Process and tool for expanding a reactor pressure vessel nozzle to mitigate primary coolant leakage
The nozzle expansion tool addresses nozzle leakage by remotely expanding the reactor pressure vessel nozzle using a frame, drive system, and expansion roller device, effectively sealing leaks and stabilizing welds.
Patent Information
- Application Number
- JP2024572275
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-09
- Filing Date
- 2023-06-06
- Publication Date
- 2025-07-08
AI Technical Summary
Cracks and leakage occur in the welds of reactor pressure vessel nozzles due to thermal fluctuations and stress corrosion, necessitating an improved method to seal the nozzle penetration.
A nozzle expansion tool with a frame, drive system, and expansion roller device is used to remotely expand the nozzle within the reactor pressure vessel, utilizing vacuum cups for stabilization and a rotating mandrel for radial expansion.
Effectively seals leaks by expanding the nozzle to relieve stress and stabilize the welds, allowing for remote and underwater operation.
Smart Images
Figure 2025521218000001_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to a process and tool for implementing an expansion of a reactor pressure vessel nozzle to mitigate primary coolant leakage.
Background Art
[0002] In this section, background information related to the present disclosure is provided, which is not necessarily prior art.
[0003] During reactor operation, the inlet nozzles of the reactor pressure vessel are subject to large thermal fluctuations as they discharge steam and hot water from the reactor pressure vessel. Cracks may occur in the welds fixing the nozzles due to rapid temperature changes and stress corrosion cracking in the welds, and in some cases, leakage may occur around the nozzle penetration of a boiling water reactor. Therefore, it is desirable to provide an improved method and apparatus for sealing the nozzle penetration.
Summary of the Invention
Problems to be Solved by the Invention
[0004] This section provides a general overview of the present disclosure and does not disclose the entire scope or all elements of the present disclosure comprehensively.
[0005] The present disclosure relates to a tool and method for roll-expanding a nozzle within a reactor pressure vessel to mitigate leakage around the nozzle. The roll-expansion of the nozzle is an effective and economical solution for sealing the leakage of the nozzles of the reactor pressure vessel of a boiling water reactor, and can be performed remotely from above the pressure vessel and using tools underwater.
Means for Solving the Problems
[0006] According to one embodiment of the present disclosure, the nozzle expansion tool includes a frame and a drive system on the frame. The rotating mandrel is drivably connected to the drive system and engageable with the expansion roller device. A plurality of vacuum cups are attached to the frame and include vacuum joints configured to be connected to a vacuum source respectively.
[0007] According to one embodiment of the present disclosure, the depth adjustment mechanism is connected to the expansion roller device and configured to adjust the distance that the expansion roller device extends from the frame.
[0008] According to yet another example of the present disclosure, a method for repairing a crack in a nozzle within a reactor pressure vessel of a boiling water reactor includes lowering a nozzle expansion tool into the reactor pressure vessel. The expansion roller device of the nozzle expansion tool is aligned with the opening of the nozzle. The vacuum cup is supported by an expansion system and engages with the wall of the reactor pressure vessel. The expansion system is retracted to draw the expansion roller device into the nozzle, the drive motor of the nozzle expansion tool is actuated to engage and rotate the rotating mandrel with the expansion roller device, and the nozzle is expanded.
[0009] Further application fields will become apparent from the description provided herein. The description and examples in this summary are for illustrative purposes only and do not limit the scope of the present disclosure.
Brief Description of the Drawings
[0010]
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[0011] The drawings described herein are for the purpose of illustrating only selected embodiments and are not intended to limit the scope of the present disclosure to all possible embodiments.
[0012] Corresponding reference numerals indicate corresponding parts throughout several views of the drawings.
[0013] Next, exemplary embodiments will be described in more detail with reference to the accompanying drawings.
