may require maintenance between re-tube outages. If maintenance is needed, the pushing guide sleeve 120 can be easily removed from the sleeve carriage.
It should be understood that multiple pushing guide sleeves 120 can be used as needed, and that some sleeves 120 can be used as spares or for training.

[00891 FIG. 11 is a perspective view of a guide tool 130 according to an embodiment of the invention. The illustrated guide tool 130 guides the trailing end of the CT 32 in the x and y directions to prevent damage to reactor components as CT-PT-AS packages are removed from the calandria 10. The guide tool 130 also provides assistance to the retrieval tool 100 during the first and any subsequent CT pulls on a contingency basis. The guide tool 130 can also include provisions to pull the CT 32 back toward the pushing tube sheet 18 on a contingency basis. The guide tool 130 can also work in cooperation with the guide sleeve 120 to prevent damage to the pushing tube sheet 18.

[00901 As shown in FIG. 11, the illustrated guide tool 130 includes a water-hydraulic pusher 132 and a brake point 133 (see FIG. 13) along a tubular body 134 that works in cooperation with a sleeve carriage (see FIG. 8). These features are designed to assist the retrieval tool 100 during the first and any subsequent pulls on the CT 32 to provide sufficient pushing force. In particular, the brake point 133 includes a positive brake device (e.g., electro-mechanical) that couples and/or locks the tubular body 134 to the sleeve carriage. The brake point 133, therefore, transfers the load generating from pushing the guide tool 130 through the sleeve carriage, the pallet system, and the HWT. In addition, the guide tool 130 can be an accessory of the pallet, Attorney Docket No. 027813-9038-CAOO

which requires less transaction time than separate tools. The guide tool 130 of the illustrated embodiment also includes rollers 136 that protect the receiving end tube sheet 18 from damage when the guide tool 130 is retracted from the lattice site. In some embodiments, the guide tool 130 is approximately 28 feet long and 4.75 inches in diameter, and weighs approximately 800 pounds.

[0091] The illustrated guide tool 130 also includes grippers 138, a flange 140, linear bearings 142, and brackets 144. The grippers 138 and rollers 136 can define a head 145 of the guide tool 130. The grippers 138 can include shoes, expanding split rings, bungs, wedges, cams, rotating circular grippers, or other mechanisms for gripping a portion of the CT 32.
The brackets 144 mount to the top surface of the pallet, and can align the tubular body 134 to the working axis of the pallet. Also, the linear bearings 142 guide the tubular body 134 in the z-direction. The flange 140 at the back of the tubular body 134 connects to the front of the rigid push pull chain of the pallet. When the rigid push pull chain is advanced, the tubular body 134 is advanced through the linear bearings 142, and when the rigid push pull chain is retracted, the tubular body 134 is retracted through the linear bearings 142. Also, the linked body of the rigid push pull chain is guided by the linear bearings 142 when in the advanced position. The guide tool 130 can be transported in the vault on floor dollies, and can be installed or removed from the pallet by hoisting.

[0092] The design of the grippers 138 and the pusher 132 on the guide tool 130 can be similar to the grippers 104 and the puller 106 on the retrieval tool 100. For example, the grippers 138 and the pusher 132 on the guide tool 130 can be operated with water-hydraulic actuators.
However, in some embodiments, because push requirements can be less than pull requirements, the guide tool 130 includes only one row of grippers. Also, the automated system for the guide tool 130 can be configured to expand the head 145 to perform a push, whereas the automated system for the retrieval tool 100 can be configured to retract the tool 100 to perform a pull. The grippers 138 of the illustrated guide tool 130 are also designed to stay engaged with the CT 32 as it moves across the calandria 10, until the pushing CT bell has been pulled through the receiving tube sheet 18 (see FIG. 20, described in greater detail below).

Attorney Docket No. 027813-9038-CAOO

[0093] The guide tool 130 can be designed to be maintenance free during a re-tube outage, but may require maintenance between re-tube outages. Also, the head 145 can be easily removed for maintenance purposes. It should be understood that multiple guide tools 130 may be used as needed, and that some guide tools 130 may be used as spares or for training.

[0094] Various contingency operations can also be performed with the removal tools. For example, tool shielding can be installed to allow individuals to troubleshoot directly on the tools when high radiation sources are present. In most cases, shielding allows tools to be fixed quickly, which allows production to be resumed. For this reason, the tooling can be designed with adequate shielding to allow individuals to perform safe troubleshooting directly on the tools.

