CA2986983A1 - System and method for nuclear reactor inspection - Google Patents

Abstract

A system for nuclear reactor inspection including: a bracelet contact portion for urging an inspection bracelet along a feeder tube without contacting the feeder tube;
and a mounting portion for supporting the bracelet contact portion, the mounting portion including apparatus for mounting the system to end fittings of the nuclear reactor. In some cases, the bracelet contact portion may include: an arm configured to pitch, yaw, roll and move axially along a longitudinal axis of the arm; a fork portion attached to the arm configured to pitch and yaw; a ring portion attached to the fork portion such that the fork portion controls an orientation of the ring portion, wherein the arm and fork portion interact to move the ring portion along the feeder tube around bends having various radii. In some cases, the system may be remotely controlled by providing a master/duplicate system in communication with the remote system.

Description

SYSTEM AND METHOD FOR NUCLEAR REACTOR INSPECTION
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent Application No.
62/427,414 filed November 29, 2016 which is hereby incorporated herein by reference.
FIELD

[0002] The present disclosure relates generally to inspection of components of nuclear reactors. More particularly, the present disclosure relates to a system and method for inspection of feeder tubes in nuclear reactors.
BACKGROUND

[0003] Some pressurized heavy water nuclear reactors, such as the CANDUTM
reactor, require feeder tube inspections to inspect for wall thinning which may arise due to flow assisted corrosion. These feeder tube inspections involve a circular device (sometimes called a "bracelet") having ultrasonic transducers to be manually manipulated over the profile of a feeder tube to perform the inspection. While parts of the feeder tube are straight, feeder tubes also typically include some tighter radius bends which require special, or extra, attention during the inspection and make it difficult for the bracelet to be moved along the feeder tube.

[0004] Currently, in order to inspect the feeder tube, a bracelet is installed around the feeder tube and manually manipulated by an operator located directly in front of the feeder tube being inspected. In most cases, the operator stands on a platform to manipulate the bracelet. However, these inspections are therefore limited based on the accessibility of the feeder tube to the operator and/or the reach of the operator's arm. As these inspections are generally performed on or near the reactor's outage critical path, the proximity of the operator also leaves him/her subject to dose rates. These inspections also require a significant number of operators as there are a large number of feeder tubes.

[0005] As such, there is a need for an improved system and method for inspection of components of nuclear reactors, including feeder tubes.

SUMMARY

[0006] According to an aspect herein, there is provided a system for nuclear reactor inspection including: a bracelet contact portion for urging an inspection bracelet along a feeder tube of a nuclear reactor without contacting the feeder tube; and a mounting portion for supporting the bracelet contact portion, the mounting portion including apparatus for mounting the system to end fittings of the nuclear reactor.

[0007] In some cases, the bracelet contact portion may include: an arm configured to pitch, yaw, roll and provide axial motion along a longitudinal axis of the arm; a fork portion attached to the arm configured to pitch and yaw; a ring portion attached to the fork portion such that the fork portion can control an orientation of the ring portion, wherein the arm and fork portion interact to allow the ring portion to move along the feeder tube around bends having various radii.

[0008] In some cases, the mounting portion may include: a mounting plate, which supports the bracelet contact portion; two or more clamps, which removably connect with the end fittings; and two or more posts, which connect the mounting plate to the clamps, wherein, the mounting plate, clamps and posts are configured such that the mounting portion can move to traverse a face of the nuclear reactor to enable inspection of various feeder tubes.

[0009] Generally speaking, the system may further include the inspection bracelet itself.

[0010] According to another aspect herein, there is provided a system for nuclear reactor inspection including: a master control system including: a master delivery tool system; and a master control processing unit; and a slave delivery tool system, wherein the master control system is in communication with the slave delivery tool system to allow the slave delivery tool system to be controlled remotely to move or urge an inspection bracelet along a feeder tube of the nuclear reactor.

[0011] In some cases, the master delivery tool system may include: a master bracelet contact portion; and a master mounting portion for supporting the master bracelet contact portion, and the slave delivery tool system may include: a slave bracelet contact portion for urging an inspection bracelet along a feeder tube of a nuclear reactor without contacting the feeder tube; and a slave mounting portion for supporting the slave bracelet contact portion, the slave mounting portion including apparatus for mounting the system to end fittings of the nuclear reactor, wherein the slave bracelet contact portion is controlled by movement of the master bracelet control portion via the master control processing unit.

