WO2018232508A1

WO2018232508A1 - Inspection tool and method for nuclear reactor fuel channel assembly

Info

Publication number: WO2018232508A1
Application number: PCT/CA2018/050751
Authority: WO
Inventors: John DROSSIS; Kevin DI CARLO; Robert William JAMIESON; Ron ROWE; Jason DEADMAN
Original assignee: Candu Energy Inc.
Priority date: 2017-06-23
Filing date: 2018-06-20
Publication date: 2018-12-27
Also published as: KR102656972B1; CN111194469A; CA3066101A1; KR20200019893A; RO134272A2; CN111194469B

Abstract

Systems and methods for inspecting an interior surface of an element within a nuclear reactor. One system includes an inspection tool including a camera, a tool control system communicating with the inspection tool to control a rotational position of the inspection, and a workstation. The workstation is configured to receive image data captured with the camera at each of a plurality of rotational positions of the inspection tool and generate a panoramic image based on the image data. The workstation is also configured to automatically detect at least one defect within the panoramic image, and generate and output an inspection report, the inspection report including the panoramic image and data regarding the at least one defect.

Description

INSPECTION TOOL AND METHOD FOR NUCLEAR REACTOR FUEL CHANNEL ASSEMBLY

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims all benefit including priority to U.S. Provisional Patent Application 62/524,113, filed June 23, 2017, and entitled "INSPECTION TOOL AND

METHOD FOR NUCLEAR REACTOR FUEL CHANNEL ASSEMBLY", the entirety of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] Embodiments described herein relate to methods and systems for inspecting an annular component, such as a calandria tube sheet bore or a bellows portion of a nuclear reactor fuel channel assembly.

BACKGROUND

[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 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, and severing and removing pressure tubes and 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 may include a plurality of bores, each of which 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 installation of a new fuel channel assembly.

SUMMARY

[0005] A tube sheet bore may be manually inspected (visually), but this process is time- consuming, subjective, and may result in under-inspection or over-inspection of a particular bore. For example, as a nuclear reactor may generate approximately $1 million to $2 million dollars per day when operational, any delays during the retubing process can translate to millions of dollars in lost revenue. Thus, for many reactors (including CA DU™-type reactors described above), advanced inspection tooling capable of efficiently performing inspection of the tube sheet bore associated with each fuel channel assembly would be a welcome improvement.

[0006] Accordingly, embodiments described herein provide tools and methods for inspecting tube sheet bores to streamline and at least partially automate much of the process of performing visual inspection of tube sheet bores in situ in a nuclear reactor. For example, one embodiment provides a system for inspecting an interior surface of an element within a nuclear reactor. The system includes an inspection tool including a camera, a tool control system communicating with the inspection tool to control a rotational positon of the inspection tool, and a workstation. The workstation can be configured to receive image data captured with the camera at each of a plurality of rotational positions of the inspection tool, generate a panoramic image based on the image data, automatically detect at least one defect within the panoramic image, and generate and output an inspection report, the inspection report including the panoramic image and data regarding the at least one defect.

[0007] In accordance with one aspect, there is provided a system for inspecting an interior surface of an element within a nuclear reactor. The system includes: an inspection tool including a camera for capturing image data of the interior surface of the element; a tool control system communicating with the inspection tool and for positioning the camera; and a workstation. The workstation is configured to: receive image data captured with the camera, detect at least one defect within the image data, and generate and output an inspection report, the inspection report including the received image data and data regarding the at least one defect. [0008] In accordance with another aspect, there is provided a method of inspecting an interior surface of an element within a nuclear reactor. The method includes: capturing image data of the interior surface of the element using a camera of an inspection tool inserted within the element; detecting at least one defect within the captured image data; marking the at least one defect within the captured image data; and outputting the captured image data with the marked at least one defect.

[0009] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] FIG. 1 is a perspective view of a CANDU™-type reactor.

[0011] FIG. 2 is a cutaway view of a CANDU™-type nuclear reactor fuel channel assembly.

[0012] FIG. 3 is a perspective view of an inspection tool according to one embodiment.

[0013] FIG. 4 is a perspective view of a mirror housing included in the inspection tool of FIG. 3.

[0014] FIG. 5 schematically illustrates an inspection system including the inspection tool of FIG. 3 according to one embodiment.

[0015] FIG. 6 is a flow chart illustrating a method of inspecting a bore of a tube sheet performed by the system of FIG. 5 according to one embodiment.

[0016] FIG. 7 illustrates example image data collected by a camera included in the inspection tool of FIG. 3.

[0017] FIG. 8 illustrates an example panoramic view generated by the system of FIG. 5 based on image data collected by the camera included in the inspection tool of FIG. 3.

[0018] FIG. 9 illustrates example image data collected by a camera included in an inspection tool used to inspection bellows of a nuclear reactor. [0019] FIG. 10 illustrates an example region of interest identified in the image of FIG. 9, and a flat rectangular strip representing an annular region of interest identified in the image of FIG. 10.

[0020] FIG. 11 illustrates an example panoramic image generated for a region of interest of a bellows.

[0021] FIG. 12 illustrates a gradient filter applied to the panoramic image of FIG. 11.

[0022] FIG. 13 illustrates example bellows measurements calculated from image data.

[0023] FIG. 14 illustrates an example panoramic image overlaid with a coordinate system for reporting purposes.

DETAILED DESCRIPTION

[0024] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the

accompanying drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.