[0095] Tooling on the receiving end of the reactor 6 can also be designed so that it can push a CT-PT-AS assembly back into the reactor 6 if needed. Likewise, tooling on the pushing end of the reactor 6 can be designed so that it can pull a CT-PT-AS assembly back into the reactor 6.
This allows a CT-PT-AS package to be cleared from the receive tooling on the receiving end of the reactor 6 so that troubleshooting and replacements and repairs can be performed to the receive tooling if necessary. Furthermore, the pallet z-drive, which advances and retracts the tooling, and the rigid push pull chain ram drive can switch to alternate servo drives if they should become inoperable. These can also be driven manually to further support recovery, if necessary.
[0096] The tooling described herein can be placed in various layouts at the reactor faces.
When CT-PT-AS packages are removed from the pushing end to the receiving end across the calandria 10, the receiving RTP can include tools considered the "receive tooling," and the pushing RTP can include tools considered the "guide tooling." For example, FIG. 12 is a perspective view of receive tooling 150 installed at a receiving end of a reactor 6 that includes the retrieval tool 100 and the receiving guide sleeve 110. As shown in FIG.
12, the receive tooling 150 also includes a HWT 152 with a front extension 154, a pallet 156, a LS-SPIRT 158, a flask 160, a sleeve carriage 162, and a vision tool 164. The vision tool 164 can be used to help align the tooling 150 with a particular lattice site 166.

[0097] Similarly, FIG. 13 is a perspective view of guide tooling 170 installed at a pushing end of the reactor 6 that includes the guide tool 130 and the pushing guide sleeve 120. As shown Attorney Docket No. 027813-903 8-CAOO

in FIG. 13, the guide tooling 170 also includes a HWT 172 with a front extension 174, a pallet 176, a LS-SPIRT 178, a sleeve carriage 180, and a vision tool 182. Again, the vision tool 182 can be used to align the guide tooling 170 with a particular lattice site 184.

[00981 FIGS. 14 and 15 are flow charts illustrating a removal process for removing a CT-PT-AS package and placing the package into a flask using the tooling described above according to some embodiments of the present invention. In some embodiments, the operations illustrated in FIGS. 14 and 15 are carried out remotely from the RCC with automated tooling.
As shown FIG.
14, to start the process, the flask 160 is mounted on the receiving pallet 156 (at 200) and the RTPs on each end of the reactor 6 are moved to the designated row (if not already located there) (at 202). In some embodiments, no workers are on the RTPs when they are moved.
The receiving and pushing HWTs 152 and 172 are also moved to the designated column (if not already located there) (at 204) and are moved sideways a predetermined amount to align the working axis of the receive tooling 150 and the guide tooling 170 respectively to the lattice site where the CT-PT-AS package will be removed (at 206). If the receive tooling 150 or the guide tooling 170 has difficulty aligning to the site, the vision systems 164 and 180 can be used to perform the alignment for troubleshooting purposes.

100991 The receive tooling 150 and the guide tooling 170 are then advanced to install the guide sleeves 110 and 120 into the lattice site (at 208). The guide tool 130 is also advanced through the pushing guide sleeve 120 and grips a diameter of the CT 32 (at 210). In some embodiments, the guide tool 130 grips a minor diameter of the CT 32 toward the pushing end of the reactor just inward of a pushing bell section 209 of the CT 32. The guide tool 130 holds the CT 32 in its current z-position, as shown in FIG. 16.

[001001 The retrieval tool 100 is then advanced through the flask 160 and the receiving guide sleeve 110 and grips a diameter of the CT 32 (at 212). In some embodiments, the retrieval tool 100 grips a minor diameter of the CT 32 toward the receiving end of the reactor just past a receiving bell section 211 of the CT 32, as shown in FIG. 17. In other embodiments, this step can be performed after, prior to, or simultaneously with the step of advancing the guide tooling 170 as described above.