[0012] In these cases, the slave mounting portion may include: a slave mounting plate, which supports the slave bracelet contact portion; two or more clamps, which removably connect with the end fittings; and two or more posts, which connect the mounting plate to the clamps, wherein, the slave mounting plate, clamps and posts are configured such that the slave mounting portion can move to traverse a face of the nuclear reactor to enable inspection of various feeder tubes. In this way, the system can move to another feeder tube after the current feeder tube has been inspected.

[0013] Similar to the above, in this aspect the system may further include the inspection bracelet that is moved along a feeder tube by the slave bracelet contact portion. In particular, the inspection bracelet may encircle between 270 and 360 degrees of a surface of the feeder tube.

[0014] In some cases, the master bracelet contact portion may include: a master fork portion; and a master arm portion, the fork portion located at one end of the master arm portion, the master arm portion in a movable connection with the master mounting portion. In these cases, the master fork portion may be configured to pitch and yaw and the master arm portion may be configured to pitch, yaw, roll and provide axial motion.

[0015] Other aspects and features of the present disclosure will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Embodiments of the present disclosure will now be described, by way of example only, with reference to the attached Figures:

[0017] Figure 1A is a perspective view of a typical nuclear reactor end fitting arrangement;

[0018] Figure 1B is another perspective view of the nuclear reactor arrangement including a bank of feeders;

[0019] Figure 2A perspective view of a nuclear reactor inspection apparatus mounted to the feeding arrangement;

[0020] Figure 2B is a close-up view of the apparatus of Figure 2A;

[0021] Figure 2C is a schematic view of another apparatus for nuclear reactor inspection;

[0022] Figure 3 is a set of perspective views of the nuclear reactor inspection apparatus traversing a feeder tube;

[0023] Figure 4 is a set of views of axes of motion of a fork portion of the nuclear reactor inspection apparatus;

[0024] Figure 5 is a set of views of axes of motion of an arm portion of the nuclear reactor inspection apparatus;

[0025] Figure 6 is a set of views an alternative embodiment of a fork portion of the nuclear inspection apparatus;

[0026] Figure 7 is a perspective view of the nuclear reactor inspection apparatus in a stowed position;

[0027] Figure 8 is a set of views of a mounting portion of the nuclear inspection apparatus traversing end fittings;

[0028] Figure 9 is a schematic view of a portion of the nuclear reactor inspection apparatus and an ultrasonic bracelet; and

[0029] Figure 10 is another schematic view of the nuclear reactor inspection apparatus and an ultrasonic bracelet.
DETAILED DESCRIPTION

[0030] Generally, the present disclosure provides a system and method for inspection of nuclear reactor components. For example, inspection of feeders or feeder tubes within the reactor can be performed to monitor the characteristics of the feeder tubes.
In at least one embodiment, the inspection can be performed to monitor wall thinning within the feeders due to corrosion.

[0031] Typical pressurized heavy water nuclear reactors, such as the CANDUTM
reactor, include various feeder tubes (sometimes referred to as feeders) which may be used to carry and deliver coolant that is required to cool the nuclear fuel and/or extract energy for electricity production. The feeder tubes may also be used to deliver boiled water to turn a turbine. Over time, the insides, or inner walls, of these tubes may thin due to, for example, flow assisted corrosion. For this reason, these tubes are regularly inspected to monitor the feeder tube walls. Embodiments of the system and method disclosed herein improve and facilitate this inspection.

[0032] Turning to Figure 1A, a perspective view of reactor tubes 50 within a nuclear reactor is shown. The reactor tubes 50 are aligned in rows with respect to each other and each reactor tube 50 includes an end fitting 100. Each of the end fittings 100 include a reactor face 104 and are also aligned in rows with respect to each other. Each of the end fittings 100 further includes a feeder port 106 to which a feeder tube (not shown in Fig.
1A) is typically coupled. A set of positioning assembly studs 108 are also located between the reactor tubes 50 for receiving position assembly yokes 110 which keep the end fittings 100 (and thereby, the reactor tubes 50) in place with respect to each other.