[0025] 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. Although aspects of the invention are described with particular reference to the CANDU™-type reactor 6 for convenience, the invention is not limited to CANDU™-type reactors, and may be useful outside this particular field as well. Returning to FIG. 1, a generally cylindrical vessel, known as the calandria 10 of the CANDU™-type reactor 6, 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 apertures (referred to herein as "bores") that each accept a fuel channel assembly 28. As shown in FIG. 1, a number of fuel channel assemblies 28 pass through the tube sheets 18 of calandria 10 from the first end 22 to the second end 24. [0026] As in the illustrated embodiment, in some embodiments the reactor core is provided with two walls at each end 22, 24 of the reactor core: an inner wall defined by the tube sheet 18 at each end 22, 24 of the reactor core, and an outer wall 64 (often referred to as a "end shield") located a distance outboard from the tube sheet 18 at each end 22, 24 of the reactor core. A lattice tube 65 spans the distance between the tube sheet 18 and the end shield 64 at each pair of bores (i.e., in the tube sheet 18 and the end shield 64, respectively).

[0027] FIG. 2 is a cutaway view of one fuel channel assembly 28 of the reactor core illustrated in FIG. 1. As illustrated in FIG. 2, each fuel channel assembly 28 includes a calandria tube ("CT") 32 surrounding other components of the fuel channel assembly 28. The CTs 32 each span the distance between the tube sheets 18. Also, the opposite ends of each CT 32 are received within and sealed to respective bores in the tube sheets 18. In some embodiments, a CT rolled joint insert 34 is used to secure the CT 32 to the tube sheet 18 within the bores. 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.

[0028] As also shown in FIG. 2, each end of each fuel channel assembly 28 is provided with an end fitting 50 located outside of the corresponding tube sheet 18. At the terminal end of each end fitting 50 is a closure plug 52. Each end fitting 50 also includes a feeder assembly 54. The feeder assemblies 54 feed reactor coolant into or remove reactor coolant from the PTs 36 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, and the feeder assembly 54 on the opposite end of the fuel channel assembly 28 acts as an outlet feeder. As shown in FIG. 2, the feeder assemblies 54 can be attached to the end fittings 50 using a coupling assembly 56 including a number of screws, washers, seals, and/or other types of connectors. The lattice tube 65 (described above) encases the connection between the end fitting 50 and the PT 36 containing the fuel assemblies 40. Shielding ball bearings 66 and cooling water surround the exterior of the lattice tubes 65, which provides additional radiation shielding.

[0029] 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 - 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 CA DU™-type reactor is illustrated in FIGS. 1-2, the invention may also apply to other types of reactors, including reactors having components that are similar to those illustrated in FIGS. 1-2.

[0030] FIGS. 3 and 4 illustrate an inspection tool 100 according to one embodiment. The inspection tool 100 includes a support 102 and an end cap 103. The support 102 (or other components of the tool 100) may include a support clamp or other interface for installing the inspection tool 100 adjacent the calandria 10 of the nuclear reactor, such as on a mobile work table. The work table or other support surface supporting the inspection tool 100 carries and supports the inspection tool 100 from lattice site to lattice site (positions on each side of the reactor 6 defined by the locations of the fuel channel assemblies 28 described above) across the face of the calandria 10. In some embodiments, the work table is laterally movable in an x direction (for example, upon rails, on a cart, and the like), axially movable toward and away from the reactor face in a y direction, vertically movable in a z direction, or a combination thereof. The x, y, and z directions are labeled in FIG. 1. In some embodiments, the support 102 (or other components of the tool 100) also interfaces with a tool control system that includes motors or other actuators for controlling a position of the inspection tool 100, such as the rotation of the tool 100 (radial movement), axial movement of the tool 100, or a combination thereof. In some embodiments, the tool control system may comprise motors or other actuators for controlling a position of a camera 112 of the tool 100, such as the rotation or rotational position of the camera 112 (radial movement), axial position or axial movement of the camera 112, or a combination thereof. The tool control system may control the radial position of the camera 112 or the tool 100 relative to an axis of an element (e.g. rotating the camera 112 or the tool 100 relative to a longitudinal axis of an element to a desired rotational position) of the nuclear reactor 6 that may be inspected. The tool control system may control the axial position of the camera 112 or the tool 100 relative to an element (e.g. moving the camera 112 or the tool 100 along a longitudinal axis of an element to a desired axial position) of the nuclear reactor 6 that may be inspected.

[0031] The tool 100 and the associated methods described herein may be used as part of a nuclear reactor retubing procedure. Depending on the results of the inspection and the component inspected, the inspected component may be removed and replaced as part of retubing procedure, or one or more operations can be performed on the component in situ as part of the retubing process. The inspection tool 100 and the associated methods may also be used during other processes, including during manufacturing, installation, or maintenance of the reactor 6 regardless of whether retubing is being performed. For the sake of discussion, the remaining discussion refers to inspection of a bore of a tube sheet 18, but aspects of the tool 100 and the associated inspection methods are not limited to the tube sheet 18. For example, the tool 100 may similarly be used to inspect another element of the nuclear reactor 6, such as an interior surface of a lattice tube 65, a bellows 62, an end shield bore 64, and other interior surfaces of the nuclear reactor 6 that may be otherwise difficult to inspect.