Attorney Docket No. 027813-9038-CAOO

[00101] With the retrieval tool 100 gripping the CT 32 at the receiving end of the reactor, the puller 106 of the retrieval tool 100 performs a first pull of the CT 32 (at 214), which frees the CT
32 from both tube sheets 18 as shown in FIGS. 18 and 19. The reaction force generated from the pull can be directed through the outboard face of the receiving tube sheet 18 (see FIG. 18).
Should the required removal force be higher than expected, the guide tooling 170 can provide an additional push to remove the CT 32 (e.g., using the guide tool 130). The PT
36 and the annulus spacers 48 positioned inside the CT 32 are contained inside the CT 32 as the CT 32 is removed from the lattice site and are prevented from moving out of the CT 32 by the retrieval tool 100 and the guide tool 130 gripped at each end of the CT 32. Therefore, the PT 36 and annulus spacers 48 cannot fall into the calandria 10.

[00102] After the first pull, the CT 32 and its contents are moved a distance (e.g., approximately 12 inches) toward the receiving end of the reactor 6 by synchronized operation of the retrieval tool 100 and the guide tool 130 (at 216) as shown in FIGS. 20 and 21. At this point, the receiving bell section 211 of the CT 32 has cleared the expanded rollers 112 in the receiving guide sleeve 110 (see FIG. 20).

[00103] Next, the rollers of the receiving guide sleeve 110 are made to contract onto and support the receiving minor diameter of the CT 32 so it does not damage the receiving tube sheet 18 as the CT 32 is moved through the receiving tube sheet bore in the next step (at 218). Then the CT 32 and its contents are moved almost all the way across the calandria 10 by synchronized operation of the retrieval tool 100 and the guide tool 130. Throughout this operation, the trailing end of the CT 32 (i.e., the pushing end) is guided in the x and y directions by the guide tool 130 to prevent damage to other reactor components. The CT 32 is stopped when the pushing CT bell 209 is a relatively small distance (e.g., approximately 2 inches) away from fully entering the receiving tube sheet 18 (at 220) as shown in FIG. 22.

[001041 The guide rollers 112 on the receiving guide sleeve 110 are then expanded so they clear the pushing CT bell 209 (at 222), and the retrieval tool 100 performs a second pull (at 224) as shown in FIGS. 23 and 24, which moves the pushing CT bell 209 through the receiving tube sheet 18 as shown in FIG. 25. The reaction force generated by the retrieval tool 100 is directed Attorney Docket No. 027813-903 8-CA00 through a brake mechanism 225 in the flask 160 that is mounted at the receiving end of the reactor 6.

[00105] After the pushing CT bell 209 has cleared the receiving tube sheet 18, the guide tool 130 un-grips the CT 32, and the guide tool 130 is retracted back across the calandria 10 (at 226).
Small rollers 136 in the end of the guide tool 130 prevent damage to the receiving tube sheet as the guide tool 130 is retracted out of the lattice site (see FIG. 26). The guide tooling 170 (e.g., guide tool 130 and pushing guide sleeve 120) is retracted from the lattice site (at 228), the pushing HWT 172 moves sideways (at 230), and the LS-SPIRT 178 installs the shield plug back into the lattice site on the pushing end of the reactor 6 (at 232).

[00106] On the receiving end of the reactor 6, the receive tooling 150 pulls the CT-PT-AS
package into the flask 160 (at 234), and the receive tooling 150 (e.g., retrieval tool 100 and receiving guide sleeve 110) is retracted from the lattice site (at 236). The retrieval tool 100 then un-grips the CT 32 (at 238), the retrieval tool 100 is retracted from the flask 160 (at 240), the receiving end HWT 152 moves sideways (at 242), and the LS-SPIRT 158 installs the shield plug back into the lattice site (at 244).

[00107] It should be understood that in some embodiments, the guide tool 130 is advanced only partially (e.g., half way) across the calandria 10 before it is retracted. Furthermore, in some embodiments, a CT-PT-AS package can be pushed out of the reactor using the guide tool 130 without using the retrieval tool 100 to pull on the package. Similarly, in some embodiments, a CT-PT-AS package can be pulled out of the reactor using the retrieval tool 100 without using the guide tool 130 to guide and push the package.

[00108] It should also be understood that in some embodiments, the annulus spacers 48 may be removed from the lattice site before the PT 36 and the CT 32 are removed.
Also, in some embodiments, after the annulus spacers are removed, a spacer, such as a sleeve, can be inserted between the PT 36 and the CT 32 to maintain a gap between the PT 36 and the CT
32. After the spacer has been installed, the PT 36 can be rotated and the resulting CT-PT-spacer package can be removed as described above.