[0014] The exemplary embodiments are provided to thoroughly disclose the present disclosure and fully convey its scope to those skilled in the art. To fully understand the embodiments of the present disclosure, a plurality of specific details are described, such as examples of specific components, devices, and methods. It will be apparent to those skilled in the art that it is not necessary to adopt the specific details, that the exemplary embodiments can be embodied in multiple different forms, and that none of them should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
[0015] The terms used herein are for the purpose of describing particular exemplary embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an", and "the" may be intended to include the plural as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "including", and "having" are inclusive and thus specify the presence of the recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Method steps, processes, and acts described herein need not necessarily be performed in the particular order discussed or illustrated, unless specifically specified as the order of performance. It will also be understood that additional or alternative steps may be employed.
[0016] When an element or layer is described as "resting on", "engaging with", "connected to", or "coupled to" another element or layer, it may be in direct contact, engagement, connection, or coupling with the other element or layer, or there may be intervening elements or layers. In contrast, when an element is described as "directly resting on", "directly engaging with", "directly connected to", or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other terms used to describe the relationship between elements should be interpreted similarly (e.g., "between" and "directly between", "adjacent" and "directly adjacent", etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.
[0017] In this specification, terms such as first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another. As used herein, the terms "first", "second", and other numerical terms do not necessarily imply an order or sequence unless clearly indicated by the context. Thus, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or section described hereinafter may be referred to as the second element, component, region, layer, or section.
[0018] In this specification, spatially relative terms such as "inner", "outer", "directly below", "below", "downward", "up", "upward", etc. may be used to describe the relationship between one or more elements or features and one or more other elements or features as shown in the figures for ease of explanation. Spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figure is turned over, an element described as "below" or "directly below" another element or feature will be oriented "above" the other element or feature. Thus, the exemplary term "below" can encompass both upward and downward orientations. The device may be in other orientations (such as a 90-degree rotated orientation or other orientations), and the spatially relative descriptors used in this specification will be interpreted accordingly.
[0019] Referring to FIG. 1, a nozzle expansion tool 10 inserted into the opening of a nozzle N of a reactor pressure vessel RPV in accordance with the principles of the present disclosure is shown. Referring to FIGS. 1 to 3, the nozzle expansion tool 10 includes a frame 12 that supports a drive motor 14, a planetary gear device 16, and an expansion roller device 18. The drive motor 14 includes directional fluid inlets 14a, 14b (clockwise and counterclockwise directions) and a fluid exhaust port 14c for driving the drive motor 14 in either the clockwise or counterclockwise direction. The drive motor 14 can be driven pneumatically or hydraulically and includes a drive shaft 20 connected to the planetary gear device 16 to drive an output coupling 22 that drives a rotary mandrel 24 of the expansion roller device 18. The output coupling 22 includes an internal spline that is connected to external splines on a gear device output shaft 16a and on the mandrel 24. The drive motor 14 may optionally include a separate planetary gear device 14d.
[0020] Referring to FIG. 8, the linear actuator 26 is operable to move the drive motor 14, the planetary gear device 16, the output coupling 22, and the rotary mandrel 24 in the front - rear direction with respect to the frame 12, as will be described in more detail herein. The expansion roller device 18 includes an elongate sleeve 28 having an expansion head 30 that supports a plurality of expansion rollers 32. This type of expansion roller device 18 is generally well - known in the art. The rotary mandrel 24 includes a tapered outer surface 34 that engages the expansion rollers 32 and, when driven in a first expansion direction, presses the expansion rollers 32 outward. When the rotary mandrel 24 rotates, the expansion rollers 32 are drawn further inward (to the right as viewed in FIG. 8) between the expansion rollers 32. The expansion roller device 18 rotates with the rotary mandrel 24 to continuously expand the expansion rollers 32 radially outward, causing the expansion of the nozzle N for the purpose of relieving leakage. When the rotary mandrel 24 is rotated in the opposite direction, the rotary mandrel 24 tends to be pulled away from the expansion rollers 32 (in the left - hand direction as viewed in FIG. 8) such that the expansion rollers 32 are spaced radially inward from contact with the wall of the nozzle N.