[0032] As illustrated in FIGS. 3 and 4, the support 102 and the end cap 103 may be cylindrically shaped to be positioned within a cylindrically-shaped tube sheet bore. However, in other embodiments, the support 102, the end cap 103, or both may have other shapes or configurations. The illustrated end cap 103 includes a recess 104. A mirror housing 105 is mounted within the recess 104, and includes a mirror 106. The mirror 106 may have a skewed orientation with respect to a longitudinal axis A extending along the length of the support 102 and end cap 103, such as approximately a 45 degrees angle with respect to the axis A. The mirror 106 may be held in position by a bracket 108. In some embodiments, the mirror housing 105 also includes a mechanism powered by a motor (not shown) to adjust the position (tilt or pivot) of the mirror 106 with respect to the axis A. In this embodiment, the mirror housing 105 and/or the bracket 108 may include a locking mechanism, such as a mechanical lock, to prevent movement of the mirror 106. Alternatively, in some embodiments, the mirror 106 is secured within the housing 105 at a fixed angle.

[0033] As illustrated in FIGS. 3 and 4, the mirror housing 105 includes an opening to allow light entering the recess 104 to reach the mirror 106. Although not illustrated in FIGS. 3 or 4, in some embodiments, a transparent window (formed from glass, acrylic, plastic, or another transparent material) is positioned on the end cap 103 to at least partially enclose the recess 104. The window may protect the mirror housing 105 from debris and damage during use of the tool 100 while still allowing light to reach the mirror 106. The recess 104 may also include other components, such as a vacuum tube 110, which may be used to remove dust or other debris during the inspection process. The vacuum tube 110 may extend through or around any enclosure or window on the recess 104 to establish fluid communication between an interior of the vacuum tube 110 and the exterior environment around the tool 100. The recess 104 may also include at least one light source (not shown; for example, a collimated light source, bulb(s), light emitting diodes, and the like) configured to emit visible light. In some embodiments, the light source is positioned to direct light out of the recess 104. Light emitted by the light source may be reflected by the mirror 106 to direct the light out of the recess 104.

[0034] The tool 100 comprises a camera 112 that is positioned within or adjacent the mirror housing 105, such as within the end cap 103 or the support 102 (see, for example, FIG. 4). The camera 112 may capture image data of the interior surface of the bore. The camera 112 is positioned inward with respect to the mirror 106 along the axis A. The camera 112 is oriented to capture images along the axis A toward an axial end of the end cap 103, which during use is inserted into a bore of a tube sheet 18 or other nuclear reactor component being inspected. The camera 112 may be a digital camera operable to collect still images, continuous video images, or a combination thereof through an optical sensor. The camera 112 may be a color camera, a black and white camera, an infrared camera, or other suitable type of camera. The camera 112 stores collected images to an electronic data storage device, such as a removable memory card or an internal memory of the camera 112. The collected images may also be transmitted via a network to an external storage device. One or more lenses may be positioned in in front of the camera exposure, such as via an automatic or manually controlled iris or aperture. This aperture can also be controlled by the machine vision software (described below). In some embodiments, the camera 112 also includes at least one light source configured to emit light out of the recess 104. This light source may be used in place of or in addition to a separate light source positioned within the recess 104 as described above. Furthermore, in some embodiments, the inspection tool 100 includes one or more other lights at other positions, such as on an exterior surface of the end cap 103, the support 102, or a combination thereof.

[0035] In some embodiments, the camera 112 is oriented to capture images along an axis that is not parallel to the axis A. For example, the camera 112 is oriented to capture images along an axis that is generally perpendicular with respect to the axis A. In such an example, the camera 112 may be oriented to capture images through an opening defined by the inspection tool 100, such as an opening defined in the end cap 103. The tool control system may comprise motors or other actuators for controlling a position of the camera 112, such as the rotation or rotational position of the camera 112 (radial movement), axial position or axial movement of the camera 112, or a combination thereof. The tool control system may control the radial position of the camera 112 relative to an axis of an element (e.g. rotating the camera 112 relative to a longitudinal axis of an element to a desired rotational position) of the nuclear reactor 6 that may be inspected. The tool control system may control the axial position of the camera 112 relative to an element (e.g. moving the camera 112 along a longitudinal axis of an element to a desired axial position) of the nuclear reactor 6 that may be inspected. The camera 112 may capture image data at a first position, the position of the camera 112 may be changed axially or rotationally from the first position to a second position, and the camera 112 may capture image data at the second position.

[0036] The mirror 106 of the illustrated embodiment is positioned to reflect light toward the camera 112. For example, with the camera 112 oriented to capture images along axis A as described above, the mirror 106 may be positioned at 45 degrees with respect to axis A to provide the camera 112 with an approximately right-angle view of a tube sheet bore when the end cap 103 is positioned within the bore. In some embodiments, the tool 100 may not comprise a mirror 106 when the camera 112 may be oriented to capture images through an opening defined by the inspection tool 100.

[0037] As noted above, the inspection tool 100 may interface with a tool control system, which may control movement and positioning of the camera 112 or inspection tool 100. For example, FIG. 5 schematically illustrates an inspection system 200 according to one

embodiment. The illustrated system 200 includes the inspection tool 100, a tool control system 202, and a workstation 203. The inspection tool 100 and the tool control system 202 may communicate wirelessly or over a wired connection. For example, in some embodiments, the inspection tool 100 communicates with the tool control system 202 over a Supervisory Control and Data Acquisition (SCAD A) network 204 associated with the nuclear reactor 6. As illustrated in FIG. 5, the tool control system 202 may include an electronic processor, such as a programmable logic controller (PLC), a microprocessor, an application-specific integrated circuit (ASIC), a programmable logic device (for example, a field-programmable gate array), or other suitable electronic device configured to receive input, process data (including received input), and output data. The tool control system 202 may include other components, such as non- transitory computer readable medium storing executable instructions or other data or one or more communication interfaces for communicating with one or more networks or data or control lines or buses. For example, in some embodiments, the tool control system 202 includes a network interface card (NIC) for communicating with the SCADA network 204. In some embodiments, the tool control system 202 may also include one or more human machine interfaces (UMIs) for receiving input from or providing output to a user, such as a keyboard, keypad, a button, lever, touchscreen, speaker, display, and the like.