Attorney Docket No. 027813-9038-CAOO

[00109] As alternative embodiments, the PTs 36 and CTs 32 can be removed separately. To remove each PT 36, the PT 36 can be pulled from the fuel channel assembly 28 and into a shielded flask or a volume reduction machine that cuts the PT 36 into small pieces and places the pieces into a transfer flask. In some embodiments, PT removal begins at the bottom row of the calandria 10 and works up to the next higher row, from the lattice site near the middle of the calandria and toward the periphery sites. In some embodiments, approximately 14 to 25 PTs 36 can be removed each day in these alternate embodiments.

[00110] In some embodiments, the guide tooling 150 and/or the receive tooling 170 can be used to remove the PTs 36 and the CTs 32 separately. For example, the guide tooling 150 and/or the receive tooling 170 can be configured to remove the PT-CT-AS package and can also be configured to remove the PTs 36 and CTs 32 separately as a back-up process. In particular, to remove the PTs 36 and CTs 32 separately, the guide tool 130 on the pushing end of the reactor 6 can be used to push a severed PT 36 through the CT 32 and into a flask (while also sweeping loose annulus spacers 48 into the flask). In addition, the retrieval tool 100 can be configured to grip the PT 36 and pull the PT 36 into the flask. Also, in some embodiments, only the guide tool 130 is used to grip the PT 36 and push the PT 36 into the flask (e.g., the additional pulling force provided by the retrieval tool 100 may not be needed because the PT 36 does not need to be pulled from the tube sheet 18 as the CT). Furthermore, in some embodiments, after the guide tool 130 is used to push the PT 36 out of the CT 32 at the receiving end of the reactor, the guide tool 130 is retracted across the calandria 10 and can be configured to sweep any remaining annulus spacers 48 contained in the CT 32 to the pushing end of the reactor, where they can be deposited into a separate flask.

[00111] After the PT 36 has been removed, the flask containing the PT 36 can be removed and a new flask can be installed to receive another PT 36 at a different lattice site or to receive the CT 32 from the same lattice site. For example, in some embodiments, all of the PTs 36 are removed before the CTs 32 are removed to efficiently use removal tooling. In-other embodiments, the PT 36 and the CT 32 from the same lattice site can be removed sequentially and the same flask can be used to separately receive the PT 36 and the CT 32.
After any needed flask replacements have made performed (or after all of the PTs 36 have been removed), the CT

Attorney Docket No. 027813-9038-CAOO

32 can be removed using the guide tool 130 and the retrieval tool 100 as described above with respect to the CT-PT-AS package.

[00112] It should be understood that volume reduction can be performed at various stages of the CT and PT removal process (e.g., either as a package or separately). For example, in some embodiments, volume reduction can be performed at the face of the reactor 6 while a PT 36, a CT 32, or a CT-PT-AS package is still partially inside the reactor 6.
Furthermore, in some embodiments, after PTs 36, CTs 32, and/or CT-PT-AS packages have been placed in a flask, the full flask can be rotated (e.g., approximately 90 degrees) so it is parallel to the face of the reactor 6. The HWT and/or the RTP supporting the flask can then be moved in the y and/or the x direction to engage the front end of the flask into volume reduction tooling mounted to the vault floor or the RTP. A drive mechanism (e.g., a Serapid chain drive included in the pallet) can then push the removed reactor components from the flask into the volume reduction tooling. In yet further embodiments, the volume reduction tooling can be positioned at other locations, such as inside or outside of the reactor vault. If the volume reduction tooling is positioned outside of the reactor vault, full flasks are transported to the volume reduction tooling and empty flasks are returned to the reactor face.

[00113] Thus, embodiments of the present invention provide, among other things, methods and systems for removing CTs 32, PTs 36, and annulus spacers 48 from a nuclear reactor during a re-tubing process. It should be understood, however, that the methods and systems described herein can be performed in various orders and configurations, and some steps can be performed in parallel to other steps. Some steps can also be combined or distributed among more steps.
Also, the details of the methods and systems can be modified according to the specific configuration of the CTs, PTs, annulus spacers, and/or reactor being retubed.

[00114] Various features and advantages of the invention are set forth in the following claims.