[0033] Turning to Figure 1B, a perspective view of a nuclear reactor feeder arrangement 55 is shown. In Fig. 1B, the feeder tubes 112 are shown attached to the feeder ports 106.
Each of the feeder tubes 112 extend from their associated feeder ports 106 of the end fittings 100 and will typically include at least one radius bend 114 and, more typically a set of two or more radius bends 114. Depending on the position of each feeder tube 112 within the nuclear reactor feeder arrangement 55, the radius bends 114 may have various radii of curvature. For example, some radius bends 114 may be described as a small/tight radius bend 114a while other radius bends may be described as a large radius bend 114b. As the radius bends 114 are at different angles based on their location within the arrangement 55, various radii may be included. In some embodiments, the feeder tubes 112 are connected to the feeder port 106 of the end fitting 100 by a flange 116 or the like. The feeder tubes 112 are also typically coupled, for example, welded, to a feeder hub (not shown) at an end opposite to the connection to the feeder port 106. The feeder tubes 112 further include a trapped feeder portion 118.

[0034] Figure 2A shows a perspective view of a system 200 for inspection of a nuclear reactor component, in this case, a feeder tube. The system 200, which may also be referred to as an inspection delivery tool 200, includes a delivery tool (or bracelet control section) 202 and a spider section (or mounting section) 204. The bracelet control section 202 includes a fork portion 206 and an arm portion 208. The mounting section 204 includes a mounting plate 210 which is attached to adjacent reactor faces 104 of adjacent end fittings 100, for example via cup-shaped clamps 212 which are configured to mate with the reactor faces 104. The end fittings 100 can also serve to provide support to the mounting plate 210. In some embodiments, the inspection delivery tool 200 may include more than two clamps 212.
Alternatively, the mounting plate may be attached to the end fittings 100 in another manner that functions in a similar way as cup-shaped clamps 212, for example, by clamps that fit around the circumference of the reactor tubes 50 at the end fitting 100.

[0035] The mounting plate 210 includes a holder 214 for receiving the arm portion 208 of the bracelet control section 202. As will be described in more detail below, the mounting plate 210 may also be configured to move in relation to the end fittings 100 along posts 216, which engage with the mounting plate 210.

[0036] The fork portion 206 includes a shaped ring 218, which is C-shaped in the current embodiment, which assists the inspection process by "pushing" an ultrasonic transducer bracelet 207 (shown in Fig. 9) that is affixed around the feeder tube 112. In some embodiments, the bracelet 207 may be initially located near the feeder flange 116 and the system 200 is placed such that the shaped ring 218 is between the flange 116 and the bracelet 207. In this way, the system 200 can be used to move the bracelet along the feeder tube 112 away from the flange 116 in order to conduct the inspection. A
schematic diagram of this arrangement is shown in Figure 9.

[0037] With this arrangement, control of the system 200 may be performed remotely via an operator, such as via a remote control system, as is described further herein.
This configuration reduces or removes any need for an operator to come closer to the feeder tubes to move the ultrasonic transducer bracelet 207 around the radius bends 114. Figure 2B is an enlarged view of the system 200 mounted, or connected, to the reactor.

[0038] In operation, the fork section 206 has the ability to pitch and yaw (schematically shown in Figure 4) while the arm portion 208 has the ability to pitch, yaw, roll and provide axial motion (schematically shown in Figure 5) in order to assist and enable the inspection process. With these axes of motion, the fork portion 206 of the delivery tool may be urged to traverse the profile of each feeder tube (including the more difficult radius bends) to push the ultrasonic transducer bracelet along each feeder tube to perform inspection of that feeder tube. This will be described in more detail below.

[0039] Figure 2C shows a schematic diagram of another embodiment of a system for nuclear reactor inspection. In this embodiment, the system 230 includes the delivery tool system 200 described above which may be seen as a "slave" delivery system and also includes a "master" delivery tool control system 232. The master control system includes a master control processing unit 233 and a second delivery tool 234. The second delivery tool 234 includes a master fork portion 236 and a master arm portion 238. The master control system 232 further includes a set of electronics for transmitting signals to the slave delivery tool system 230. Communication between the master and slave systems may be wired or wireless and use any of various communication protocols as will be understood by one skilled in the art. In some embodiments, the master control system 232 may be located remote from the slave delivery tool 200 and may contain instrumentation, such as Linear Variable Transducers, encoders, or the like that allow movement of the master control system 232 to be communicated and executed by the slave delivery tool system 230. The master control system 232 may also include a display 240 which is connected with cameras 242 (located proximate the reactor or on the fork portion of the slave delivery tool) to assist in the inspection process.