[0038] As illustrated in FIG. 5, the tool control system 202 communicates with a local tool controller 206 included in the inspection tool 100. The local tool controller 206 acts as an interface between the tool control system 202 and one or more motors, actuators, or other components configured to change the position of the camera 112 or the inspection tool 100. For example, as illustrated in FIG. 5, the inspection tool 100 may include a radial motor 208. The radial motor 208 controls a radial (rotational) position of the camera 112 or the inspection tool 100 (for example, in 1 degree increments). Although the radial motor 208 is illustrated in FIG. 5 as being included in the inspection tool 100, in some embodiments, the radial motor 208 is external to the inspection tool 100. In some embodiments, the inspection tool 100 includes or uses other motors, including for example an axial motor. The local tool controller 206 may also provide feedback to the tool control system 202, such as the current axial position or rotational position of the camera 112 or the inspection tool 100. For example, the radial motor 208 may be associated with an encoder (axial or rotary) that senses a position of the axial motor or the radial motor 208 and converts the sensed position into an electronic signal. The local tool controller 206 may receive this signal from the encoder and forward this signal to the tool control system 202. As described in more detail below, the tool control system 202 may forward the encoder signal to the workstation 203. Although not illustrated in FIG. 5, the local tool controller 206 may include an electronic processor, non-transitory computer-readable medium, a

communication interface, or a combination thereof similar to the tool control system 202.

[0039] The workstation 203 may include a computing device, such as personal computer, laptop computer, tablet computer, computer terminal, or other electronic device. For example, as illustrated in FIG. 5, the workstation 203 includes an electronic processor 210 (for example, a PLC, a microprocessor, an ASIC, programmable logic device, or other suitable electronic device configured to process data), a storage device 212, and a communication interface 214. In some embodiments, the workstation 203 also includes a UMI 216. The electronic processor 210, the storage device 212, the communication interface 214, and the UMI 216 are communicatively coupled over one or more communication lines or buses, wirelessly, or combinations thereof. It should be understood that in other constructions, the workstation 203 includes additional, fewer, or different components than those illustrated in FIG. 5, such as multiple storage devices 212 or multiple HMIs 216.

[0040] The storage device 212 can include a non-transitory, computer-readable storage medium storing program instructions and data. The electronic processor 210 is configured to retrieve instructions from the storage device 212 and execute the instructions to perform a set of functions, including the methods described herein. The UMI 216 receives input from and provides output to users, such as operators or other personnel managing the retubing process for the reactor 6. The UMI 216 may include a keyboard, a keypad, a microphone, a camera, a cursor-control device (for example, a mouse, a joystick, a trackball, a touch pad, and the like), a display (for example, a liquid crystal display (LCD), a light emitting diode (LED) display, a touchscreen), a speaker, and the like.

[0041] The workstation 203 communicates with the tool control system 202 (e.g., over the SCADA network 204) via the communication interface 214. In some embodiments, the communication interface 214 includes a wireless transceiver for wirelessly communicating with the tool control system 202, such as radio frequency (RF) transceiver for communicating over a communications network (for example, the Internet, a local area network, Wi-Fi, Bluetooth, or a combination thereof). Alternatively or in addition, the communication interface 214 may include a port for receiving a cable, such as an Ethernet cable, for communicating with the tool control system 202 (over a dedicated wired connection or over a communications network). As described in more detail below, the workstation 203 may communicate with the tool control system 202 (e.g., over the SCADA network 204) to issue instructions (signals) for changing the position of the camera 112 or the inspection tool 100. The tool control system 202 relays these instructions to the local tool controller 206 as described above. The workstation 203 may also communicate with the tool control system 202 over the SCADA network 204 to receive the axial position or the rotational position of the camera 112 or the inspection tool 100, which may include a signal from an encoder as described above. In some embodiments, the workstation 203 authenticates itself with the tool control system 202 through a handshake algorithm for security and control purposes.

[0042] As illustrated in FIG. 5, the illustrated workstation 203 also communicates with the inspection tool 100. In some embodiments, the workstation 203 communicates with the inspection tool 100 via the same communication interface 214 used to communicate with the tool control system 202. In other embodiments, the workstation 203 includes a separate

communication interface for communicating with the inspection tool 100. For example, the workstation 203 may communicate with the inspection tool 100 over a video observation system (VOS) network 220 and, therefore, can include a dedicated NIC for communicating over this type of network.

[0043] In the illustrated embodiment, the workstation 203 communicates with the inspection tool 100 over the VOS network 220 to obtain image data collected by the camera 112 included in the tool 100. For example, as illustrated in FIG. 5, the inspection tool 100 may include a local camera controller 222 that acts as an interface between the camera 112 and the VOS network 220. Although not illustrated in FIG. 5, the local camera controller 222 may include an electronic processor, non-transitory computer-readable medium, a communication interface, or a combination thereof similar to the tool control system 202. As described in more detail below, in some embodiments the workstation 203 also communicates with the local camera controller 222 to issue instructions (signals) for controlling the camera 112, such as changing the axial position or rotational position of the camera 112, turning the camera 112 on or off, or changing settings of the camera 112, such as exposure.