Claims

Claims What is claimed is:

1. A method of removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor, the method comprising:

gripping, with a guide tool advanced into a lattice site from a pushing end of the reactor, at least a portion of a first diameter of the calandria tube contained in the lattice site, the calandria tube including a pressure tube rotated from an operational position to a removal position;

gripping, with a retrieval tool advanced into the lattice site from a receiving end of the reactor, at least a portion of a second diameter of the calandria tube;

pulling, with the retrieval tool, the calandria tube to remove the calandria tube from at least one tube sheet;

advancing, with the retrieval tool and the guide tool, the calandria tube and the rotated pressure tube as a package across at least a portion of the calandria toward the receiving end of the reactor;

releasing the guide tool from the first diameter of the calandria tube; and retracting the guide tool from the lattice site at the pushing end of the reactor.

2. The method of Claim 1, further comprising rotating the pressure tube from the operational position to the removal position using at least one of the guide tool and the retrieval tool.

3. The method of Claim 1, further comprising pulling, with the retrieval tool, the calandria tube and the rotated pressure tube as a package into a flask positioned at the receiving end of the reactor.

4. The method of Claim 3, further comprising releasing the retrieval tool from the second diameter of the calandria tube and retracting the retrieval tool from the flask to deposit the calandria tube and the rotated pressure tube as a package into the flask.

5. The method of Claim 4, and further comprising rotating the flask and supplying the calandria tube and the rotated pressure tube as a package to volume reduction tooling.

6. The method of Claim 1, further comprising mounting the retrieval tool on a pallet removal system configured to advance and retract the retrieval tool into and out of the lattice site from the receiving end of the reactor.

7. The method of Claim 6, further comprising mounting a flask for receiving the calandria tube and the rotated pressure tube as a package on the pallet removal system in from the lattice site at the receiving end of the reactor, wherein the retrieval tool is advanced into the lattice site through the flask.

8. The method of Claim 1, further comprising mounting the guide tool on a pallet removal system configured to advance and retract the guide tool into and out of the lattice site from the pushing end of the reactor.

9. The method of Claim 1, further comprising installing a guide sleeve into the lattice site at the receiving end of the reactor.

10. The method of Claim 9, further comprising contracting a plurality of rollers positioned on the guide sleeve onto a minor diameter of the calandria tube as the calandria tube and the rotated pressure tube are moved as a package out of the lattice site at the receiving end of the reactor.

11. The method of Claim 10, further comprising expanding the plurality of rollers to accommodate a first bell and a second bell of the calandria tube as the calandria tube and the rotated pressure tube are moved as a package out of the lattice site at the receiving end of the reactor.

12. The method of Claim 1, further comprising installing a guide sleeve into the lattice site at the pushing end of the reactor, the guide sleeve including a plurality of rollers for supporting the guide tool as the guide tool is advanced into the lattice site.

13. The method of Claim 1, further comprising pushing, with the guide tool, the calandria tube to remove the calandria tube from the at least one tube sheet.

14. The method of Claim 1, further comprising contracting a plurality of rollers positioned in a guide sleeve installed into the lattice site at the receiving end of the reactor to support a minor diameter of the calandria tube.

15. The method of Claim 14, further comprising expanding the plurality of rollers to clear a bell in the calandria tube.

16. A tool for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor, the tool comprising:

a retrieval tool configured to be positioned within a diameter of a calandria tube contained in a lattice site, the calandria tube including a pressure tube rotated from an operational position to a removal position;

at least one gripper positioned on the retrieval tool, the at least one gripper configured to grip at least a portion of the diameter of the calandria tube; and a puller positioned on the retrieval tool, the puller configured to pull the calandria tube free from at least one tube sheet, the retrieval tool configured to move the calandria tube and the rotated pressure tube as a package across the calandria

17. The tool of Claim 16, wherein the at least one gripper is further configured to release the diameter of the calandria tube after the calandria tube and the rotated pressure tube are removed from the lattice site as a package.

18. The tool of Claim 16, wherein the at least one gripper includes a plurality of grippers arranged in two rows.

19. The tool of Claim 16, further comprising a water-hydraulic system configured to actuate the at least one grip and release the at least one grip.

20. The tool of Claim 19, wherein the water-hydraulic system is further configured to actuate the puller.

21. The tool of Claim 19, wherein the water-hydraulic system is further configured to actuate and release the at least one grip independently of actuating the puller.