[0021] Referring to FIG. 1, the frame 12 includes a top frame member 36, a front frame member 38, and at least one side frame member 40 (best shown in FIG. 5). The top frame member 36 supports a pair of decorative modules 42 each including a hook to which a suspension cable 44 engages.
[0022] The front frame member 38 supports a plurality of vacuum cups 46 each including a vacuum joint 48. In the illustrated embodiment, four vacuum cups 46 are provided, although the number of vacuum cups 46 may be more or less. A plurality of bumper stoppers 49 are provided adjacent to a corresponding one of the vacuum cups 46 to limit the amount of depression of the vacuum cups 46.
[0023] An additional vacuum cup 50 is provided at the end of the tool locator mechanism 52. The vacuum cup 50 is supported by a pair of guide rods 54 slidably received in a guide block 56. As shown in FIG. 1, the tool locator mechanism 52 includes a drive cylinder 58 and a drive piston 60 operable to extend and retract the vacuum cup 50 and the guide rods 54 away from or toward the front frame member 38. The front frame member 38 includes an opening 62 through which the guide rod 54 and the piston 60 extend.
[0024] The tool locator mechanism 52 can be extended forward to engage the vacuum cup 50 with the side wall of the reactor pressure vessel PRV. A vacuum pressure is applied to the joint of the vacuum cup 50, and then the drive piston 60 is pulled inward to draw the tool 10 toward the wall of the reactor pressure vessel PRV until the vacuum cup 46 engages the wall, and the expansion roller device 18 is drawn into the opening of the nozzle N. The vacuum cup 46 is applied with a vacuum pressure through the joint to fix and stabilize the tool 10 against the wall surface when operating the expansion roller device 18 to expand the nozzle N.
[0025] The frame 12 further includes a drive system support structure 64 that supports the hydraulic motor 14, the planetary gear device 16, the output coupling 22, and the rotary mandrel 24 with respect to the upper frame member 36, the side frame member 40, and the front frame member 38. As shown in FIG. 8, the drive system support structure 64 is moved back and forth by a linear actuator 26 (in the form of an air cylinder drive). The guide block 56 can also be supported by the top frame member 36 directly or via an intermediate frame member 66. A cross brace member 68 can be provided between the side frame member 40 and the front frame member 38. It should be understood that additional frame members and support structures can be provided as needed to support the various components of the nozzle expansion tool 10.
[0026] Referring to FIG. 9, the telescopic reaction pole 70 can be connected to the side frame member 40 and used to guide the nozzle extension tool 10 from above the reactor pressure vessel RPV to a predetermined position. As shown in FIGS. 4 and 8, the side frame member 40 can include a pair of attachment members 72 for receiving the reaction pole 70. The reaction pole 70 is used to cancel the rotational force applied to the nozzle extension tool 10 during the nozzle extension operation. The nozzle extension tool 10 can be suspended by a hoist (not shown) connected to the cable 44.
[0027] Referring to FIG. 8, the mandrel support housing 74 is received in the opening 76 of the front frame member 38 and rotatably supports the elongated sleeve 28 of the expansion roller device 18 via the bearing portion 78. A threaded shaft collar 80 can be received on the threaded end portion of the elongated sleeve 28 that supports the bearing portion 78, together with the raised shoulder 82 of the elongated sleeve 28. The mandrel support housing 74 is supported by a transport portion 84 that can be axially moved in the front-rear direction by a depth adjustment mechanism 86.
[0028] As best shown in FIGS. 5 through 7, the depth adjustment mechanism 86 includes a pair of connection portions each including a first link arm 88 that is fixed to the side frame member 40 by a pivot pin 90 at the first end and connected to a threaded adjustment rod 92 via an adjustment pin 94 at the second end. The second link arm 96 includes a first end connected to the adjustment pin 94 and a second end connected to a drive pin 98 connected to the transport portion 84. The depth adjustment mechanism 86 can be adjusted by rotating the threaded adjustment rod 92 clockwise or counterclockwise. The tool engagement adapter 100 is attached to the threaded adjustment rod 92 and can be engaged by a rotary tool to adjust the depth adjustment mechanism 86 by moving the adjustment pins 94 of the upper and lower connection portions closer to or farther from each other.