[0044] FIG. 6 illustrates a method 300 of inspecting a tube sheet bore using the system 200. The method 300 includes inserting the inspection tool 100 into a tube sheet bore (at block 302). This process may be performed using one or more automated platforms, work tables, or a combination thereof that position the inspection tool 100 in front of a tube sheet 18 and axially extend the inspection tool 100 such that the end cap 103 (the recess 104) is positioned within the tube sheet bore.

[0045] After the inspection tool 100 is properly positioned within the bore, the camera 112 is positioned and collects image data of the interior surface of the bore at a current position (e.g. current axial position and rotational position) of the inspection tool 100 (at block 304). In some embodiments, the starting position of the tool 100 may be the position of the tool 100 when the tool 100 is initially inserted into the bore (which may be set prior to insertion). In other embodiments, the workstation 203 may position the inspection tool 100 (through the tool control system 202) to a predetermined starting position (e.g. predetermined starting axial position and rotational position) before or after the tool 100 is inserted into the bore. In some embodiments, the camera 112 may be positioned at an axial or rotational position to capture image data of the interior surface of the bore.

[0046] The workstation 203 receives the image data collected by the camera 112 (for example, over the VOS network 220) (at block 306). FIG. 7 illustrates one example of image data 307 collected by the camera 112. The workstation 203 associates the received image data with a position of the camera 112 or the inspection tool 100, such as the axial position or rotational position of the camera 112 or the inspection tool 100 (at block 308). For example, as described above, the workstation 203 may receive a rotational position of the camera 112 or the inspection tool 100 from the tool control system 202, which the workstation 203 associates with image data collected by camera 112 while the camera 112 or the inspection tool 100 remains in this position. In particular, the workstation 203 may store the image data in a mapping or data table along with the axial position or the rotational position, or may add the axial position or the rotational position to metadata of the image data. The workstation 203 may be configured to associate image data with received encoder data or an axial rotation or rotational position represented by the encoder data. For example, the workstation 203 may be configured to translate received encoder data into an axial position or rotational position of the camera 112 or the inspection tool 100 from a predetermined starting position. In other embodiments, alternatively or in addition to associating an actual axial or rotational position (as defined by encoder data) with received image data, the workstation 203 may associate an expected axial or rotational position with received image data. For example, by tracking issued movement instructions (e.g. axial movement instructions or rotation instructions) transmitted to the tool control system 202, the workstation 203 may determine a current expected axial or rotational position of the inspection tool 100 from a known starting position. In these cases, the workstation 203, however, may still receive the encoder data to verify axial movement or rotational movement of the tool 100.

[0047] Before or after associating received image data with an axial position or rotational position of the tool 100, the workstation 203 processes the received image data (at block 310). In some embodiments, the workstation 203 (the electronic processor 210) executes machine vision software (stored in the storage device 212) to process the image data as the tool 100 is being moved (e.g. moved axially or rotated) to track the movement of the tool 100 and verify the distance travelled (axial distance or circumferential distance travelled). This information may be used to adjust the movement instruction (e.g. axial movement instruction or rotation instruction) transmitted to the tool control system 202 for a subsequent movement. For example, the workstation 203 may compare movement of features included in the image across the camera view as the camera 112 or the inspection tool 100 rotates with the angle moved as indicated by an encoder. Depending on this comparison, the workstation 203 may control the camera 112 or the inspection tool 100 to rotate a greater of lesser number of degrees in a subsequent movement to maintain the image scan width and to aid the joining or stitching of images as described below.

[0048] In some embodiments, the camera 112 transmits a single image to the workstation 203 for a current position (e.g. current rotational position) of the camera 112 or the tool 100. In other embodiments, the camera 112 transmits a plurality of images to the workstation 203 for the current position (e.g. current rotational position) of the camera 112 or the tool 100. When the camera 112 transmits multiple images, the workstation 203 may average the image data to generate a single, average image. Averaging the images may include finding the mean pixel value over the number of images (captured in a series). Averaging may help reduce noise in the images. Alternatively or in addition, the workstation 203 may select one of the plurality of images as the representative image based on the quality of each image (for example, the brightness, contrast, noise, artifacts, distortion, glare, and the like).

[0049] Regardless of whether the camera 112 transmits one or a plurality of images, the workstation 203 may also process the received image data to detect and reject images that suffer from one or more quality issues (at block 314). For example, the workstation 203 may determine whether the received image data has an expected format or pattern to ensure that the camera 112 is collecting images of the interior surface of the bore rather than other components of the tube sheet or other portions of the reactor 6. The workstation 203 may reject an image when an image has failed to capture data regarding the specific component under consideration. The

workstation 203 may also evaluate whether an image has proper exposure and may reject images not properly exposed. Similarly, the workstation 203 may process received images to detect and reject blank images, corrupt images, images with missing pixel values, or images with other artifacts or noise. When the workstation 203 rejects a received image, the workstation 203 may instruct the camera 112 to collect additional image data for the current position (e.g. rotational position) of the camera 112 or the tool 100. In some embodiments, the workstation 203 also takes one or more actions to improve the quality of subsequent images collected by the camera 112. For example, the workstation 203 may send instructions (signals) to the local camera controller 222 to change a setting of the camera 112 (position, exposure, focus, and the like), a light source included in the inspection tool 100, or a combination thereof. In other embodiments, however, camera settings may be locked when the inspection method 300 is started to prevent variances between image data that could be falsely identified as defects in the bore.