22. A tool for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor, the tool comprising:

a guide tool configured to be positioned within a diameter of a calandria tube contained in a lattice site, the calandria tube including a pressure tube rotated from an operational position to a removal position;

at least one gripper positioned on the guide tool, the at least one gripper configured to grip at least a portion of the diameter of the calandria tube; and a pusher positioned on the guide tool configured to push the calandria tube and the rotated pressure tube as a package across at least a portion of the calandria.

23. The tool of Claim 22, wherein the at least one gripper is further configured to release the diameter of the calandria tube after the calandria tube and the rotated pressure tube are removed from the lattice site as a package.

24. The tool of Claim 22, wherein the at least one gripper and the pusher are actuated by a water-hydraulic system.

25. The tool of Claim 22, further comprising a tubular body including the at least one gripper and the pusher.

26. The tool of Claim 25, further comprising a sleeve carriage for advancing and retracting the tubular body into and out of the lattice site at the pushing end of the reactor.

27. The tool of Claim 25, further comprising linear bearings for guiding the tubular body into and out of the lattice site at the pushing end of the reactor.

28. A system for removing a calandria tube and a pressure tube from a calandria of a nuclear reactor as a package during retubing of the reactor, the system comprising:

a retrieval tool configured to be advanced into a lattice site including a calandria tube and a pressure tube rotated from an operational position to a removal position from a receiving end of the reactor until the retrieval tool is positioned within a first diameter of the calandria tube, to grip at least a portion of the first diameter of the calandria tube, to pull the calandria tube to release the calandria tube from at least one tube sheet, and to move the calandria tube and the rotated pressure tube as a package across a calandria and out of the lattice site at the receiving end of the reactor; and a guide tool configured to be advanced into the lattice site from a pushing end of the reactor until the guide tool is positioned within a second diameter of the calandria tube, to grip at least a portion of the second diameter of the calandria tube, and to guide the calandria tube and the rotated pressure tube as a package across at least a portion of the calandria toward the receiving end of the reactor.

29. The system of Claim 28, wherein the first diameter includes a minor diameter of the calandria tube located toward the receiving end of the reactor and the second diameter includes a minor diameter of the calandria tube located toward the pushing end of the reactor.

30. The system of Claim 28, further comprising:

a first pallet removal system positioned at the receiving end of the reactor and configured to advance the retrieval tool into the lattice site and retract the removal tool from the lattice site, and a second pallet removal system positioned on the pushing end of the reactor and configured to advance the guide tool into the lattice site and retract the guide tool from the lattice site.

31. The system of Claim 28, further comprising a flask configured to receive the calandria tube and the rotated pressure tube as a package at the receiving end of the reactor.

32. The system of Claim 28, further comprising a guide sleeve installed in the lattice site at the receiving end of the reactor, the guide sleeve including a plurality of rollers configured to onto a minor diameter of the calandria tube and configured to expand for a first bell and a second bell of the calandria tube as the calandria tube and the rotated pressure tube are moved as a package out of the lattice site at the receiving end of the reactor.

33. The system of Claim 28, further comprising a guide sleeve installed in the lattice site at the pushing end of the reactor, the guide sleeve including a plurality of rollers configured to support the guide tool as the guide tool is advanced into and retracted from the lattice site at the pushing end of the reactor.

34. A method of removing a calandria tube, a pressure tube, and a plurality of annulus spacers from a calandria of a nuclear reactor during retubing of the reactor, the method comprising:

gripping at least a portion of a first diameter of the pressure tube from a pushing end of the reactor;

advancing the pressure tube across the calandria to a receiving end of the reactor and into a flask;

sweeping the plurality of annulus spacers from within the calandria tube;

gripping at least a portion of a first diameter of the calandria tube from a pushing end of the reactor;

gripping at least a portion of a second diameter of the calandria tube from a receiving end of the reactor; and advancing the calandria tube across the calandria to the receiving end of the reactor.

35. The method of Claim 34, further comprising depositing the calandria tube into a second flask at the receiving end of the reactor.

36. The method of Claim 34, wherein sweeping the plurality of annulus spacers from within the calandria tube includes sweeping the plurality of annulus spacers toward the pushing end of the reactor and into a second flask.

37. The method of Claim 34, further comprising gripping at least a portion of a second diameter of the pressure tube from a receiving end of the reactor.

38. The method of Claim 34, further comprising supplying at least one of the pressure tube and the calandria tube to a volume reduction system.