[0029] In FIG. 5, the depth adjustment mechanism 86 is shown with the expansion roller device 18 in the most forward position relative to the front frame member 38. In FIG. 6, the depth adjustment mechanism 86 is shown with the expansion roller device 18 in an intermediate position relative to the front frame member 38. In FIG. 7, the depth adjustment mechanism 86 is shown with the expansion roller device 18 in the most rearward position relative to the front frame member 38. During the nozzle expansion operation, the nozzle expansion tool 10 can be operated by arranging the expansion roller device 18 at each of different positions.
[0030] During operation, the hoisting machine connected to the suspension cable 44 and the reaction pole 70 is used to lower and guide the nozzle expansion tool 10 into the reactor pressure vessel RPV, operate the vacuum cup 50, and guide and draw the expansion head 30 into the opening of the nozzle N on the side wall of the reactor pressure vessel RPV. Once the expansion head 30 is completely inserted into the nozzle N, suction can be applied to the vacuum cup 46 via the vacuum joint 48 to fix and stabilize the nozzle expansion tool 10 to the side wall of the reactor pressure vessel RPV. The pair of bubble levels 106, 108 can be attached to the frame 12 to assist in visually aligning the nozzle expansion tool 10 horizontally and orienting it at a predetermined position. In addition, as illustrated in FIG. 2, the tool locator mechanism 52 can be utilized by expanding the tool locator mechanism 52 to the expanded position, engaging the vacuum cup 50 with the wall, retracting the tool locator mechanism 52, pulling the nozzle expansion tool 10 toward the wall, and inserting the expansion head 30 into the nozzle N.
[0031] Once the expansion head 30 is inserted into the nozzle N at the desired depth by adjustment of the depth adjustment mechanism 86, the support structure 64 can be advanced and the nozzle expansion tool 10 can be actuated by bringing the rotary mandrel 24 into contact with the expansion roller 32. Subsequently, the motor 14 is actuated by supplying pneumatic or hydraulic fluid to the rotary motor 14 to rotate the expansion head 30, generating a radial force on the roller 32 while rotating within the nozzle N. The rotational movement of the expansion head 30 causes the expansion of the wall of the nozzle N at the desired position to repair or relieve the leakage therein.
[0032] The nozzle expansion tool 10 can be remotely deployed within the reactor pressure vessel RPV and can also be used for underwater operations. The expansion rolling process is intended to be carried out until a predetermined torque value is obtained, which is designed to repair leaks caused by cracks in the nozzle attachment welds, according to the test. The predetermined torque value can be determined based on the torque calibration fixtures used before and after the use of the tool so that a consistent roll forming torque is reliably applied. The vacuum cups 46, 50 are utilized to stabilize the nozzle expansion tool 10 during the expansion process.
[0033] Referring to FIGS. 10 and 11, a calibration device 120 connected to the output coupling portion 22 of the nozzle expansion tool 10 is shown. As shown in FIG. 11, the calibration device 120 is fixed to the front frame member 38 by an engagement pin 122. When pneumatic or hydraulic fluid pressure is applied to the drive motor 14, the fluid pressure can be associated with the torque level measured by the strain gauge of the calibration device 120 in order to determine the pressure (psi) versus torque (foot-pound) characteristic curve of the nozzle expansion tool 10. Thus, the nozzle expansion tool 10 can be calibrated before and after tool operation to apply a desired torque to the rotating mandrel 24 by applying the pressure associated with the operation of the nozzle expansion tool 10 to the drive motor 14. The calibration of the nozzle expansion tool 10 can also be used to detect damage to the nozzle expansion tool 10. The calibration device 120 can include a monitor system 124 for monitoring the torque level along with the fluid pressure level.