[0050] In some embodiments, after processing received image data to detect defects and while the camera 112 or the inspection tool 100 has not been positioned to capture additional image data, for example, while the camera 112 or the inspection tool 100 has not rotated a predetermined number of degrees (for example, 360 degrees) (at block 318), the workstation 203 sends instructions (signals) to the tool control system 202 to position the camera 1 12 or the tool 100 to another position, such as to rotate the camera 112 or the inspection tool 100 from a first rotational position to a second rotational position (at block 316). Image data of the interior surface of the bore may be captured with the camera 112 at a first position, the camera 112 may be rotated to a second position, and image data of the interior surface of the bore may be captured with the camera 112 at the second position. For example, the workstation 203 may rotate the inspection tool 100 in predetermined increments (e.g., 1 degree to 10 degrees) until image data is collected for 360 degrees of the interior surface of a bore, or in other embodiments for some desired subset of 360 degrees of the interior surface of the bore. In other embodiments, the workstation 203 may rotate the inspection tool 100 through constant movement. As illustrated in FIG. 6, at each rotational position, the workstation 203 processes received image data as described above. The camera 112 may capture image data at a plurality of positions (e.g. a plurality of rotational positions), and the workstation 203 may be configured to receive image data captured with the camera 112 at a plurality of positions (e.g. a plurality of rotational positions).

[0051] After the camera 1 12 or the inspection tool 100 has been moved to a plurality of positions (e.g. rotates a predetermined number of degrees, such as 360 degrees (at block 318)), the workstation 203 joins or stitches together the received image data to generate a processed image, which may correspond to the interior surface of the element (e.g. the bore) within the nuclear reactor. In some embodiments, the workstation 203 joins or stitches together data from multiple images captured with the camera 112 to generate the processed image data, which may correspond to the interior surface of the bore. In some embodiments, the workstation 203 joins or stitches together the received image data for each position of the camera 112 or the tool 100 (e.g. each rotational position of the camera 112 or the tool 100) to generate the processed image data, such as a panoramic image (at block 320). This process may include using the position information (e.g. axial or rotational information) stored with received image data to join or stitch image data together while accounting for overlapping fields-of-view within received image data. In some embodiments, the workstation 203 generates the processed image, which may correspond to the interior surface of the bore (e.g. the panoramic image) only after image data is received for each position of the camera 112 or the tool 100 (e.g. after a full rotation of the inspection tool 100). However, in other embodiments, the workstation 203 generates and continues to generate or expand the processed image (e.g. the panoramic image) as or after image data is received for each position of the camera 112 or the tool 100, such that the processed image (e.g. the panoramic image) is available for display (and detection, marking, and tracking of defects) at various position of the camera 112 or the tool 100.

[0052] After receiving image data from the camera 112, such as one image captured by the camera 112 or after joining or stitching together the data from multiple images and generating the processed image that may correspond to the interior surface of the bore, the workstation 203 automatically detects one or more defects in the bore based on the processed image (such as the defect 312 represented in the image data 307 illustrated in FIG. 7) at block 322 of FIG. 6. In some embodiments, the workstation 203 is configured to generate the processed image from a plurality of images, each of the plurality of images being of a respective region of the interior surface of the bore, and to detect at least one defect in at least one of the regions. In some embodiments, the workstation 203 is configured to generate the processed image from a plurality of images, each of the plurality of images being of a respective region of the interior surface of the bore, and captured with the camera 112 at a plurality of rotational positions, and to detect at least one defect in at least one of the regions. For example, FIG. 8 illustrates a panoramic image 330 including detected defects 332, 334, and 336. The workstation 203 may detect at least one defect within the processed image. The workstation 203 may detect defects in various ways. As one example, the workstation 203 may compare received image data with image data

representing the interior surface of a bore with no flaws, wherein differences between the image data (added or missing lines or variances in pixel values) are identified as defects.

[0053] As another example, the workstation 203 may apply one or more filters to the image data captured by the camera 112 to detect defects. For example, the workstation 203 may apply a gradient filter to the received image data (in one or more different directions) to generate a binary image and highlight potential defects. A gradient filter determines a magnitude of change between pixel values in a predetermined direction. Accordingly, the binary image generated through application of a gradient filter identifies regions (as dark (black) or light (white) regions) where pixel values changed, which may indicate a defect in the interior surface of bore, which may be composed of a uniform material. In particular, a gradient filter sweeps through an image with a directional sensitive filter (for example, an east-west directional filter) to remove the background and highlight defects (for example, vertically-spanning defects).

[0054] The workstation 203 may store coordinates of detected defects. For example, the workstation 203 may be configured to translate pixels representing a detected defect within the received image data into coordinates within the interior surface of the bore using a predetermined scale between pixel dimensions and bore dimensions. In some embodiments, the workstation 203 also displays the received image data or the processed image, such as the panoramic image, (through the HMI 216) and may mark detected defects in the received image data or the processed image (see, for example, FIG. 8). The workstation 203 may be configured to detect or mark defects that satisfy or exceed one or more configurable thresholds, which may relate to size, depth, location, and the like. For example, the workstation 203 may be configured to only detect defects larger than 0.010 inches (in any dimension). Accordingly, the workstation 203 may be configured to ignore small or insignificant defects.