[0040] In some embodiments, the cameras 242 may be mounted to the slave delivery tool system 230. In another embodiment, the master control system 232 is identical to the slave delivery tool system 230 except that instead of containing motors or actuators, the master control system 232 only includes instrumentation on each axis. In operation, the operator may move the fork portion of the master control system 232 along a dummy feeder. As the operator does this, the 6 axes of the master arm portion 238 will move.
Transducers on the master arm portion 238 may detect how much and how fast each axis moves which may then drive the slave arm portion to move the same amount.

[0041] Similarly, within the spider portion (mounting section) 204 of the slave delivery system 200 is a set of servo motors or linear actuators (not shown) to receive the signals transmitted by the master control system and move the slave delivery system 200 in conjunction with the master control system. Use of the servo motors or linear actuators will be understood by one skilled in the art.

[0042] In operation, an operator holds the fork portion 236 of the master control system 232 and moves the master control fork portion 236 by hand. Signals representing this movement are transmitted from the master control system 232 to the servo motors or linear actuators in the slave delivery tool 200. When the operator moves the master control fork portion 236, the tool axes of the slave delivery tool change such that the instrumentation of the master control system 232 drives the slave delivery tool, so that the slave delivery tool 200 mimics the actions of the operator. By having this "remote" control, the operator may have more space to perform the inspection process. In other words, the operator has more space which may enable the operator to traverse more of the profile of the feeder tube compared to many current systems where the manual, and on-site, traversal of the feeder tube for inspection is limited by operator arm length or the presence of other reactor tubes.
The current system can also allow the operator to avoid dose rates that might otherwise be experienced by the operator.

[0043] In some embodiments, the operator may use the cameras 242 mounted on the slave delivery tool to assist in the inspection process. The master control system may include a dummy feeder 244 which may be used as a guide tool for the operator using the master control delivery tool 232. In one embodiment, the dummy feeder 244 is made to nominal feeder tube design dimensions but may be a smaller diameter, such as bent from smaller diameter tubing. While the dummy feeder 244 provides a guide to a tool path, the dummy feeder 244 permits or allows the operator to deviate from the guide to suit the profile of the feeder being inspected based on the images shown on the display 240 from the cameras 242.

[0044] As the operator moves the fork of the master system along the dummy feeder (causing the fork portion 206 of the slave portion 200 to perform a similar, or exact, action along the feeder tube being inspected), the information collected by the tool system relating to the axes of motion of either the master or the slave delivery tool system may be stored and/or used to create a profile for the feeder tube under inspection. This will generally be an approximate profile only, due to the intentional clearance between the slave fork portion and the feeder tube being inspected. However this profile can be used to correlate the inspection data to the approximate position along the feeder tube profile, with no additional instrumentation.

[0045] In some embodiments, the ultrasonic transducer bracelet may be connected to the fork portion 206 of the slave delivery system 200, generally with a large compliance. By having a large compliance, the operator only needs to loosely follow a feeder path to enable the bracelet to traverse the feeder tube under inspection. This approach makes use of human ability to follow the feeder path along the multiple radius bends. This path is an extremely complicated profile for current systems which use an automated crawler.

[0046] In some embodiments, the ultrasonic transducer bracelet is modified to permit the ultrasonic transducer probes to float independent of each other. The strap of the ultrasonic transducer bracelet may also be modified to allow it to be engaged remotely through the delivery tool. This is schematically shown in Figure 10. Depending on the shape and design of the ultrasonic transducer bracelet, multiple passes may be required to fully inspect the feeder tube, however, in some embodiments, the ultrasonic transducer bracelet can cover approximately 270 degrees or a full circumference of the feeder tube circumference such that the inspection may be performed in one or two passes.