[0034] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in the selected embodiment, even if not specifically shown or described. They can also be varied in various ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Claims
1. A frame, a drive system on the frame, a rotary mandrel drivingly connected to the drive system, an expansion roller device engageable with the rotary mandrel, a plurality of vacuum cups attached to the frame, each including a vacuum joint configured to be connected to a vacuum source, A nozzle expansion tool comprising:
2. The nozzle expansion tool according to claim 1, further comprising at least one bumper stop extending from the front surface of the frame.
3. The nozzle expansion tool according to claim 1, further comprising an additional vacuum cup supported by a telescopic extension system with respect to the front end of the frame.
4. The nozzle expansion tool according to claim 1, further comprising a depth adjustment mechanism connected to the expansion roller device and configured to adjust the distance by which the expansion roller device extends from the frame.
5. The nozzle expansion tool according to claim 4, wherein the depth adjustment mechanism includes a mandrel support housing that rotatably supports the mandrel and is axially movable with respect to the frame.
6. The nozzle expansion tool according to claim 5, wherein the depth adjustment mechanism includes a linkage system adjustable by a threaded rod to expand and contract the position of the mandrel support housing with respect to the frame.
7. The nozzle expansion tool according to claim 1, wherein the drive system includes one of a pneumatic motor and a hydraulic motor.
8. The nozzle expansion tool according to claim 1, wherein the drive system is supported by a support structure movable in the front-rear direction with respect to the frame.
9. A frame, a drive system on the frame, a rotary mandrel drivingly connected to the drive system, an expansion roller device extending from the frame and engageable with the rotary mandrel, a depth adjustment mechanism connected to the expansion roller device and configured to adjust the distance by which the expansion roller device extends from the frame, A nozzle expansion tool comprising:
10. A plurality of vacuum cups attached to the frame, each including a vacuum joint configured to be connected to a vacuum source, and an additional vacuum cup supported by an expansion system telescopic with respect to the front end of the frame, The nozzle expansion tool according to claim 9, further comprising:
11. The depth adjustment mechanism includes a mandrel support housing that rotatably supports the mandrel and is axially movable relative to the frame, the nozzle expansion tool according to claim 9.
12. The depth adjustment mechanism includes a link system adjustable by a threaded rod to expand and contract the position of the mandrel support housing relative to the frame, the nozzle expansion tool according to claim 11.
13. The drive system includes one of a pneumatic motor and a hydraulic motor, the nozzle expansion tool according to claim 9.
14. The drive system is supported by a support structure movable in the front-rear direction relative to the frame, the nozzle expansion tool according to claim 9.
15. The nozzle expansion tool according to claim 9 further includes a reaction pole connected to the frame.
16. A method of repairing a leak in a nozzle of a reactor pressure vessel of a boiling water reactor, comprising: suspending a nozzle expansion tool into the reactor pressure vessel; aligning an expansion roller device with an opening of the nozzle; engaging a wall portion of the reactor pressure vessel with a vacuum cup supported by an expansion system; retracting the expansion system to draw the expansion roller device into the nozzle; operating a drive motor of the nozzle expansion tool to engage and rotate a rotating mandrel with the expansion roller device to expand the nozzle.
17. The suspending step according to claim 16 includes connecting a reaction pole to the nozzle expansion tool and lowering the nozzle expansion tool into the reactor pressure vessel via a suspension cable.
18. supporting a plurality of vacuum cups attached to a frame of the nozzle expansion tool against the wall portion of the boiling water reactor; applying a vacuum to the plurality of vacuum cups to fix the frame to the wall portion of the reactor pressure vessel; The method according to claim 16 further comprising.
19. After the step of operating the drive motor of the nozzle expansion tool to engage and rotate the rotating mandrel with the expansion roller device to expand the nozzle, The method according to claim 16, further comprising adjusting the position of the nozzle expansion tool relative to the frame so that the expansion roller device is disposed at different positions within the nozzle, and again actuating the drive motor of the nozzle expansion tool to engage and rotate the rotary mandrel with the expansion roller device to expand the nozzle at different positions.
20. The method according to claim 16, further comprising calibrating the nozzle expansion tool to determine the relationship between the pressure supplied to the drive motor and the torque applied to the rotary mandrel.