[0055] In some embodiments, the workstation 203 may be configured to detect defects in received image data using a similar detection process as described above before joining image data from multiple images captured with the camera 112 or before generating the processed image (e.g. the panoramic image). Accordingly, during the inspection method 300, the workstation 203 may provide a user with a real-time or near real-time display of the available inspection results, including any detected defects. Furthermore, in some embodiments, the workstation 203 may be configured to join data from multiple images to generate the processed image that may correspond to the interior surface of the bore as image data is received, as compared to waiting until all image data is received (e.g. as compared to waiting until a full 360 degrees of image data has been received). Again, this processing allows a user to receive inspection results as they are available. [0056] Based on the processed data, which may correspond to the interior surface of the bore (e.g. the panoramic image), or individually received image data, the workstation 203 may also be configured to take one or more measurements, such as the, height, width, or diameter of a tube sheet bore, a circumference of a tube sheet bore, and the like. The workstation 203 may calculate these measurements by counting a number of pixels and multiplying the number of pixels by a conversion factor to determine an actual measurement in engineering units. The workstation 203 may also determine other characteristics of a tube sheet bore, such as surface color, texture, material, and the like. The workstation 203 may save this information (for inclusion in a report as described below), for display within an image, in any desired

combination of information.

[0057] After generating the processed image that may correspond to the interior surface of the bore (e.g. the panoramic image) (at block 320) and detecting any defects from the received image data or the processed image (at block 322), the workstation 203 generates one or more inspection reports (at block 338). The generated inspection report may include the received image data (with any detected defects marked), such as individual image data for one or more positions of the camera 112 or the tool 100, the processed data, which may correspond to the interior surface of the bore, generated by joining data from multiple images captured by the camera 112, or a combination thereof. For example, in some embodiments, the inspection report includes image data associated with each detected defect. In some embodiments, the report also includes additional details about detected defects, such as location (coordinates), size, shape, depth, orientation (vertical or horizontal), angle, class or type, and the like. Any measurements taken of the tube sheet bore may also be included in the inspection report. The inspection report may further provide one or more summaries, such as the number of possible defects detected for each lattice site. The inspection report may also include inspection data, such as a start time, end time, elapsed time, and the like. Also, in some embodiments a coordinate system is added to an image to map out positions (clock positions or angular positions) of the image. This coordinate system may then be used to report defect locations.

[0058] In some embodiments, the report may also include an inspection result, such as "pass" or "fail." For example, depending on the number, size, type, or the like of detected defects, the workstation 203 may be configured to automatically "pass" or "fail" a bore for retubing. This type of automatic categorization reduces or eliminates the need for manual review in some situations. For example, in some embodiments, only "failed" inspections may be subjected to manual review.

[0059] The inspection reports generated by the workstation 203 may be locally stored on the workstation 203 (the storage device 212) and may be output on the HMI 216, such as via a display, a printer, and the like. Alternatively or in addition, the workstation 203 may transmit the inspection reports to an external storage location that may be accessible by one or more devices, such as remote viewing stations providing off-line review and auditing of inspections. The above inspection method 300 can be repeated for each or a subset of tube sheet bores, such an inspection report generated for bores on only one side of a calandria, or in one quadrant or ring of bores of a tube sheet 18. In some embodiments, inspection results from one or more bores (from one or more tube sheets 18) may also be combined into a single report.

[0060] Thus, embodiments described herein provide an automated inspection method that allows for both real-time analysis of nuclear reactor components, such as bores in a tube sheet 18, and off-line analysis using, for example, machine vision software. The automated nature of the inspection allows the inspection to be performed more efficiently (reducing critical path time) and with less errors or inconsistencies.

[0061] As noted above, the inspection processes and/or tools described in the present application are not limited to inspecting tube sheet bores, but may be used to inspect other interior surfaces of a nuclear reactor. For example, a camera may be used to collect images of interior surfaces of the bellows 62, which can be joined or stitched together and processed as described above to detect defects in the bellows 62. Furthermore, in situations where a camera cannot capture image data spanning an entire width of an interior surface, the camera 112 or the inspection tool 100 supporting the camera 112 may be both rotated as described above and axially extended and retracted to collect image data for a plurality of spans of the interior surface, which can be joined or stitched together (e.g., axially stitched together), and processed accordingly.

[0062] For example, for a bellows inspection, a camera can be used to obtain image data at each of a plurality of z-axis axial positions. FIG. 9 illustrates a sample image 400 of the interior surfaces of a bellows taken at one axial position using the camera 112. In situations where the workstation 203 receives multiple images at a particular axial position, the workstation 203 may average the images as described above to generate a single, average image. The workstation 203 "unwraps" the image for each axial position to define at least one region of interest. For example, the workstation 203 may define an outer diameter of a bellows and an inner diameter of a bellows. Each region may be defined by a minimum diameter, a maximum diameter, a start angle, an end angle, and a center point within an image. For example, FIG. 10 illustrates an outer diameter 402 of a bellows 62 defined by a maximum diameter 403 and a minimum diameter 404. After defining one or more regions of interest, the workstation 203 can use a polar function to profile any defined region of interest, and reconstruct any annular region of interest as a flat rectangular strip. For example, FIG. 10 illustrates a flat rectangular strip 406

representing the inner diameter 402 of the bellows 62.

[0063] After the workstation 203 receives image data at each axial position, the workstation can stitch the rectangular strips (taken at different axial positions) together end-to-end to generate a processed image that may be a full representation (e.g. panoramic image) of the bellows 62. For example, FIG. 11 illustrates an example panoramic image 408 of a length of the inner diameter of the bellows 62. The workstation 203 detects defects in the processed image generated by joining data from multiple images captured by the camera 112 as described above, such as by applying one or more gradient filters. FIG. 12 illustrates the panoramic image 408 before (410) and after (412) a gradient filter (an east-west filter) is applied. As illustrated in FIG. 12, the white regions in the filtered image may represent possible defects. The workstation 203 may also calculate various measurements of the bellows, such as a flange area and an overall length (see FIG. 13). All of this information may be included in an inspection report as described above. For example, FIG. 14 illustrates a panoramic image 420 of a bellows 62 overlaid with a coordinate system defined by axial and clock (radial) positions of the panoramic image.