[0047] While the embodiments herein do not rely on increased circumferential coverage, the system may include apparatus to remotely rotate the bracelet and perform several passes without needing to manually manipulate the bracelet. In one embodiment, two separate inspection "slave" delivery tools may be used to perform the feeder inspection and the near weld inspection to match existing processes and procedures. A
calibration feeder may be located on the mounting portion to allow for testing of the equipment and processes.

[0048] An advantage of the current embodiments is that since the fork portion 206 of the slave delivery system is pushing the ultrasonic transducer bracelet without needing to contact the surface of the feeder tube being inspected and or relying on contact with the feeder tube for motive power, the slave delivery tool is unaffected by surface condition of the feeder tube, corrosion, feeder ovality, debris, welds, or water on the feeder tube.

[0049] As the operator moves the master control fork portion along a "line"
that approximately follows a natural path or profile of the feeder tube being inspected, causing the slave fork portion to follow along the extrados of a first bend and the intrados of a second bend of the feeder tube, as schematically shown in the series of drawings of Figure 3, the pitch motion of the fork portion 206 delivers some force to move the ultrasonic transducer bracelet around the bends, whereas the yaw motion of the slave fork portion 206 is relatively lower force, as it only accommodates small changes during the feeder path and when rotating the tool to reset a new bracelet orientation. For this reason, in one embodiment, the pitch of the slave fork portion may be actuated by a linkage, and the slave fork portion yaw motion may be delivered via a wire control cable, although a linkage version is also feasible (as schematically shown in Figure 6).

[0050] Another advantage of embodiments herein is that since most or all of the slave delivery tool control motions are performed, or actuated, remotely, the use of motors or hydraulics located within the feeder nest itself (such as automated crawlers or the like) can be reduced or eliminated. This property of the current disclosure may allow the actuators to be sized with significant margins to produce a more robust system. There is an added benefit that the arm portion 208 of the slave system 200 may be used to support and manage ultrasonic transducer bracelet signal cables and couplant line so that they are not hanging randomly.

[0051] In some embodiments, the slave delivery tool is supported by the mounting plate engagement to the end fittings. The spider, or mounting, portion may support junction boxes and cables required for signal, power and water couplant lines with the control cabinet located on the reactor vault floor. The mounting portion may be remotely controlled or may be automated to traverse the entire reactor face (in a "spider"-like fashion) and deliver the slave delivery tool to any feeder tube. The two "cups" are configured to have independent axial motion and the distance between the cups is also controlled by a linear axis which allows the slave delivery tool to "walk" up and down each reactor face (Figure 8), but also permits the tool to accommodate the end fitting positions, with offset between adjacent end fittings. This permits the tool to be delivered in parallel with other work, or during windows of opportunity in parallel with other work. When the slave delivery tool system 200 is moved from one pair of end fittings to another pair of end fittings, to enable inspection of another feeder tube, the fork portion and the arm portion may be in a stowed position such as schematically shown in Figure 7.

[0052] In one embodiment, the tool design lends itself to being phased in, to allow trial use during outages. For example the delivery tool system may be installed by an operator on the reactor face, and the "remote" operator could be located on the same platform or on the vault floor.

[0053] One advantage of embodiments in the current disclosure is that the system may be operated in front of the feeder, or reactor face, or from a remote location.
Another advantage is that the system may be operated in parallel with other reactor face outage operations to reduce outage critical path. A further advantage is potential reduction in an operator's exposure to dose. Further advantages may include a reduction in associated operation and training costs.

[0054] Another advantage of embodiments in the current disclosure is that the system is generally not constrained by the surface finish of the feeder, the profile of the feeder or any corrosion, debris or water that may be located on a surface of the feeder or feeder tube. As another advantage, the system can benefit from human interaction to follow a profile or path of the feeder and improve the reliability and possibly shorten the time to perform the inspection. The system may also provide an extended inspection compared with current inspections because of, for example, the reduced need to be concerned about dose levels.
Finally, the system of the disclosure may be deployed in a phased approach whereby the system could be used during current feeder inspection outages alongside a manually operated inspection.

[0055] In the preceding description, for purposes of explanation, numerous details are set forth in order to provide a thorough understanding of the embodiments.
However, it will be apparent to one skilled in the art that these specific details may not be required. In other instances, well-known structures may be shown in block diagram form in order not to obscure the understanding. For example, specific details are not provided as to whether the embodiments described herein or elements thereof are implemented as a software routine, hardware circuit, firmware, or a combination thereof.