[0064] It should also be noted that the embodiments described above and illustrated in the accompanying figures are presented by way of example only, and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.

Claims

CLAIMS What is claimed is:

1. A system for inspecting an interior surface of an element within a nuclear reactor, the system comprising: an inspection tool including a camera for capturing image data of the interior surface of the element; a tool control system communicating with the inspection tool and for positioning the camera; and a workstation, the workstation configured to: receive image data captured with the camera, detect at least one defect within the image data, and generate and output an inspection report, the inspection report including the received image data and data regarding the at least one defect.

2. The system of claim 1, wherein the workstation is configured to join data from multiple images captured with the camera to generate a processed image and to detect at least one defect within the processed image.

3. The system of claim 1, wherein the tool control system controls a rotational position of the camera relative to an axis of the element.

4. The system of claim 1, wherein the tool control system controls an axial position of the camera relative to the element.

5. The system of claim 2, wherein the workstation is configured to generate the processed image from a plurality of images, each of a respective region of the interior surface of the element, and to detect at least one defect in at least one of the regions.

6. The system of claim 5, wherein the workstation is configured to generate the processed image from a plurality of images, each of a respective region of the interior surface of the element, and captured with the camera at a plurality of rotational positions, and to detect at least one defect in at least one of the regions.

7. The system of claim 1, wherein the data regarding the at least one defect includes a position of the at least one defect along the interior surface.

8. The system of claim 1, wherein the data regarding the at least one defect includes a size of the at least one defect based on a scale between a dimension of pixels included in the image data and dimensions of the interior surface.

9. The system of claim 1, wherein the workstation is further configured to mark the at least one defect within the received image data.

10. The system of claim 1, wherein the workstation is further configured to mark the at least one defect within the received image data when a size of the at least one defect exceeds a configurable size threshold.

11. The system of claim 1, wherein the workstation is further configured to categorize inspection of the element based on the at least one defect.

12. The system of claim 1, wherein the element is a bore of a tube sheet.

13. The system of claim 1, wherein the workstation is further configured to process received image data captured by the camera to determine whether to reject the received image data.

14. The system of claim 13, wherein the workstation is further configured to instruct the camera to capture additional image data when the workstation rejects the received image data.

15. The system of claim 13, wherein the workstation is further configured to instruct the tool control system to rotate the camera to a subsequent rotational position when the workstation does not reject the received image data.

16. The system of claim 1, wherein the workstation is further configured to determine a rotational position of the camera and associate the rotational position with image data captured while the camera is positioned at the rotational position.

17. The system of claim 3, wherein the workstation is configured to determine the rotational position of the camera based on signals from an encoder sensing a physical position of a radial motor associated with the camera.

18. The system of claim 6, wherein the workstation is configured to average images captured by the camera for one of the plurality of rotational positions when the camera captures more than one image for the one of the plurality of rotational positions.

19. The system of claim 6, wherein the workstation is further configured to process the image data captured by the camera at the plurality of rotational positions of the camera to detect the at least one defect.

20. The system of claim 1, wherein the workstation is configured to detect the at least one defect in the received image data by applying a gradient filter to the image data.

21. The system of claim 6, wherein the workstation is further configured to output image data for at least one of the plurality of rotational positions of the inspection tool on a display in real-time.

22. The system of claim 21, wherein the workstation is further configured to mark detected defects within the image data output on the display.

23. The system of claim 3, wherein the workstation is configured to detect movement of features across the received image data as the camera rotates.

24. A method of inspecting an interior surface of an element within a nuclear reactor, the method comprising: capturing image data of the interior surface of the element using a camera of an inspection tool inserted within the element; detecting at least one defect within the captured image data; marking the at least one defect within the captured image data; and outputting the captured image data with the marked at least one defect.

25. The method of claim 24, comprising joining data from multiple images captured with the camera to generate a processed image of the interior surface of the element within the nuclear reactor and detecting at least one defect in the processed image.

26. The method of claim 24, comprising rotating the camera about a longitudinal axis of the element to a desired rotational position.

27. The method of claim 24, comprising moving the camera along a longitudinal axis of the element to a desired axial position of the camera.

28. The method of claim 24, comprising generating the processed image from a plurality of images, each of a respective region of the interior surface of the element, and detecting at least one defect in at least one of the regions.

29. The method of claim 28, comprising generating the processed image from a plurality of images, each of a respective region of the interior surface of the element and captured with the camera at a plurality of rotational positions, and detecting at least one defect in at least one of the regions.

30. The method of claim 24, comprising capturing image data of the interior surface of the element with the camera at a plurality of positions.

31. The method of claim 24, comprising capturing image data of the interior surface of the element with the camera at a plurality of rotational positions.

32. The method of claim 31, comprising: capturing image data of the interior surface of the element with the camera at a first rotational position; rotating the camera to a second rotational position; and capturing image data of the interior surface of the element with the camera at the second rotational position.

33. The method of claim 31, comprising rotating the camera by a predetermined degree to capture image data at each rotational position of the plurality of rotational positions.

34. The method of claim 24, comprising applying a gradient filter to at least a portion of the captured image data to detect the at least one defect within the captured image data.