[0056] Embodiments of the disclosure or elements thereof may be represented as a computer program product stored in a machine-readable medium (also referred to as a computer-readable medium, a processor-readable medium, or a computer usable medium having a computer-readable program code embodied therein). The machine-readable medium can be any suitable tangible, non-transitory medium, including magnetic, optical, or electrical storage medium including a diskette, compact disk read only memory (CD-ROM), memory device (volatile or non-volatile), or similar storage mechanism. The machine-readable medium can contain various sets of instructions, code sequences, configuration information, or other data, which, when executed, cause a processor to perform steps in a method according to an embodiment of the disclosure. Those of ordinary skill in the art will appreciate that other instructions and operations necessary to implement the embodiments can also be stored on the machine-readable medium. The instructions stored on the machine-readable medium can be executed by a processor or other suitable processing device, and can interface with circuitry to perform the described tasks.

[0057] The above-described embodiments are intended to be examples only.
Alterations, modifications and variations can be effected to the particular embodiments by those of skill in the art. The scope of the claims should not be limited by the particular embodiments set forth herein, but should be construed in a manner consistent with the specification as a whole.

Claims (11)

WHAT IS CLAIMED IS:

1. A system for nuclear reactor inspection comprising:
a bracelet contact portion for urging an inspection bracelet along a feeder tube of a nuclear reactor without contacting the feeder tube; and a mounting portion for supporting the bracelet contact portion, the mounting portion comprising apparatus for mounting the system to end fittings of the nuclear reactor.

2. A system according to claim 1 wherein the bracelet contact portion comprises:
an arm configured to pitch, yaw, roll and provide axial motion along a longitudinal axis of the arm;
a fork portion attached to the arm configured to pitch and yaw;
a ring portion attached to the fork portion such that the fork portion can control an orientation of the ring portion, wherein the arm and fork portion interact to allow the ring portion to move along the feeder tube around bends having various radii.

3. A system according to claim 2 wherein the mounting portion comprises:
a mounting plate, which supports the bracelet contact portion;
two or more clamps, which removably connect with the end fittings; and two or more posts, which connect the mounting plate to the clamps, wherein, the mounting plate, clamps and posts are configured such that the mounting portion can move to traverse a face of the nuclear reactor to enable inspection of various feeder tubes.

4. A system according to claim 1 wherein the system further includes the inspection bracelet.

5. A system for nuclear reactor inspection comprising:
a master control system comprising:
a master delivery tool system; and a master control processing unit; and a slave delivery tool system, wherein the master control system is in communication with the slave delivery tool system to allow the slave delivery tool system to be controlled remotely.

6. A system according to claim 5 wherein the master delivery tool system comprises:
a master bracelet contact portion; and a master mounting portion for supporting the master bracelet contact portion, and the slave delivery tool system comprises:
a slave bracelet contact portion for urging an inspection bracelet along a feeder tube of a nuclear reactor without contacting the feeder tube; and a slave mounting portion for supporting the slave bracelet contact portion, the slave mounting portion comprising apparatus for mounting the system to end fittings of the nuclear reactor, wherein the slave bracelet contact portion is controlled by movement of the master bracelet control portion via the master control processing unit.

7. A system according to claim 6 wherein the slave mounting portion comprises:
a slave mounting plate, which supports the slave bracelet contact portion;
two or more clamps, which removably connect with the end fittings; and two or more posts, which connect the mounting plate to the clamps, wherein, the slave mounting plate, clamps and posts are configured such that the slave mounting portion can move to traverse a face of the nuclear reactor to enable inspection of various feeder tubes.

8. A system according to claim 5 wherein the system further includes an inspection bracelet.

9. A system according to claim 8 wherein the inspection bracelet encircles between 270 and 360 degrees of a surface of the feeder tube.

10. A system according to claim 6 wherein the master bracelet contact portion comprises:
a master fork portion; and a master arm portion, the fork portion located at one end of the master arm portion, the master arm portion in a movable connection with the master mounting portion.

11. A system according to claim 10 wherein the master fork portion is configured to pitch and yaw and the master arm portion is configured to pitch, yaw, roll and provide axial motion.